So I ordered a replacement battery from a big eBay seller branded #CameronSino, as I could not find a genuine one anywhere.
But after the laptop is in my bag for some hours, I can turn on the laptop but there is no left capacity reportet. After reinstalling the battery, everything will be fine.
Anybody has an idea which manufacturer to chose? #Lenovo #Thinkpad #P71
Not an answer, but make sure that your laptop is really off when you put it in your bag. My guess is that it’s somehow overheating in there, and the battery shuts off for safety.
Battery does not drain, also I always shut down properly. Still I will double check next time.