Originally Posted by
skeasor
If I remember correctly, higher mah will give you a longer run time. C rating is the charging rate, discharging rate and internal resistance. I'm not sure how much draw comes from the stock motor of the b4.1, but I'm sure it isn't much.
You are correct, mah gives you the run time. The C rating is used for discharge rate. Basically your continuous discharge is calculated by mah * C rating. Your peak discharge is mah * peakC rating.
On the b4.1 i am sure anything over a true 20c would be fine. However its best to buy the highest C rated batteries, since they will make a difference in other cars.