[protoserge]

I would suggest buying legal batteries (MK and Genesis) and reserve them for competition use and the "replacement batteries" for use when training drivers, giving demos, and using in the shop. This will allow you to use your competition batteries for at least 3-5 years (be sure you keep all batteries charged every 30-60 days during the offseason).

The "replacement/comparable" batteries are equivalent to the legal batteries and are half the price.

I'd also suggest buying Battery Beak. They are a great thing to have to verify your battery is charged and in good health. In Rebound Rumble, we found that one match was using 1% battery charge, so we did not need as many batteries as we originally thought or charge them after every match.