Better chargers can charge above 6 amps. This can make a real difference in time. Lower price chargers rarely charge above 6 amps. 10 amps really separates them. A lot of people at the track are using the Hi Tech quad and very satisfied with it, for charging 2s batteries @ 6 amps. If you go 3s and higher, you will need a 10 amp charger, or higher.