On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
>
> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.

You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.

Here is an authoritative overview:
https://theconversation.com/can-my-electric-car-power-my-house-not-yet-for-most-drivers-but-vehicle-to-home-charging-is-coming-163332

News of a work in progress to make home backup routine with no special equipment required:
https://www.atlasevhub.com/weekly_digest/here-if-you-need-evs-as-backup-batteries/

The cost for equipment to do that is top dollar because they sell so few. There's no logical connection between present cost and a hypothetical mass produced product.

On Thursday, November 17, 2022 at 8:17:58 AM UTC-5, Commander Kinsey wrote:
> On Thu, 17 Nov 2022 13:03:57 -0000, Fred Bloggs <bloggs.fred...@gmail.com> wrote:
>
> > On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> >>
> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> >
> > You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> >
> > Here is an authoritative overview:
> > https://theconversation.com/can-my-electric-car-power-my-house-not-yet-for-most-drivers-but-vehicle-to-home-charging-is-coming-163332
> >
> > News of a work in progress to make home backup routine with no special equipment required:
> > https://www.atlasevhub.com/weekly_digest/here-if-you-need-evs-as-backup-batteries/
> >
> > The cost for equipment to do that is top dollar because they sell so few. There's no logical connection between present cost and a hypothetical mass produced product.
> Rewrite all that considering I know the difference between power and energy, I have a fucking physics degree. When I said 80kW I meant 80kW, not 80kWh. Do you seriously think a car motor only draws 10kW?

Your so-called degree was a woefully inadequate preparation for dealing with reality if you have to ask such a stupid question.

>
> And that last link doesn't tell you how to do it, just sales waffle about Ford are getting to it.

It wasn't a DIY project article. The responsible authorities don't want clueless yokels touching anything to do with it, so much so you may juts be liable to arrest if you do.

>
> Pretty easy really, you find the 400V battery wire and connect a convertor to it to make 240VAC.

There are many more considerations to doing that you're unaware of.

On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
>> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
>>
>> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
>
>You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
>

He clearly said that the battery can deliver 80 KW of power. No 80 KWH
car is going to be limited to 10 KW into the motors. Ecars are all
about acceleration.

You need to learn how to read and how to discuss.

On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
>
> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> >>
> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> >
> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> >
> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> car is going to be limited to 10 KW into the motors. Ecars are all
> about acceleration.

That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.

I'll go out on a limb and say nearly all the battery energy goes to breaking air resistance at constant speed. There's no getting around the basic requirement of having to supply torque at speed to the drive shaft to overcome the square law wind resistance. With the exception of some arrested development types, most of the relatively affluent owners should be past the thrill driving stage of their lives.

>
> You need to learn how to read and how to discuss.

On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
>> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>>
>> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
>> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
>> >>
>> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
>> >
>> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
>> >
>> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
>> car is going to be limited to 10 KW into the motors. Ecars are all
>> about acceleration.
>
>That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.

The misunderstanding was yours. The nastiness too.

The question made sense. Why a 10 KW inverter? The answer is probably,
it's enough for a house backup and a bigger inverter would cost more.

Battery cooling could be involved too, for a parked car.

On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
>
> >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> >> <bloggs.fred...@gmail.com> wrote:
> >>
> >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> >> >>
> >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> >> >
> >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> >> >
> >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> >> car is going to be limited to 10 KW into the motors. Ecars are all
> >> about acceleration.
> >
> >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> The misunderstanding was yours. The nastiness too.

I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.

The OP is clearly confusing battery capacity with "drive power."

That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.

>
> The question made sense. Why a 10 KW inverter? The answer is probably,
> it's enough for a house backup and a bigger inverter would cost more.

That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.

>
> Battery cooling could be involved too, for a parked car.

Do batteries get all that hot in discharge?

On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > <bloggs.fred...@gmail.com> wrote:
> >
> > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > >> <bloggs.fred...@gmail.com> wrote:
> > >>
> > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > >> >>
> > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > >> >
> > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > >> >
> > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > >> about acceleration.
> > >
> > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > The misunderstanding was yours. The nastiness too.
> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.

3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.

>
> The OP is clearly confusing battery capacity with "drive power."
>
> That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> >
> > The question made sense. Why a 10 KW inverter? The answer is probably,
> > it's enough for a house backup and a bigger inverter would cost more.
> That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> >
> > Battery cooling could be involved too, for a parked car.
> Do batteries get all that hot in discharge?

Yes if you are discharging 50A. 20kW is around 50A @ 400V.

