[ltp] T480s, battery state jumping from fully-charged to charging while plugged in, battery LED doesn't change

[Kevin Locke]

On Tue, 2022-06-14 at 20:58 -0500, Rubin Abdi wrote:
> If I'm being too noisy in the void please let me know.

I for one appreciate hearing about your investigation and think it
could be useful for others with similar issues in the future.  I
apologize that I don't have much useful input to provide

> [...]
> Here are two samples from upower:
> 
>     state:               fully-charged
>     warning-level:       none
>     energy:              51.31 Wh
>     energy-empty:        0 Wh
>     energy-full:         53.09 Wh
>     energy-full-design:  57 Wh
>     energy-rate:         3.085 W
>     voltage:             12.988 V
>     charge-cycles:       14
>     percentage:          96%
>     capacity:            93.1404%
> 
>     state:               charging
>     warning-level:       none
>     energy:              51.32 Wh
>     energy-empty:        0 Wh
>     energy-full:         53.09 Wh
>     energy-full-design:  57 Wh
>     energy-rate:         3.769 W
>     voltage:             12.909 V
>     charge-cycles:       14
>     time to full:        28.2 minutes
>     percentage:          96%
>     capacity:            93.1404%
> 
> I dumped "96" into
> /sys/class/power_supply/BAT0/charge_control_end_threshold and it's stopped
> flipping. But I thought this would tune 0%-96% to scale what my battery
> meter would display with 0%-100%, and not just stop charging at 96%
> displayed on the meter.
> 
> So I guess my question is, am I doing this correctly, or is the root of my
> issue elsewhere? If I hadn't already e-wasted the old battery I would pop
> that in for a test.

I think you are on the right track.  Setting an end threshold is a
good idea, even if it just reduces the annoyance.  My uneducated guess
is that the problem is in the battery.  I don't know whether it might
be a faulty cell with a high self-discharge rate, or the fuel gauge IC
incorrectly deciding to charge (e.g. due to incorrect energy-full), or
something else.

If you can try using a different battery, that'd probably be the
easiest way to confirm.  Since your old battery isn't available,
perhaps a nearby computer repair shop, IT department, or user group
could lend you one for a few minutes to test?

Good luck!  Curious to hear about what you find.

Cheers,
Kevin