Strange battery behaviour

[bonzo]

I got me a Lenovo T440P and the battery is behaving in a weird manner. IN normal operation/use means it needs charging either once or twice a day. I have accidently left it after the warning to re-charge, and it powers off, which the system doesnt like that much. But at least i know the warning is correct and not winding me up

But, every so often, the battery charge stays at 100% / 99% for a few days or more. The last time this happened was a couple of months ago, and its just started again. After 3 days, it has used 1% which i find odd.

The battery state of charge at bottom right cant be faking, because the laptop would have turned itself off, so it is really lasting that long. Its just that i dont understand why.

If i knew what it was doing, i'd keep it on that road as it would save me having to charge it every day or more.

 

[iraiguana]

The laptop turns the charger for the battery off when fully charged. It will then run off the mains supply, however, there is still a small load on the battery as the electronics never really are fully off, so the battery drains slowly. This is why it goes from 100% to 99%. At 99% the voltage has dropped slightly and so the charger is re-activated. This should be fairly common.

 

[bonzo]

Normal activity for this Lenovo is it needs charging 2 or 3 times a day for months at a time. Its only occasionally that it will keep nearly a full charge for 5 days, then it returns to normal. I dont understand why it randomly decides not to use much of its charge for maybe 5 days every couple of months