On Thursday, November 17, 2022 at 8:00:38 PM UTC-5, Fred Bloggs wrote:
> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > <bloggs.fred...@gmail.com> wrote:
> >
> > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > >> <bloggs.fred...@gmail.com> wrote:
> > >>
> > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > >> >>
> > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > >> >
> > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > >> >
> > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > >> about acceleration.
> > >
> > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > The misunderstanding was yours. The nastiness too.
> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
>
> The OP is clearly confusing battery capacity with "drive power."
>
> That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> >
> > The question made sense. Why a 10 KW inverter? The answer is probably,
> > it's enough for a house backup and a bigger inverter would cost more.
> That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> >
> > Battery cooling could be involved too, for a parked car.
> Do batteries get all that hot in discharge?

Absolutely, when you push the performance of the car. I saw a video of a German guy on the autobahn, driving as fast as he could. This involved not only acceleration, but deceleration, which ultimately overheated the car. I can't say for sure if it was the motor or battery, but the continued high current, in and out of the battery will absolutely raise the battery temperature and the cooling is important to the longevity of the battery.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
> On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > > <bloggs.fred...@gmail.com> wrote:
> > >
> > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > > >> <bloggs.fred...@gmail.com> wrote:
> > > >>
> > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > >> >>
> > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > >> >
> > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > >> >
> > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > > >> about acceleration.
> > > >
> > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > > The misunderstanding was yours. The nastiness too.
> > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.

3 miles per kWh is a good number for an electron guzzler like my X. The less bloated cars like the 3 and Y get more like 4 miles per kWh and I'd lump the Nissan Leaf into 4 miles per kWh group from everything I've heard.

> > The OP is clearly confusing battery capacity with "drive power."
> >
> > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> > >
> > > The question made sense. Why a 10 KW inverter? The answer is probably,
> > > it's enough for a house backup and a bigger inverter would cost more.
> > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> > >
> > > Battery cooling could be involved too, for a parked car.
> > Do batteries get all that hot in discharge?
> Yes if you are discharging 50A. 20kW is around 50A @ 400V.

Your Leaf has no battery cooling, right?

--

Rick C.

+-+ Get 1,000 miles of free Supercharging
+-+ Tesla referral code - https://ts.la/richard11209

On Thursday, November 17, 2022 at 5:30:44 PM UTC-8, Ricky wrote:
> On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
> > On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > > > <bloggs.fred...@gmail.com> wrote:
> > > >
> > > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > > > >> <bloggs.fred...@gmail.com> wrote:
> > > > >>
> > > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > > >> >>
> > > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > > >> >
> > > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > > >> >
> > > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > > > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > > > >> about acceleration.
> > > > >
> > > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > > > The misunderstanding was yours. The nastiness too.
> > > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> > 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.
> 3 miles per kWh is a good number for an electron guzzler like my X. The less bloated cars like the 3 and Y get more like 4 miles per kWh and I'd lump the Nissan Leaf into 4 miles per kWh group from everything I've heard.

So, 150kW drive power can get up to 600MPH.

> > > The OP is clearly confusing battery capacity with "drive power."
> > >
> > > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> > > >
> > > > The question made sense. Why a 10 KW inverter? The answer is probably,
> > > > it's enough for a house backup and a bigger inverter would cost more.
> > > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> > > >
> > > > Battery cooling could be involved too, for a parked car.
> > > Do batteries get all that hot in discharge?
> > Yes if you are discharging 50A. 20kW is around 50A @ 400V.
> Your Leaf has no battery cooling, right?

Not for my #1 battery, but #2 and #3 are A/C cooled.

On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
> On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > > <bloggs.fred...@gmail.com> wrote:
> > >
> > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > > >> <bloggs.fred...@gmail.com> wrote:
> > > >>
> > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > >> >>
> > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > >> >
> > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > >> >
> > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > > >> about acceleration.
> > > >
> > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > > The misunderstanding was yours. The nastiness too.
> > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.
> >
> > The OP is clearly confusing battery capacity with "drive power."
> >
> > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> > >
> > > The question made sense. Why a 10 KW inverter? The answer is probably,
> > > it's enough for a house backup and a bigger inverter would cost more.
> > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> > >
> > > Battery cooling could be involved too, for a parked car.
> > Do batteries get all that hot in discharge?
> Yes if you are discharging 50A. 20kW is around 50A @ 400V.

We're talking about a textbook discharge condition in the V2H home backup situation. The only dissipation mechanism I see outright is the I^2R loss in the battery internal resistance- and that should be ultra-minimized. Driving is a different story. Don't those electric motors constantly alternate between loading the battery and generating power from forward mechanical motion to recharge the battery? Charging the battery is a super-high power dissipation: battery terminal voltage x charging current (into the battery). Ideally discharge current that only leaves the battery causes zero power dissipation in the battery.

