What does the "C" mean?

[Gsquared08]

1c, 2c charge rates I figure has something to do with the output charge rate but what does the "C" actually stand for?

[George1234]

As far as charging goes, C rate is how many amps you can charge at. First note that 1C is normally the max. recommended. A 2200mah battery at 1C can charge at 2.2 amps. The same battery at 2C would charge at 4.4 amps. A 3000 mah battery at 1C would charge at 3 amps. The same battery at 2C would charge at 6 amps and so on if you get the drift.The charge rate should be selectable on your charger.
Just as an aside, the C rating takes a twist with battery "power". That same 2200 mah battery, if it has a 20C discharge rating is capable of safely supplying a max of 44 amps to the motor. If it has a 25C rating it can safely supply 55 amps to the motor.
The key word here though is "safely". Under short circuit or stalled conditions, the battery will provide enough current to destroy the battery. On the good side, this is where the esc steps in, and shuts down due to overcurrent.

George

[Gsquared08]

Perfect!!! Great explanation!!!

Thanks so much,

G2

[BarracudaHockey]

Pack size * C rating / 1000 gives you the amps that it can discharge continiously. There's also sometimes a burst rating where it can handle that for a few seconds at a time.

So a 2200mah pack * 25C = 55000 ma output
55000 / 1000 = 55 amps

[Steel Butcher]

"C" stands for the capacity of the pack. For example, a typical 3S 2100 t-rex pack can provide 2100ma (=2.1 amps) for one hour. (you wouldn't want to drain it that low). So you could say, for this pack 1C = 2.1amps.

This C rating is useful for determining how quickly you can drain and recharge the pack, which is what the manufacturer will specify.

A 450 heli draws much more than 2.1 amps so your flight will last much less than an hour, say 6-7 minutes. The larger the amp draw the quicker you drain the pack. There is also a limit as to how large that draw can be, such as the 20C example above.

How quickly you can recharge that battery is also specified in C. A 1C recharge in this example would be 2.1 amps. So, in theory, a 1C recharge would take one hour, since you are replacing 2100MA in one hour.

Manufacturers could have ignored this "C" rating and given ratings based on amperage, but that would make it hard to compare packs across different mah's. Now it's easy to know that certain makes are 15C, 20C, etc.

[Migs]

Here is a good answer:

http://www.rcgroups.com/forums/showthread.php?t=209187

Migs