Are you just using two drive motor's like drills or similar?
If so, I would try a 30-40A fuse inline (standard automotive fuses). Wayne uses the same size lipo in Basher with drill motor's using a 30A fuse and has never had a problem.
Wiring in your robot will play a bigger part of tech-checking than in general, so it's worth making sure all your connections are good and no wire chaffing.