On Thursday, November 17, 2022 at 8:27:56 PM UTC-5, Ricky wrote:
> On Thursday, November 17, 2022 at 8:00:38 PM UTC-5, Fred Bloggs wrote:
> > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > > <bloggs.fred...@gmail.com> wrote:
> > >
> > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > > >> <bloggs.fred...@gmail.com> wrote:
> > > >>
> > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > >> >>
> > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > >> >
> > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > >> >
> > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > > >> about acceleration.
> > > >
> > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > > The misunderstanding was yours. The nastiness too.
> > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> >
> > The OP is clearly confusing battery capacity with "drive power."
> >
> > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> > >
> > > The question made sense. Why a 10 KW inverter? The answer is probably,
> > > it's enough for a house backup and a bigger inverter would cost more.
> > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> > >
> > > Battery cooling could be involved too, for a parked car.
> > Do batteries get all that hot in discharge?
> Absolutely, when you push the performance of the car. I saw a video of a German guy on the autobahn, driving as fast as he could. This involved not only acceleration, but deceleration, which ultimately overheated the car. I can't say for sure if it was the motor or battery, but the continued high current, in and out of the battery will absolutely raise the battery temperature and the cooling is important to the longevity of the battery.

Oh yeah- that fictitious autobahn with its 100 km/h speed limit that most Americans equate to 100 mph when it's actually 60.
The operative word is current into the battery- that will do it. I don't know the first thing about their motor, but I can see there might be surge currents in the windings (more I^2R losses) until the rotor spins up with enough counter emf in the rapid speed changing scenario. That will heat things up. Maybe something similar happens in V2H when the house abruptly turns on a heavy load. But that's a one shot transient and doesn't repeat with any kind frequency, hard to believe it will overheat the battery.

>
> --
>
> Rick C.
>
> +-- Get 1,000 miles of free Supercharging
> +-- Tesla referral code - https://ts.la/richard11209

On Thursday, November 17, 2022 at 10:47:56 PM UTC-5, Fred Bloggs wrote:
> On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
> > On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > > > <bloggs.fred...@gmail.com> wrote:
> > > >
> > > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > > > >> <bloggs.fred...@gmail.com> wrote:
> > > > >>
> > > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > > >> >>
> > > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > > >> >
> > > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > > >> >
> > > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > > > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > > > >> about acceleration.
> > > > >
> > > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > > > The misunderstanding was yours. The nastiness too.
> > > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> > 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.
> > >
> > > The OP is clearly confusing battery capacity with "drive power."
> > >
> > > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> > > >
> > > > The question made sense. Why a 10 KW inverter? The answer is probably,
> > > > it's enough for a house backup and a bigger inverter would cost more.
> > > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> > > >
> > > > Battery cooling could be involved too, for a parked car.
> > > Do batteries get all that hot in discharge?
> > Yes if you are discharging 50A. 20kW is around 50A @ 400V.
> We're talking about a textbook discharge condition in the V2H home backup situation. The only dissipation mechanism I see outright is the I^2R loss in the battery internal resistance- and that should be ultra-minimized. Driving is a different story. Don't those electric motors constantly alternate between loading the battery and generating power from forward mechanical motion to recharge the battery? Charging the battery is a super-high power dissipation: battery terminal voltage x charging current (into the battery). Ideally discharge current that only leaves the battery causes zero power dissipation in the battery.

??? The power of the battery voltage and current is either input to the battery for charging, or it's the power out to the circuit. The only dissipation would be losses which are very similar between charge and discharge. There are ohmic losses in the conductors in the battery, but there's also some loss in the chemistry, in that it requires diffusion. At higher currents the diffusion does not keep up as well as it might and the battery appears to have some extra losses.

There is zero reason to think that there are no losses on discharge. But there's no good way to measure the actual energy in the battery, so the losses on charge and discharge are hard to separate. I suppose you can consider the energy to be the useful coulombs in the battery, times the open circuit voltage. The voltage while discharging will be lowered by the net losses of discharge, in a similar manner to how the voltage when charging will be higher than the open circuit voltage, so that increase represents the losses of charging.

It is certainly not reasonable to consider that the conductors have losses in charging and none when discharging.

--

Rick C.

++- Get 1,000 miles of free Supercharging
++- Tesla referral code - https://ts.la/richard11209

