On the subject of rechargeable batteries
I have a fairly sizable collection of rechargeable batteries. My need for them started when I got my first wireless mouse and was chewing through batteries at an alarming rate. Shortly after that, one of our digital cameras required AA batteries, and so I picked up even more batteries for that.
Now, after using rechargeable batteries for about two years, I have about 24 batteries either charging or in use at any given time. My digital camera, mouse, remote controls, Xbox controllers, and a few other devices all use them. And so far I’ve been pretty happy with how they’ve held up, and how much money they’ve saved me from needing to buy new batteries.
However, recently - I’ve begun to start tossing batteries as they aren’t holding a charge. Each time I find a “bad” battery I mark it with a black marker and try to bring it back to life one-last-time before ditching it. I wish I could somehow keep track of how many times I’ve charged a battery, but that doesn’t seem very possible. I think the next time I buy a new set, I’m going to write the date I bought them on the battery itself somehow so that I can keep track of how long they are lasting.
Does anyone know, for sure, how long these are supposed to last?
The type of battery that I buy, because they seem to give me the best mileage, is the Energizer 2500 mAh Nickel-metal Hydride AA batteries. So far I’ve not been able to find a battery that does a much better job or lasts as long. But, I’m open to suggestions, stories, tips and tricks, for getting better batteries or just making mine last a bit longer.
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There are no hard and fast rules on this, but there are two main things to look out for:
1. The age of the battery. Even if you never use it, it deteriorates.
2. The number of discharge/recharge cycles. I’ve read that NiMh batteries in general (AA’s, Laptop betteries, etc), are rated for ~400 discharge/recharge cycles. I have seen that number in multiple sources.
There are also a lot of secondary factors: Storage temperature of the batteries, temperature during operation, charging method, depth of the recharge, etc.
Energizer has some datasheets on their batteries, but they don’t really seem to have a good specification on this.
http://data.energizer.com/PDFs/nh15-2500.pdf
http://data.energizer.com/PDFs/nickelmetalhydride_appman.pdf
Myron A. Semack on January 8th, 2008 10:35 am
Myron: Thanks for the information. Obviously it is nearly impossible to keep track of all of those factors. I guess what I’m trying to get to is, “how do you know when a battery is truly dead”.
My gut feeling is that I haven’t approached the 400 recharges mark with any of these batteries, though some of them are starting to die.
Chris has the same batteries with a different, much faster, charger. Is this worse on the batteries? Better? In my experience with batteries (not much) I thought a slower charging cycle is actually better for the longevity of the battery.
Thanks for chiming in!
Colin Devroe on January 8th, 2008 10:40 am
It’s not quite as simple as “slower is better” (although that may be true). There’s a whole set of equations for temperature, and how the input current is moderated as the battery fills up. The second PDF I linked to covers some of it. Read pages 16-24.
Regarding the ~400 number: That translates to (roughly) one recharge per day for a little over a year. If you’re recharging them less often, you would make it longer than that. If you recharge them once a week, then you would be good for ~7.6 years. Of course, by that point, the batteries would probably be failing just because of their age.
Myron A. Semack on January 8th, 2008 1:09 pm
The energizer 2500 are pretty bad batteries. Try Sanyo eneloops, they don’t discharge on their own like normal rechargables do so they last much much longer.
deadsunrise on January 11th, 2008 4:10 am