Yes it does. You're confusing energy vs power. Power is energy per unit of time, thus if you charge in less time you're using more power.

I think you mean the current draw is vastly different for 400 watts at 12 volts and 400 watt at 120 volts? 400 watts is 400 watts no matter the voltage and current used to get there.

I'm far more concerned with the various mystery brews people use on tires.

I remember hooking a battery up to my motor, after every run in dirt, and dipping in pure trichloroethane to clean it. Brushed motor and sealed, back in the day. Nasty stuff. Probably already cost me some brain cells.

And Power is measured in Watts. The dimension of power is energy divided by time. So in basic terms, someone charging at 5 amps for 30 minutes should about equil someone charging at 40 amps for less than 4 minutes. At least in the ballpark. So a RC race track where everyone charged at 40 amps would use the same power as a race track where everyone charged at 5 amps. Or if 1 person eats a foot long in 5 minutes equals 2 people eating 2 6" in 2.5 minutes. Same Footlong.

No, if everyone is charging at 40 amps they're using more power. They're using the same energy overall compared to a lower amp draw. The mains wiring, fuse boxes etc aren't rated for energy usage, they're rated for current draw.

To break it down further, volts is joules per coulomb. Amps is coulombs per second. Watts is joules per second, or in other words volts times amps. More current at the same voltage is definitely more watts.

I don't see the relevance to the problem at had. Might use the same in watt hours or whatever unit of measure you want to use but at 40A the load placed on the electrical grid at any point in time during the charging process is 8 times higher compared to 5A. It doesn't matter if the same amount of energy is transferred to the battery at the end of the charge if in one of the two scenarios the electrical system of the building cannot handle the load caused by the faster charging due to multiple chargers chargin at the same time.

Besides, in your footlong comparison from a charging point of view you'd just end up with two racers with half-charged batteries instead of one racer with a full pack.

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.

But in reality how many places have only one circuit breaker designated for the pits? I would hope they would be smart enough to have them broken into separate 20a branches so if something does happen they don't loose
the entire pit!!!

I would imagine there would always be a handful of circuits. But load balancing can be an issue. How do you guarantee that your 10 racers for the next main aren't all on the same breaker? Most track wiring was probably done before 40A charging was common, so they're probably set up for 10-20 people per breaker.

And in general a lot of indoor tracks weren't exactly built to be RC tracks to begin with, never mind people with crazy charging habits. I guess it depends on the country/area but here for example many are just generic warehouses or such on rent, it's not like you'll start rewiring electrical systems for that.

It still comes down to IF you feel safe at the track, regardless of power used and if the circuits will take the load, and I am not feeling lucky, especially inside during the winter months, so you can bet I will be asking at the track this very question on charge rates, come on spring/summer :nod:

Back to reality...

Define High current.