On Thursday, November 17, 2022 at 10:57:43 PM UTC-5, Fred Bloggs wrote:
> On Thursday, November 17, 2022 at 8:27:56 PM UTC-5, Ricky wrote:
> > On Thursday, November 17, 2022 at 8:00:38 PM UTC-5, Fred Bloggs wrote:
> > > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > > > <bloggs.fred...@gmail.com> wrote:
> > > >
> > > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > > > >> <bloggs.fred...@gmail.com> wrote:
> > > > >>
> > > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > > >> >>
> > > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > > >> >
> > > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > > >> >
> > > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > > > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > > > >> about acceleration.
> > > > >
> > > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > > > The misunderstanding was yours. The nastiness too.
> > > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> > >
> > > The OP is clearly confusing battery capacity with "drive power."
> > >
> > > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
> > > >
> > > > The question made sense. Why a 10 KW inverter? The answer is probably,
> > > > it's enough for a house backup and a bigger inverter would cost more.
> > > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
> > > >
> > > > Battery cooling could be involved too, for a parked car.
> > > Do batteries get all that hot in discharge?
> > Absolutely, when you push the performance of the car. I saw a video of a German guy on the autobahn, driving as fast as he could. This involved not only acceleration, but deceleration, which ultimately overheated the car. I can't say for sure if it was the motor or battery, but the continued high current, in and out of the battery will absolutely raise the battery temperature and the cooling is important to the longevity of the battery.
> Oh yeah- that fictitious autobahn with its 100 km/h speed limit that most Americans equate to 100 mph when it's actually 60.
> The operative word is current into the battery- that will do it. I don't know the first thing about their motor, but I can see there might be surge currents in the windings (more I^2R losses) until the rotor spins up with enough counter emf in the rapid speed changing scenario. That will heat things up. Maybe something similar happens in V2H when the house abruptly turns on a heavy load. But that's a one shot transient and doesn't repeat with any kind frequency, hard to believe it will overheat the battery.

Hmmm... There are always I2R losses in the motor. You don't need to worry with the details of "spinning up". The more power the motor is handling, the higher the current and the more I2R losses. Notice the '2' in I2R? The waste power goes up with the square of the current. So higher road speeds, and especially accelerating and decelerating will heat up the motor and battery quickly.

--

Rick C.

+++ Get 1,000 miles of free Supercharging
+++ Tesla referral code - https://ts.la/richard11209

On 18/11/2022 01:36, Ed Lee wrote:
> On Thursday, November 17, 2022 at 5:30:44 PM UTC-8, Ricky wrote:
>> On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
>>> On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
>>>> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
>>>>> On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
>>>>> <bloggs.fred...@gmail.com> wrote:
>>>>>
>>>>>> On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
>>>>>>> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
>>>>>>> <bloggs.fred...@gmail.com> wrote:
>>>>>>>
>>>>>>>> On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
>>>>>>>>> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
>>>>>>>>>
>>>>>>>>> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
>>>>>>>>
>>>>>>>> You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
>>>>>>>>
>>>>>>> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
>>>>>>> car is going to be limited to 10 KW into the motors. Ecars are all
>>>>>>> about acceleration.
>>>>>>
>>>>>> That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
>>>>> The misunderstanding was yours. The nastiness too.
>>>> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
>>> 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.
>> 3 miles per kWh is a good number for an electron guzzler like my X. The less bloated cars like the 3 and Y get more like 4 miles per kWh and I'd lump the Nissan Leaf into 4 miles per kWh group from everything I've heard.
>
> So, 150kW drive power can get up to 600MPH.

Air resistance causes drag forces which robs power as the cube of
velocity becomes distinctly non-negligible from 60mph upwards so you are
being rather over optimistic there.

https://en.wikipedia.org/wiki/Drag_(physics)

The 80kW or 150kW is so they can claim 100Hp or 180Hp and have 0-60
times that are in the supercar league. It tends to wear the tyres out if
you spend too much time going from 0 to 60mph in the shortest time.

--
Regards,
Martin Brown

On Friday, November 18, 2022 at 3:17:18 AM UTC-8, Martin Brown wrote:
> On 18/11/2022 01:36, Ed Lee wrote:
> > On Thursday, November 17, 2022 at 5:30:44 PM UTC-8, Ricky wrote:
> >> On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
> >>> On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> >>>> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> >>>>> On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> >>>>> <bloggs.fred...@gmail.com> wrote:
> >>>>>
> >>>>>> On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> >>>>>>> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> >>>>>>> <bloggs.fred...@gmail.com> wrote:
> >>>>>>>
> >>>>>>>> On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> >>>>>>>>> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> >>>>>>>>>
> >>>>>>>>> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> >>>>>>>>
> >>>>>>>> You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> >>>>>>>>
> >>>>>>> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> >>>>>>> car is going to be limited to 10 KW into the motors. Ecars are all
> >>>>>>> about acceleration.
> >>>>>>
> >>>>>> That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> >>>>> The misunderstanding was yours. The nastiness too.
> >>>> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> >>> 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.
> >> 3 miles per kWh is a good number for an electron guzzler like my X. The less bloated cars like the 3 and Y get more like 4 miles per kWh and I'd lump the Nissan Leaf into 4 miles per kWh group from everything I've heard.
> >
> > So, 150kW drive power can get up to 600MPH.
> Air resistance causes drag forces which robs power as the cube of
> velocity becomes distinctly non-negligible from 60mph upwards so you are
> being rather over optimistic there.
>
> https://en.wikipedia.org/wiki/Drag_(physics)
>
> The 80kW or 150kW is so they can claim 100Hp or 180Hp and have 0-60
> times that are in the supercar league. It tends to wear the tyres out if
> you spend too much time going from 0 to 60mph in the shortest time.

