Rechargable AA’s. What’s better than NiMH?

cam.pngbattery2.gifYou have one of the digital still cameras that uses rechargeable AA batteries because, in a pinch, you can always go buy some Alkalne batteries at the store and take a few more pics. This works around the world. I know because I was stuck in Germany without a way to recharge the AA’s I had there.

So we bought a set of four Alkalines. And then another. And then another. Etc. Given the cost of those things in Germany, it wold have been a helluva lot smarter to just go and by a AA recharger with batteries the first time, but we didn’t think Alkalines would die so quick. Then the problem was that we’re in a small town nowhere near a decent electronics store- but the gas station is right down the street. Being able to use Alkaline batteries enabled me to document this international trip.

Trouble is, when you’re not using it, you put the camera on the shelf, or in the drawer. Then, when you see something that would make a great picture, you run to get the camera, turn it on and it says “Change the batteries.”

How do they die so darn fast when they’re not doing anything?

It turns out that all batteries loose their charge just sitting around. Rechargeable batteries are the worst.
Now, there’s been a small undercurrent of “new” NiMH batteries that tout longer shelf life. Eneloop is one brand, but there are a few others. To do some tests, I bought one such brand, and a new charger that came with some new traditional NiMH batteries. I also have a few sets of older rechargeable NiMH batteries. I charged them all, and let them sit in little plastic cases for months.

Then I put them in the camera and tried to take pictures. Let me tell you what happened… We have a selection of four batteries here.
Brand new Ultra batteries at 25oo mAh.
Also brand new, low discharge Ansmann 2100 mAh.
Older Powerex 2200 mAh (used a few dozen times).
And even older, but still decent set of GP 1800 mAh.


I charged them all in the same charger in February and then let them sit until the end of August. A full six months had passed from charging at they were all kept on the same shelf. A cool, dry environment. No direct sunlight. No heat. They were all stored in the same plastic battery holders- none were left in, or used in any electronic gear in the storage phase.

The results were pretty dramatic.
Everything was dead except the Ultra batteries.
With the Ultra batteries, I was able to take 143 photographs in a row with the flash on full burst before the camera shut down and said to change the batteries.

I was very surprised that the Ansmann Max-E batteries died. They tout similar storage capabilities as the Eneloop: “Because of the low self-discharge, charged maxE cells are ready to use for over 1 year. There are no speial chargers necessary. This new technology is the perfect energy source for all devices. These cells will be delivered precharged and are immediately ready for use.”
Um. yea. Whatever. They were dead in 6 months.

Despite the available power they demonstrated, I do not feel the Ultra were any super special batteries that everyone should go out and get. Rather, I feel that they were highly rated, and brand new batteries. They had the highest storage capacity by a good margin. This means that, as they self-deplete, there’s still going to be more power in there after six months. Well, aside from the Ansmann batteries which are supposed to self-deplete slower than noral NiMH batteries, which is what the Ultra batteries are.

I know for a fact that the Powerex batteries (of which I ave several sets) don’t store for very long, but I had never done a specific timed test of it. I didn’t really know what to expect or how long they might last. A more conclusive test would be a regressive test from the 6-month mark, charge and wait 5 months, 4 months, 3 months, etc. to see where the falloff is. But that’s 20 months or more.

There’s a review online of actual self-discharge (with graphed, test discharge rates) of both Eneloop and another unnamed NiMH battery. There’s a clear difference between the Eneloop and the traditional NiMH battery and their results differ greatly from what I experienced. His graphs show a slower and steady self-discharge of the Eneloop batteries versus a steep initial self-depletion of traditional NiMH batteries. Based on his chart, my Ansmann batteries should have been the ones that shot 100 pictures and the Ultra batteries should have been dead. But it was the reverse.

The Ansmann batteries have lowered my excitement when it comes to these low self-discharge NiMH batteries. I haven’t tried the actual Eneloop batteries, but then, those trade off actual mAh capacity for shelf-life. Because of the discharge characteristics of the batteries I have now, I usually have one set sitting in the charger and the second set in the camera. If the camera is dead, I just fill date.jpgit with batteries from the charger and I’m good to go. When I’m on a trip, there’s no long-term storage issues so mAh capacity is more important.

I’d love to have a rechargeable with the storage capacity of a dated battery, like Duracell or Energizer (I’ve had budget, cheapo, bulk Alkalines leak in electronic gear after just a few months- never again) but I don’t think that’s really possible. Lithium Ion cells, while shaped like AA batteries, are usually around 3.6volts. This presents numerous electronic challenges to design something that cold be used in standard AA devices. Also, recent numerous lithium ion battery fires and millions of recalls have demonstrated good reason why lithium ion batteries should not be made to resemble any other rechargeable battery- putting a lithium ion battery in the wrong charger could quickly lead to fire. idx.gif

Pro videographers will immediately recall the NP battery- a worldwide standard- that started as a NiCd battery, evolved into a NiMH battery that was slightly heavier but almost double the power, and then, with careful trepidation, IDX brought lithium ion NP batteries to the forefront of production in the 1990’s with sch a fervor that other battery companies that initially resisted this new technology just had to, and now do, embrace it. So it can be done.

Till we can get some lithium ion AAs. I’ll probably just get a few sets of 2900 mAh batteries and keep taking pictures.


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