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Hello,
I possess a T480 thinkpad,
- since one year, the dual battery was handled by discharging the external battery first, then the internal battery.
- since two days, this behaviour is *inverted*, the internal battery is discharged first, then the external one (which is an anti-design).
also, the external battery has endured 50 battery cycles, upower tells me that energy-full is 50% of energy-full-design, when previously it was approximately 98%.
I could use some help for this,
I tried so far :
downgrade to linux lts
checking bios settings
Last edited by BWV1000 (2023-05-18 12:28:45)
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The order of discharge is chosen by the charge controller on T480 thinkpads and not something you can edit from the OS iirc. The T470 and earlier models always discharged the external cells first, but the T480 models discharge the cell that's been through the fewest charge cycles first to try and spread the wear on the cells evenly. I have a T480 as well and it's constantly switching the discharge order between my standard external cell and my internal cell which are roughly the same age. I've got a much newer 61++ battery which always gets discharged before my internal cell because it's endured far fewer cycles.
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Thanks for your answer.
That's explaining the behavior.
Do you happen to know what could explain the fact that the energy-full value of the batterie has known a drastic drop in value in such a few time (i.e. from 98% to 50% of the design value in two days ?)
Last edited by BWV1000 (2023-05-14 10:53:21)
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How often does your battery go through a full charge cycle, from 100% down to 0%? Normally, your reported percentage mainly comes from the power being drawn from the battery being integrated over time, but this slowly drifts over time as the battery degrades and the errors from the voltage and current sensors not being perfectly accurate add up. However, there are fixed minimum and maximum voltages, so the calibration is reset at 100% and 0%. If your battery has never been fully discharged, but for some reason was a few days ago, maybe that would have caused a perceived "sudden" drop. That is not very likely because you probably haven't gone literally several years without discharging your battery to zero, and such a big gap between estimated and actual capacity would have caused your battery percentage to drop by a huge amount as the battery dies which you probably would have noticed, but it is theoretically possible.
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I usually set up a rule to stop battery charging at 80%. What you are saying makes sense. Nevertheless, after 52 battery cycles (as told by upower) the battery can do 50% of its factory performance regarding energy storage; the battery is defective isn't it ?
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Yes, stopping charging at 80% is a good idea because it greatly reduces degradation. You do have to charge it fully occasionally for calibration, but about once per month should be fine. Your battery should definitely not be at 50% health after 52 cycles. These days, they can do a few hundred cycles of 0-100 before reaching 80%, and even two months of being permanently at 100% (about the worst thing you can do to them) shouldn't destroy them that much.
You should probably do one or two more cycles before ruling the battery as bad immediately. Sometimes after an event like this, the battery will overcorrect to a too-low capacity and need another cycle to actually get the correct one. When I got my T580 used, the internal battery dropped from 85% to 60% and then went back up to 67%. I assume this is because the previous owner used that computer plugged in for the vast majority of its life, and the battery had just never been fully discharged for months until I got it. I also had an Acer Aspire die at about 20% and drop from about 80 to 60 and then go back to 67 at some point. So maybe at least some capacity will be recovered. Don't expect much, but maybe you'll get lucky.
I think you're right. Your battery is probably defective.
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Thanks for your answer.
I'll keep this thread unsolved until my battery has done two cycles from 100% to 0%, and when
this is done I will write a 'report' here.
I judge that this information will be useful to anyone having the same troubles with their batteries,
on top of the fact that this would lead to a true conclusion regarding my initial problem.
And..., unclear behaviors are so weird when it comes to computers that small "experiences" like this always produces good-value facts.
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That was spot on,
after a full cycle of both of the batteries, the max-capacity of BAT1 as notified by upower went from 50% to 91%.
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