That's my point exactly. Anything over 50kW drive (motor) is just theoretical (marketing).

On Friday, November 18, 2022 at 6:38:59 AM UTC-5, Ed Lee wrote:
> On Friday, November 18, 2022 at 3:17:18 AM UTC-8, Martin Brown wrote:
> > On 18/11/2022 01:36, Ed Lee wrote:
> > > On Thursday, November 17, 2022 at 5:30:44 PM UTC-8, Ricky wrote:
> > >> On Thursday, November 17, 2022 at 8:18:50 PM UTC-5, Ed Lee wrote:
> > >>> On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > >>>> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > >>>>> On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > >>>>> <bloggs.fred...@gmail.com> wrote:
> > >>>>>
> > >>>>>> On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > >>>>>>> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > >>>>>>> <bloggs.fred...@gmail.com> wrote:
> > >>>>>>>
> > >>>>>>>> On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > >>>>>>>>> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > >>>>>>>>>
> > >>>>>>>>> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > >>>>>>>>
> > >>>>>>>> You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > >>>>>>>>
> > >>>>>>> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > >>>>>>> car is going to be limited to 10 KW into the motors. Ecars are all
> > >>>>>>> about acceleration.
> > >>>>>>
> > >>>>>> That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > >>>>> The misunderstanding was yours. The nastiness too.
> > >>>> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> > >>> 3 miles per kwhr is a good rule of thumb. So, if you need to drive 60MPH, then you need around 20kW drive power. I don't know why people need 150kW, unless they are driving 450MPH.
> > >> 3 miles per kWh is a good number for an electron guzzler like my X. The less bloated cars like the 3 and Y get more like 4 miles per kWh and I'd lump the Nissan Leaf into 4 miles per kWh group from everything I've heard.
> > >
> > > So, 150kW drive power can get up to 600MPH.
> > Air resistance causes drag forces which robs power as the cube of
> > velocity becomes distinctly non-negligible from 60mph upwards so you are
> > being rather over optimistic there.
> >
> > https://en.wikipedia.org/wiki/Drag_(physics)
> >
> > The 80kW or 150kW is so they can claim 100Hp or 180Hp and have 0-60
> > times that are in the supercar league. It tends to wear the tyres out if
> > you spend too much time going from 0 to 60mph in the shortest time.
> That's my point exactly. Anything over 50kW drive (motor) is just theoretical (marketing).

The carmakers put lots of power in a car, so they can pass on hills and such. It has been more than once I've put my foot on the floor to pass a car.

--

Rick C.

--+- Get 1,000 miles of free Supercharging
--+- Tesla referral code - https://ts.la/richard11209

On Thursday, November 17, 2022 at 5:34:31 AM UTC-8, Fred Bloggs wrote:
> On Thursday, November 17, 2022 at 8:17:58 AM UTC-5, Commander Kinsey wrote:
> > On Thu, 17 Nov 2022 13:03:57 -0000, Fred Bloggs <bloggs.fred...@gmail.com> wrote:
> >
> > > On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > >>
> > >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > >
> > > You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > >
> > > Here is an authoritative overview:
> > > https://theconversation.com/can-my-electric-car-power-my-house-not-yet-for-most-drivers-but-vehicle-to-home-charging-is-coming-163332
> > >
> > > News of a work in progress to make home backup routine with no special equipment required:
> > > https://www.atlasevhub.com/weekly_digest/here-if-you-need-evs-as-backup-batteries/
> > >
> > > The cost for equipment to do that is top dollar because they sell so few. There's no logical connection between present cost and a hypothetical mass produced product.
> > Rewrite all that considering I know the difference between power and energy, I have a fucking physics degree. When I said 80kW I meant 80kW, not 80kWh. Do you seriously think a car motor only draws 10kW?
> Your so-called degree was a woefully inadequate preparation for dealing with reality if you have to ask such a stupid question.

Notice that Fred chooses to insult RATHER than answer the question, begging the question: does Fred not know the answer? Think about it, one horsepower is 750W, so 10KW is 13.3; do you REALLY think that a car as heavy as the Tesla S can be accelerated from zero to 60mph by a THIRTEEN HORSEPOWER MOTOR? OF COURSE NOT! In fact, the Tesla S is roughly 360-470 hp depending on the variant (60, 85 or P85). Do the math.

