Most all racers charge at 5-6 amps any less and u get a pack that will run longer but, with less punch. The pack should not exceed 125 deg when finishing (warm to the touch almost hot) I use 3-4 mv for peak detection. First few charges u may need more dont exceed 6mv. Discharge 20-30 amps is standard with a cutoff of 5.4 v. Reciever packs charge at 1 amp.