My Batteries, mAh Ratings
How to Read the Ratings on Your Rechargeable Batteries
You’re probably going to recharge a battery today.
Chances are it will be some kind of lithium-ion cellphone battery or, if you followed our advice about getting some rechargeable AAs or AAAs, a few nickel-metal hydride batteries. If you’re charging your or batteries over and over again, you may have the wrong mAh rating for your device.
Shopping for NiMh batteries may mean studying some alphabet soup on the labels: the A-A, the N-I-M-H and then a mAh rating. (That’s milliAmpere hours.) Which mAh rating should you choose? Should you go with 800 mAh or 2,500 mAh? It’s all enough to make you go “Mah!”
That mAh rating could be the key to getting the most out of your NiMH batteries after charging. Let’s break it down.
Think of the mAh rating as the battery’s capacity to store electricity. If the battery were a bus, the mAh rating would be the number of seats. If the battery were a meal, the mAh rating would be the number of calories. If the battery were a cow—well, you get the idea.
So if you find your digital camera totally devours your NiMH batteries, their mAh rating may be too low. Check your device’s user manual or the battery housing for any indication of how many milliAmperes it uses. If you find one, get NiMH batteries with a mAh rating at the same or better.
However, most devices have no indication of how many milliAmperes they need, leaving you guesstimating. Are you trying to power a digital camera with zoom motors and an LED screen instead of an old-school viewfinder? Or a stuffed pony your 5-year-old constantly squeezes to hear that loud giggle? If you’re powering something you use constantly, get the highest mAh rating you can. You’ll find your batteries have longer run times.
If price is an issue, you can back down to lower mAh-rated NiMH batteries for devices needing a moderate dose of power: TV remotes, flashlights and that same stuffed pony when the loud giggle gets annoying to your 5-year-old, too.
But what about the analog wall clock hanging in your office? The kitchen flashlight you only use when something falls behind the fridge? The under-usedthat your best man bought you? Wouldn’t putting the highest mAh-rated NiMH batteries in them ensure you’d never have to buy batteries for those devices again?
A 2700 mAh NiMH battery will self-discharge faster than the analog wall clock will drain it. For those devices that rarely use a low level of current, choose another chemistry with a low mAh rating: maybe some inexpensive carbon zinc or nickel cadmium batteries. You’ll get more life out of them than your typical alkaline batteries, and you won’t have to recharge them more often than you use them.