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Unaccounted-for battery draw on X210?

Old(er) Thinkpads with New(er) Intestines: X62 / T50 / T70 / etc.
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Unaccounted-for battery draw on X210?

#1 Post by flyingfishfinger » Tue Jan 14, 2020 1:15 am

Maybe a silly question but this has me stumped. I'm currently using coreboot with vladisslav's EC.

I've got a 9-cell X201 (8.6Ah nominal) battery I'm using. Pretty old, according to Battery Bar it's 17.5% degraded. That should put it around 70Ah, subtract another 10 for fudging and bad specs, which at 11.1V is (handwave handwave) 60Wh.

In one scenario, PowerTop under Ubuntu reported 10W usage and gave me an estimated 4 and something hours remaining. That's already a bit short given the above.

When I came back 2 hours later I had a 4% warning and imminently after the machine shut down. Even assuming capacity detection is still borked with this EC, I got the 17% degradation figure from a while back when I did a manual discharge test on all of my cells (and Battery Bar more or less agrees). Therefore even if Ubuntu's 4 hour estimate is based on wrong data, the math still more or less checks out.

So, something is off here. What am I missing?


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Re: Unaccounted-for battery draw on X210?

#2 Post by L29Ah » Tue Jan 14, 2020 1:52 am

AFAIU, capacity is reported by the battery itself, and is subject to the aftermarket battery BMS wonkiness and generally poor quality of the cells themselves.

> 8.6Ah nominal

I don't believe such batteries exist on the market these days. Probably 6-7A*h, the usual capacity of cheap LiIon 18650 cells. The original ones would have degraded even further, especially on higher currents.
51nb X210 with community EC mod, me_cleaner and recelled 99W*h battery; X230 with coreboot, me_cleaner and nitrocaster's FHD mod as a backup; R500 for guests; T60 just for the looks.

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