# What's the C rating for NiMH batteries? [duplicate]

On most hobby Li-ion packs there is a prominently displayed C rating (typically 20 - 35), which tells you how many amps you can draw from it, in a multiple of the capacity.

I have never seen a C rating on a NiMH pack. Neither do you normally see how many amps you can draw from the battery.

What is a typical C rating for a NiMH battery?

Note: I am looking for an estimate, so if it's a range, go ahead and put that. I do not have a particular battery in mind.

EDIT:

I can see that I was misunderstood already by EM Fields. Let me try to clarify. The C rating refers to a constant with units of 1/hours which gives the peak amp draw in terms of the capacity, like this: Capacity [Ah] x C rating [1/h] = Max draw [A]

• There is no "typical C rating for a NiMH battery". Your question(s) are based on faulty assumptions. It is not even clear that you even are using the proper definition for "C rating". Commented Jul 20, 2016 at 5:00
• Commented Jul 20, 2016 at 8:22

Capacity of a battery, or a cell, is given in ampere-hours and specifies how long current, at a specified rate, can be taken from a battery before the battery's terminal voltage will decay to a specified value.

Check this out.

• I think the asker was looking for a number, not a definition. Commented Jul 20, 2016 at 1:23
• I chose to teach him how to fish, since without a specific battery in mind, his question was unanswerable. Commented Jul 20, 2016 at 1:28
• This is not what I was looking for at all. Capacity in Ah x C rating in 1/h = maximum continuous current in amps. I want to know what that C rating typically is.
– dpdt
Commented Jul 20, 2016 at 1:31
• @dpdt: Maybe I'm missing something, but if you have the formula in hand what's stopping you from getting the answer all by yourself? Commented Jul 20, 2016 at 2:14
• The fact that there are two unknowns in the formula. Commented Jul 20, 2016 at 2:20

The "C" rating specifies the maximum safe continuous discharge rate of a pack. If you see 10C on your battery, it means it can be discharged at 10 times that pack's capacity.

This applies to all batteries. There is no difference between Li-ion and NiMH (or any other chemistry, for that matter). If you are not seeing the capacity or "C" factor for batteries, then you are shopping in places where the vendor isn't giving you the full specifications.

Avoid buying from people who don't know what they are talking about, or who fail to reveal all the important specs, whether knowingly or ignorantly.