Originally Posted by Tommy R

Maybe he's referring to just a loss of punch, as opposed to the battery merely lasting the duration of the race? I don't know either way, but just pointing out another possibility.

For the track I run at, my car is pretty good clearing a particular jump earlier in the race, but as it wears on I lose just enough punch that that same jump gets more and more risky due to the slight decrease in power. Maybe that's similar to what the OP was experiencing?