On Friday, November 18, 2022 at 8:40:08 PM UTC-5, Flyguy wrote:
> On Thursday, November 17, 2022 at 5:34:31 AM UTC-8, Fred Bloggs wrote:
> > On Thursday, November 17, 2022 at 8:17:58 AM UTC-5, Commander Kinsey wrote:
> > > On Thu, 17 Nov 2022 13:03:57 -0000, Fred Bloggs <bloggs.fred...@gmail..com> wrote:
> > >
> > > > On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > > >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > > >>
> > > >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > > >
> > > > You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > > >
> > > > Here is an authoritative overview:
> > > > https://theconversation.com/can-my-electric-car-power-my-house-not-yet-for-most-drivers-but-vehicle-to-home-charging-is-coming-163332
> > > >
> > > > News of a work in progress to make home backup routine with no special equipment required:
> > > > https://www.atlasevhub.com/weekly_digest/here-if-you-need-evs-as-backup-batteries/
> > > >
> > > > The cost for equipment to do that is top dollar because they sell so few. There's no logical connection between present cost and a hypothetical mass produced product.
> > > Rewrite all that considering I know the difference between power and energy, I have a fucking physics degree. When I said 80kW I meant 80kW, not 80kWh. Do you seriously think a car motor only draws 10kW?
> > Your so-called degree was a woefully inadequate preparation for dealing with reality if you have to ask such a stupid question.
>
> Notice that Fred chooses to insult RATHER than answer the question, begging the question: does Fred not know the answer? Think about it, one horsepower is 750W, so 10KW is 13.3; do you REALLY think that a car as heavy as the Tesla S can be accelerated from zero to 60mph by a THIRTEEN HORSEPOWER MOTOR? OF COURSE NOT! In fact, the Tesla S is roughly 360-470 hp depending on the variant (60, 85 or P85). Do the math.

You're talking about two different types of power ratings, peak and sustained. What little I can find about the Tesla EV is that later models can develop 700 HP peak for the wow effect of fast accelerations. Try to maintain it, assuming some automatic control doesn't kick in, and you trip the battery ( and/or even the motor maybe) overcurrent protection ( hopefully it requires manual reset so any fool who does this has to get off the road immediately). The latest Tesla model has come down a bit to a 100kWh battery capacity, the reason being a more efficient drive train with less losses, making the slightly lower capacity battery sufficient for their performance requirements. The engineers and technical management who designed these products are obviously very smart and capable. And when they decide a bidirectional charger for V2H at 10kWh is sufficient, then that means it's sufficient, they didn't just pull that number out of a hat. There are bigger issues at play here than just designing the vehicle itself. If someone doesn't like it, then let them build their own battery pack and inverter. Good luck with that.

On Thu, 17 Nov 2022 20:58:26 -0000, John Larkin <jlarkin@highlandsnipmetechnology.com> wrote:

> On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> <bloggs.fredbloggs.fred@gmail.com> wrote:
>
>> On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
>>> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
>>> <bloggs.fred...@gmail.com> wrote:
>>>
>>> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
>>> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
>>> >>
>>> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
>>> >
>>> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
>>> >
>>> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
>>> car is going to be limited to 10 KW into the motors. Ecars are all
>>> about acceleration.
>>
>> That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
>
> The misunderstanding was yours. The nastiness too.
>
> The question made sense. Why a 10 KW inverter? The answer is probably,
> it's enough for a house backup and a bigger inverter would cost more.
>
> Battery cooling could be involved too, for a parked car.

At last, the answer. Instead of saying "continuous and peak power output" they said "backup and driving mode". So either it's a continuous current draw problem, or as you said a matter of cooling.

On Fri, 18 Nov 2022 03:57:39 -0000, Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:

> On Thursday, November 17, 2022 at 8:27:56 PM UTC-5, Ricky wrote:
>> On Thursday, November 17, 2022 at 8:00:38 PM UTC-5, Fred Bloggs wrote:
>> > On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
>> > > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
>> > > <bloggs.fred...@gmail.com> wrote:
>> > >
>> > > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
>> > > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
>> > > >> <bloggs.fred...@gmail.com> wrote:
>> > > >>
>> > > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
>> > > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
>> > > >> >>
>> > > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
>> > > >> >
>> > > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
>> > > >> >
>> > > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
>> > > >> car is going to be limited to 10 KW into the motors. Ecars are all
>> > > >> about acceleration.
>> > > >
>> > > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
>> > > The misunderstanding was yours. The nastiness too.
>> > I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
>> >
>> > The OP is clearly confusing battery capacity with "drive power."
>> >
>> > That big Ford truck only puts out 2.4kW with its V2H bidirectional charger, with plans to maybe introduce one with 9.6kW sometime in the future. And even the small one adds thousands to the price of the vehicle. They're not going to waste a bunch of money making something people won't buy in the volume necessary to make a profit.
>> > >
>> > > The question made sense. Why a 10 KW inverter? The answer is probably,
>> > > it's enough for a house backup and a bigger inverter would cost more.
>> > That Ford thing wouldn't even turn over a 2 ton a/c. Looks like they just gave up powering the big stuff. Looks like they're going for 30 hours continuous at rated backup peak and the homeowner can take if from there, settling for less or more, it's up to them how they load or unload it.
>> > >
>> > > Battery cooling could be involved too, for a parked car.
>> > Do batteries get all that hot in discharge?
>> Absolutely, when you push the performance of the car. I saw a video of a German guy on the autobahn, driving as fast as he could. This involved not only acceleration, but deceleration, which ultimately overheated the car. I can't say for sure if it was the motor or battery, but the continued high current, in and out of the battery will absolutely raise the battery temperature and the cooling is important to the longevity of the battery.
>
> Oh yeah- that fictitious autobahn with its 100 km/h speed limit

