2 for each class.
2wd buggy - 2 shorties,
tamiya mini - 2 nimh packs
tamiy tt-02 - 2 full sized 2s'
My cousin and fellow racer only uses one pack for each class, but he's not super competitive or has much mechanical sympathy so tends to charge his packs in the car between heats/finals. I prefer to give the batteries a chance to cool down, in the mini race meets his nimh cells are usually close to untouchable with the heat of constant charging/discharging, but its impossible to get him to see the benifit of having another pack as he's a consistent top 3 finisher, so maybe he knows something i don't
