this post was submitted on 26 Jul 2024
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What voltage does your thinkpad charge the battery to? (lemmy.ml)
submitted 3 months ago* (last edited 3 months ago) by fl42v@lemmy.ml to c/thinkpad@lemmy.ml
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I've replaced cells in my fake battery a few days ago, and while recalibrating the bms I noticed what looked like it trying to overcharge the cells -- the voltage went up to above 12.6v and stabilized at around 12.9 (which amounts to ~4.3v per cell and is 0.1v above what cell manufacturers generally recommend). Idk if that's the intended behavior or clone manufacturers trying to shorten the lifetime of said batteries, so if the owners with genuine batteries can provide that info, I'd really appreciate it.

On linux, you can check this with cat /sys/class/power_supply/BAT*/voltage_now (as your usual user, those files are world-readable); not sure about windows, tho.

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[โ€“] Jumuta@sh.itjust.works 1 points 3 months ago (1 children)

Oh my god thank you, that's amazing. I had no idea you could use i2c with the vga port.

Also, I run the t430 with Coreboot, but does this solution only work on 30 series?

[โ€“] fl42v@lemmy.ml 1 points 3 months ago* (last edited 3 months ago)

I guess so, but you should check which controller is used on your bms. This guide targets bq8030, as mentioned in the readme

Edit: also, my bad: it looks like the guide doesn't show how to change the battery capacity, so recalibration is also necessary (alternatively, you can look for the values reported by /sys/class/power_supply/BAT*/energy_full{,design} in the dumped firmware and change them. However, the script is useful if your bms locked itself (in this case replacing/shorting the fuse might also be necessary, as some bms-es try to blow it when locking)