WTF? Autobahns are famous for NO speed limit at all.

> that most Americans equate to 100 mph when it's actually 60.

Nobody obeys limits. Well maybe about 2/3rd of folk. But a high proportion ignore it.

On Sunday, November 27, 2022 at 5:27:49 PM UTC-8, Commander Kinsey wrote:
> On Fri, 18 Nov 2022 01:16:29 -0000, Ed Lee <edward....@gmail.com> wrote:
>
> > On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> >> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> >> > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> >> > <bloggs.fred...@gmail.com> wrote:
> >> >
> >> > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> >> > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> >> > >> <bloggs.fred...@gmail.com> wrote:
> >> > >>
> >> > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> >> > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> >> > >> >>
> >> > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> >> > >> >
> >> > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> >> > >> >
> >> > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> >> > >> car is going to be limited to 10 KW into the motors. Ecars are all
> >> > >> about acceleration.
> >> > >
> >> > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> >> > The misunderstanding was yours. The nastiness too.
> >> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> >
> > 3 miles per kwhr is a good rule of thumb.
>
> Jesus. You meant 3 mph per kW. Wrong twice in the same sentence.

You are double wrong in EV jargon. Miles per kwhr is the standard language for EV efficiency. Ask anybody who drives EV, and i bet you don't.

On Sunday, November 27, 2022 at 5:54:41 PM UTC-8, Commander Kinsey wrote:
> On Mon, 28 Nov 2022 01:41:18 -0000, Ed Lee <edward....@gmail.com> wrote:
>
> > On Sunday, November 27, 2022 at 5:27:49 PM UTC-8, Commander Kinsey wrote:
> >> On Fri, 18 Nov 2022 01:16:29 -0000, Ed Lee <edward....@gmail.com> wrote:
> >>
> >> > On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> >> >> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> >> >> > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> >> >> > <bloggs.fred...@gmail.com> wrote:
> >> >> >
> >> >> > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> >> >> > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> >> >> > >> <bloggs.fred...@gmail.com> wrote:
> >> >> > >>
> >> >> > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> >> >> > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> >> >> > >> >>
> >> >> > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> >> >> > >> >
> >> >> > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> >> >> > >> >
> >> >> > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> >> >> > >> car is going to be limited to 10 KW into the motors. Ecars are all
> >> >> > >> about acceleration.
> >> >> > >
> >> >> > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> >> >> > The misunderstanding was yours. The nastiness too.
> >> >> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> >> >
> >> > 3 miles per kwhr is a good rule of thumb.
> >>
> >> Jesus. You meant 3 mph per kW. Wrong twice in the same sentence.
> >
> > You are double wrong in EV jargon. Miles per kwhr is the standard language for EV efficiency. Ask anybody who drives EV, and i bet you don't.
> You were discussing (in the bit you snipped from your own text!) how speed was related to motor/battery power. Yet you wrote how distance travelled was related to battery capacity. Completely a different thing.

Not really. 3 to 4 mi/kwhr is the standard display on screen. We, the EV drivers, are all well familiar with that number. From driving 60 miles in an hour, we can determine that 20 kwhr are consumed. So, the average number of 3 MPH per KW is derivated.

On Sunday, November 27, 2022 at 9:41:22 PM UTC-4, Ed Lee wrote:
> On Sunday, November 27, 2022 at 5:27:49 PM UTC-8, Commander Kinsey wrote:
> > On Fri, 18 Nov 2022 01:16:29 -0000, Ed Lee <edward....@gmail.com> wrote:
> >
> > > On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > >> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > >> > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > >> > <bloggs.fred...@gmail.com> wrote:
> > >> >
> > >> > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > >> > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > >> > >> <bloggs.fred...@gmail.com> wrote:
> > >> > >>
> > >> > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > >> > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > >> > >> >>
> > >> > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > >> > >> >
> > >> > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > >> > >> >
> > >> > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > >> > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > >> > >> about acceleration.
> > >> > >
> > >> > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > >> > The misunderstanding was yours. The nastiness too.
> > >> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> > >
> > > 3 miles per kwhr is a good rule of thumb.
> >
> > Jesus. You meant 3 mph per kW. Wrong twice in the same sentence.
> You are double wrong in EV jargon. Miles per kwhr is the standard language for EV efficiency. Ask anybody who drives EV, and i bet you don't.

