Amps vs. C - What's the Dif?

[recDNA]

When looking up maximum discharge rates for various types of batteries I see them sometimes listed in amps and sometimes in C. I thought C was amps/sec but then I noticed that one dealer listed a maximum rate at 2C or 1.5 amps. I don't get it.

Thanks!

 

[tolkaze]

isn't C the capacity in Amp Hours? for instance if the battery is 750mah then 2C would be 1.5 amps

 

[recDNA]

isn't C the capacity in Amp Hours? for instance if the battery is 750mah then 2C would be 1.5 amps

So I need to divide amps by mah/1000 to get C?

 

[Qoose]

Correct. It's the Amp Hours [Ah] * C = Max Current [A]. We just like to work in milliamps.

 

[Mr Happy]

It doesn't make any difference whether it is milliamps or amps. C is the 1 hour charge/discharge rate. 2C is the half-hour rate, C/2 is the 2 hour rate, C/10 is the 10 hour rate, etc...

 

[csa]

Most batteries are rated at C/5 or so, which means that when you discharge them at 1C, you get less power out of them.

 

[McAllan]

Amp (A) is an absolute measurement of current.

C (I'm sorry I can't remember what it stands for - may just stand for specified capacity) is relative to the specific cell.

If you have a cell rated at 2 Ah (=2000 mAh as milli just means 1000 as in milliliter) then 1 C is 1 hour discharge rate - here 2 Amp.

It is however true that you most likely won't get full 2 Ah out of a 2 Ah cell at 1 C because most cells are rated at 1/5 C. In case of a 2 Ah cell 1/5 C is 0.4 A or 400 mA whichever you prefer.