I actually am on my original battery, it only has like 25 or 30 cycles because I only used it to play games so it was always plugged in. Before I installed the SSD, I tested the battery and got through 1.75 playthroughs* of Beetlejuice on full brightness!
The model I have is the early 2011, so it’s got an ancient i7 and a dedicated GPU. On the most recent OSX version it’ll take, the GPU doesn’t appear to be working though… which is fine, because I just use it to browse stuff and store a million pictures.