I just recently installed a small 55 amp powermaster for my drag race only car. Went from having to charge battery every time I came off the track to forgot there was a battery in the car. It stated where the rpm was going to charge and it was correct. Yes these don't charge till 1100-1200 rpm I charge going down the track and return road. Didn't lose any performance works fine for my setup. 340 Auto electric fan, electric water pump, Elec fuel pump, line loc. Tail/ brake lights just a race car I like it. But a bigger engine more electrics everybody is different. Im glad I did should have done it sooner.