Jeff Liebermann wrote:

> No, it's not. I guess I should be more specific. I would like to
> know why you find it necessary to test a LiIon cell in a charge range
> of zero to 20%, where literally every recommendation by the
> manufacturers declare that to be an RBI (really bad idea)?

I _know_ it's a really bad idea, which is _why_ I want to see what happens.

I got a handful of these phones for free, so I have _plenty_ to work with.
It's just a phone. Phones are a dime a dozen. They're a commodity.

This is a Samsung Galaxy A32-5G, which, even if I paid for it, is cheap.

People do drop tests all the time, don't they?
That's a really bad idea too. :)

> Looks that
> specs for any BMS (battery management system) found inside most LiIon
> battery packs. There is a feature that literally disconnects the cell
> if the terminal voltage goes below some value which usually works out
> to about 20% charge. Maybe this will help you understand the problem
> you're creating for yourself:
> "Lithium Ion Cell Operating Window"
> <https://www.mpoweruk.com/lithium_failures.htm>
> Notice that the "operating area" is between 20% and 90% SOC.

I designed microcontroller-based batter chargers as experimental tools back
in the 80's in graduate school but it has been a long time since then.

I've probably forgotten more than I learned by then, but my main point is
that I consider all smartphones merely a tool to play with to learn about.

If you don't do destructive testing, you won't learn as much as if you do.
(As an aside, you should see the destructive testing I did on the iPad!)

I take risks with the mobile devices all the time in order to learn more.

For example, I recently figured out a way to change my supposedly permanent
supposedly unique Google-supplied GSF ID, which may be the reason that
the Android 11 to Android 12 update on my Samsung deleted hundreds of apps.
*Have you ever tried to CHANGE your unique GSF ID on your Android device?*
<https://groups.google.com/g/comp.mobile.android/c/Ixl2uMSLADc>

>>So it's not just me who is curious what happens in the real world.
>
> Yes, but you are not the entire real world. Your currently
> undisclosed operating criteria is not the same as every user and
> certainly not the same as the cell phone manufacturer. The
> manufacturer wants big numbers because big number sell phones.
> Whatever it takes to produce big numbers balanced by cost and safety
> issues. Big numbers are rather useless if the phone catches fire in
> the owners pocket. So, the game of battery specmanship degenerates
> into squeezing as many watt-hours out of the battery as possible by
> any means deemed economical (and maybe reliable). Do it wrong, and
> you have a situation like Apple, where the phone had to be slowed down
> to produce a reasonable runtime as the battery aged. At that point,
> the user gets involved and tries to squeeze out as much power as
> possible. However, they can't because the manufacturer has already
> done that with a complexicated BMS algorithm. So the user looks to
> see what can be gained by breaking the safety rules. Good luck. If
> you are actually able to run the phone at extremely low SOC, then the
> manufacturer has screwed up and is selling an unsafe phone, battery,
> or both. What phone and battery are you using and I'll be sure to
> blacklist it.

It's the Samsung Galaxy A32-5G and it's the T-Mobile model SM A326U.

You'll see some of my experiments on the XDA Developers' forum:
<https://forum.xda-developers.com/f/samsung-galaxy-a32-5g.12145/>

>>I've always been curious about the best way to do almost any thing.
>>And destructive testing is a fantastic way to figure out what really
>>happens in the real world under real world conditions, even as you can't
>>hope to run a "consumers report" style full-fledged scientific
>>investigation with basic home equipment.
>
> Please note my domain name, LearnByDestroying.com. The intent is
> slightly different from yours. It's my contention that one does not
> understand how something works without first breaking it, and
> subsequently fixing it. Destructive testing, without subsequent
> understanding (and enlightenment) is useless.

Like you appear to do, I try to learn why things fail when they fail.

For my BMW, a lot of parts break, where I take them apart to find what
caused the failure, whether that's the FSU or the expansion tank.

