Thinkpads Forum

Hi guys. I'm experiencing an issue with my X220. When using the laptop and going over a certain level, the battery jumps to a low charge value (such as 6%) and Windows warns me about plugging it to power.

Normally, I would assume this is one of the cells inside the battery pack failing but I read this:

There is some problem with the Lenovo Battery/UEFI Firmware. The Battery Manager on Window or tp_sampi module under linux is usually configured to extend the batteries life by only charging it to 85%.

But discharging the battery from 85% (eventually somehow related to hibernate) can cause the batteries charge counter to drift off more and more over time. The result is a sudden drop of battery life at some point (in my case, at around 45% it suddenly drops tp 6%). The battery reports 85% way too early.

People reported that setting the thresholds to 100% mostly resolved the problem after a few full charge cycles.

It seems legit. My laptop is recent and the battery is almost new. When I purchased it it didn't have any special charging threshold (the normal 96-100%) and it worked fine. Then I manually set it to 50-80% and is when it started to show this issue.

One weird thing I noticed from the begining is that the design capacity is 62 WHr but after some calibration it says 66 WHr. That makes me to believe that there is actually a problem with the charging firmware on this model (or potentially, in all UEFI models).

I'm going to revert back to 100% to see if the problem gets fixed. If it does, I think it's time to report this to Lenovo.

It is a bug, confirmed. How do I report tis to Lenovo...?

Post it on their forum and drop me a PM here once you do so...