Quote:
Originally Posted by budfish
So what your saying is the " c rating" is dependent on the " mah". Well I thought it was the speed it discharges it self and the mah is the amount of power the cells can hold. But seeing as your a chemistry teacher who where's specs I'll have to take your word for it
buds
|
Well you are right, it is the discharge rate, but in this case C stands for capacity. A 20C pack can discharge 20 times its capacity in 1 hour (more simply completely discharge itself in 1/20th of an hour or 3 minutes). That means however that the current it delivers depends on the mAh of the pack too.
A 20C 3000mAh pack can deliver 3A for 3mins (effective rate 60A)
A 20C 6000mAh pack can deliver 6A for those same 3mins ie 120A.
A 3000mAh 40C pack could discharge itself in 1/40th of an hour or 1.5mins. That too would allow an effective current of 120A
These are continuous discharge figures, and since as you pointed out a race is only 6mins long (and you don't use the whole pack in a race) it shouldn't really matter. However, the burst discharge rate is closely related to the continuous discharge rate - normally around double. Since 4wd cars with 5.5-6.5t motors can pull up to 200A under hard acceleration the 20C 3000mAh pack can only put 120A and is not going to accelerate that well. The 20 6000 pack can manage up to 240A and is going to shoot off the line!