I wouldn't call it "efficiency". It is mileage, just like gasoline mileage, miles per gallon vs. miles per kWh.

I don't know why you respond to Kinky. He will never acknowledge when he is wrong. It's like wrestling a pig. You both get dirty, but the pig enjoys it.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

On Sunday, November 27, 2022 at 10:09:14 PM UTC-4, Ed Lee wrote:
> On Sunday, November 27, 2022 at 5:54:41 PM UTC-8, Commander Kinsey wrote:
> > On Mon, 28 Nov 2022 01:41:18 -0000, Ed Lee <edward....@gmail.com> wrote:
> >
> > > On Sunday, November 27, 2022 at 5:27:49 PM UTC-8, Commander Kinsey wrote:
> > >> On Fri, 18 Nov 2022 01:16:29 -0000, Ed Lee <edward....@gmail.com> wrote:
> > >>
> > >> > On Thursday, November 17, 2022 at 5:00:38 PM UTC-8, Fred Bloggs wrote:
> > >> >> On Thursday, November 17, 2022 at 3:58:36 PM UTC-5, John Larkin wrote:
> > >> >> > On Thu, 17 Nov 2022 10:32:33 -0800 (PST), Fred Bloggs
> > >> >> > <bloggs.fred...@gmail.com> wrote:
> > >> >> >
> > >> >> > >On Thursday, November 17, 2022 at 10:30:31 AM UTC-5, John Larkin wrote:
> > >> >> > >> On Thu, 17 Nov 2022 05:03:57 -0800 (PST), Fred Bloggs
> > >> >> > >> <bloggs.fred...@gmail.com> wrote:
> > >> >> > >>
> > >> >> > >> >On Thursday, November 17, 2022 at 4:27:46 AM UTC-5, Commander Kinsey wrote:
> > >> >> > >> >> If an EV has an output power of say 80kW to drive the motors when driving, why is the backup power (to power your house in a power outage) only about 10kW? It's the same battery!
> > >> >> > >> >>
> > >> >> > >> >> And why do people say it costs thousands of dollars to fit something to do this? Surely a 10kW invertor doesn't cost much, just something to make 400VDC into 240VAC. I'd say more like 500 dollars.
> > >> >> > >> >
> > >> >> > >> >You need to learn the difference between energy and power. The 80kW is really 80kWh(hours), a measure of energy stored in the battery. The 10kW is a measure of power which is the rate of energy extraction from the battery, usually specified in kW, kilo-watts, thousands of Watts. There is no logical connection between the two ratings. The engineering requirements of the battery EV application determines that.
> > >> >> > >> >
> > >> >> > >> He clearly said that the battery can deliver 80 KW of power. No 80 KWH
> > >> >> > >> car is going to be limited to 10 KW into the motors. Ecars are all
> > >> >> > >> about acceleration.
> > >> >> > >
> > >> >> > >That 80kW is quoted quite often as the battery capacity when they mean 80kWh of course. Without that as his fundamental misunderstanding, the question is senseless.
> > >> >> > The misunderstanding was yours. The nastiness too.
> > >> >> I have no misunderstanding. The manufacturers don't specify the "drive power" of the batteries in their EV. Why would the consumer need to know that? They do specify battery capacity of their EV because it gives the consumer an idea of expected range.
> > >> >
> > >> > 3 miles per kwhr is a good rule of thumb.
> > >>
> > >> Jesus. You meant 3 mph per kW. Wrong twice in the same sentence.
> > >
> > > You are double wrong in EV jargon. Miles per kwhr is the standard language for EV efficiency. Ask anybody who drives EV, and i bet you don't.
> > You were discussing (in the bit you snipped from your own text!) how speed was related to motor/battery power. Yet you wrote how distance travelled was related to battery capacity. Completely a different thing.
> Not really. 3 to 4 mi/kwhr is the standard display on screen. We, the EV drivers, are all well familiar with that number. From driving 60 miles in an hour, we can determine that 20 kwhr are consumed. So, the average number of 3 MPH per KW is derivated.

I thought the Leaf would get more like 4 m/kWr. My boat model X gets 3 m/kWh. The model 3 gets 4 m/kWh and some people claim closer to 5 m/kWr, I suppose their driving is less highway.

I think it's an issue of significant digits, but my car displays Wh/mi rather than m/kWh. Still, it's the same measurement and is typically around 333 kWh/mi, but does run higher when I'm hitting 70+.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209