I bought my son the Redcat Terremoto 10 V2 last year and got him an extra 5000 battery (Hexfly), the 3200 that came with the vehicle has completely died (will not recharge). I'm looking to get him a couple more batteries and noticed that some of the ones I'm looking at have a different "C" rating. what is the difference and what impact does this have on the performance or on the electronics of the car?