You can't put that stuff back together, although I did try to reseat the
myriad "angel hair" wires inside the ABS control module, which are just
impossible to do without specialized machines.

Having said that, my cars are decades old where I fix everything I can,
even to the point of mounting and balancing my own tires at home, so if I
_can_ fix it after taking it apart, I will fix it after taking it apart.
<https://i.postimg.cc/zvvyL2tq/mount24.jpg> Analyze the wear
<https://i.postimg.cc/X7hcV3ps/mount26.jpg> Keep close track of wear
<https://i.postimg.cc/63Kc80x9/mount29.jpg> Watch wear over time
<https://i.postimg.cc/wTf1xnzJ/mount36.jpg> Inspect root causes
<https://i.postimg.cc/g004XCLW/mount37.jpg> Run experiments
<https://i.postimg.cc/g004XCLW/mount37.jpg> Gather more data
<https://i.postimg.cc/G3HWPtQg/mount39.jpg> Test your assumptions
<https://i.postimg.cc/8zVxVHVx/mount40.jpg> ID engineering principles
<https://i.postimg.cc/YqHVb5gY/mount33.jpg> Fix root cause
<https://i.postimg.cc/DwnjgJY3/mount08.jpg> Buy a new tire
<https://i.postimg.cc/FKfFwJ25/mount48.jpg> Break the bead
<https://i.postimg.cc/g004XCLW/mount37.jpg> Replace the valve
<https://i.postimg.cc/WzZW9MvT/mount07.jpg> Mount the tire
<https://i.postimg.cc/28JK2bFB/mount58.jpg> Balance the wheel
<https://i.postimg.cc/0NGXktgp/mount59.jpg> Recycle the carcass

Bear in mind it's difficult to find out why some wear patterns happen
simply because they are on perfectly well aligned vehicles sometimes.
<https://www.quora.com/When-turning-I-see-there-is-a-plus-camber-in-a-vehicle-Why>

>>Still... I try to learn... and destructive testing is part of learning.
>
> It's a tiny part but admittedly the fun part. It's lots of fun to
> blow things up. It's less fun, but more educational to understand how
> the device you just destroyed functions. When you destroy something
> (like your phone battery), do you take or record measurements? Do you
> record a video for an instant replay? Have you worked out in advance
> what you expect to happen? Do you look for anomalies? Do you own a
> data logger? How would blowing up a cell phone battery demonstrate
> anything if you don't know at what voltage (or SOC) and temperature it
> blew up? Did you put a plastic bag over the phone to capture any
> gasses (and flying glass) produced? Do you have a new battery or
> phone available for comparisons? Without these, all you've "learned"
> is how to blow up a battery or phone.

I can't disagree with anything you've said as I run experiments all day
every day, some of which are detailed (like those tire experiments) and
others aren't as detailed (as my phone battery experiments are).

>>When I was a kid, my dad kept a box of old "stuff" for me to take apart.
>
> Hint: I still act like I'm kid. I even take things apart BEFORE I
> try operating them.

The one thing really convenient about destructive autopsies is you don't
have to put anything back together. You just put it in the recycling bin.

>>Why does anyone run any experiment?
>
> Usually because they are suspicious of the established theories of
> operation and have reason to suspect that parts of the theories are
> wrong or badly understood.

Notice the tire experiments above where there is precious little
information on the Internet why all the cars that are perfectly aligned in
any given twisty road area wear the tires the exact same abnormal way.

Take a look at the Scotty Kilmer video below, and note particularly that
the photos I've been posting (which I've posted for years) are the _same_
as in Scotty Kilmer's videos (just look and you'll recognize my pictures!).
<https://youtu.be/i7alzjqmPQo>

This is a shot he took of my BMW tires, for example, with wear lined up:
<https://i.postimg.cc/HngnZR6h/scottykilmer.jpg> He stole my images! :)
--
I find it a testament to my thoroughness that Scotty Kilmer stole my photos
(which clearly are the same photos as I've been posting here all along).