I bought a used Thinkpad and noticed the battery drains in a few minutes. Litterally 5 minutes or so.

Is there anything that could be doing this instead of just the batteries being shot? I know Thinkpads, and even after extensive use they shouldnt be doing this. They have two batteries, one internal and one external.
I once had another laptop that had some weird driver / BIOS thing that made the battery drain in dog years