Batteries ripping out of the cars is totally different than something punchuring through a body etc to get to the lipo pack. That's a battery holding issue... which can be addressed and prevented.
You would have to basicly break the car in half like craps said... to seriously endanger the battery.
You are more likely to get in a wreck on the way to the track than you are to have a lipo pack get destroyed in the car.... that's all I'm saying. Make sure the pack is mounted very securely and call it good.
I have never seen a battery bar get knocked off, sorry
But I have seen three cells of a 6 cell pack hang completely out of a T4 during a race... due to the design of the battery mounting system. After that we came up with a fix for it... never will happen again. He finished the race btw...