Originally Posted by biz77

I don't think anyone will disagree with you that you are putting the same 2,500 mah back into your battery whether you are charging at 5 amps over 30 minutes or at 40 amps over 3 minutes and 45 seconds. The debate is that if you have multiple people charging at 40 amps you quickly run out of current capability on the main AC circuit.

For example:
40 amp charge on a 2s battery is a peak draw of:
40 amps * 8.4 volts = 336 watts
Assume 90% efficiency in your charger and power supply: 336 watts * 1.10 = 369.6 watts
396.6 watts / 120 volts = 3.305 amps
If you have a 20-amp breaker:
20/3.305 = 6.05
This means a 120 volt 20-amp breaker will be at its limit with just 6 people charging a 2s battery at 40 amps.

If everyone was using a 5-amp charge rate the math becomes:
5 amps * 8.4 volts = 42 watts
90% charger/PS efficiency: 42 watts * 1.10 = 46.2 watts
46.2 watts / 120 volts = .385 amps
With a 20-amp breaker:
20/.385 = 51.948
Almost 52 people can run on the same 20-amp circuit in this scenario.