What is the significance of ampere hour in the rating of the battery?

Question

how does the performance vary with ampere hour?

Answer 1

The ampere\hour rating is a measure of how much current the battery can deliver over the course of an hour. This rating is typically used on rechargeable batteries, and is typcially shown as mAh - milliAmperes per hour.

So what does it mean? Let say a battery has a rating of 500mAh. This means it can deliver 500 milliamperes of current for one hour. It also means it can deliver half that amount of current, 250milliampers, for TWO hours; or 100 ma for 5 hours. Get the idea?

So if one battery is rated 500mAh, and another 1000mAh, then the second one will run twice as long as the first. Sounds like an easy choice to make. But...

A 500mAh battery will charge at 100 mA for about 5 hours to be full charged. The 1000mAh battery will take twice as long. So you have to choose between run time and charge time when choosing your battery. With the new NiMh batteries, you should stick with the higher number. Even if you don't have the time to fully recharge, you'll get the full run time for the length of time you did charge it, and it will not suffer any damage by not being fully charged.

If you are using NiCd batteries (why?), then you need to FULLY CHARGE them before using them; and fully discharge them when you use them. This will provide the maximum life - ability to charge and discharge - than if you either partially discharge them or leave them around fully charged. NiMh batteries have no such problems. Try to stick to these whenever possible.

I purchased a few nightlights that have power-fail backup lights. They came with NiCD batteries. As an EE, I know that those NiCD's will go bad if just left on charge all the time. Should a power failure occure, those NiCd's may not work. I removed the NiCd's and replaced them with NiMh. I am confident they will work when needed. And they will provide lighting for a longer time, as the NiCD's were 600mAh, and the NiMh I put in are 1500mAh; nearly three times the capacity.

I did the same thing with my rechargeable electric razor. This way I don't have to let the razor fully discharge before I recharge it.

Answer 2

AH is the current the battery will deliver in 1 hour.

Answer 3

An ampere-hour is a unit of electric charge.

It's the amount of electric charge transferred by a steady current of one ampere for one hour.