Saturday, 1 September 2012

Rechargeable batteries

One of the problems with rechargeable batteries is that they never seem to last as long as the advertising claims. But are they still worth buying?

I use rechargeable batteries in a few different gadgets. The manufacturers usually say that their batteries can be recharged hundreds or even thousands of times. But I've found that I usually have to discard them after much less use than that.

The problems and the reasons behind them

Some of the batteries I have will no longer charge to their full capacity. Apparently, this is part of an ageing process that can't usually be reversed. So the affected batteries are charged, but they only last for a very short time.

The other problem is with batteries that lose their charge over time, even when they're not being used. Most rechargeable batteries do this to some extent, with many needing to be recharged after a few months. However, I have some batteries that lose their charge completely over a period of one week. If I can use them on the day I charge them, there's no problem. Apparently this is an ageing process too, and is perhaps why these particular batteries were less costly than other makes.

The solutions

All the batteries I'm using are the (fairly) modern NiMH types. There's a new kid on the block though: Nickel Zinc batteries. They seem to have a number of advantages, including a slightly higher voltage, which enables them to work in some gadgets that don't normally play nicely with rechargeable batteries. However, Nickel Zinc batteries need a special charger - you can't use a normal one.

It is possible to "recondition" NiMH batteries by running them flat (so there's no charge) before recharging them. Although it also seems that if you run them too hard, too often, then you can also run into problems. Chargers that recondition automatically tend to be quite pricey compared to the standard equivalents, so I'm not sure if it would be cheaper and more efficient to just put the batteries in an old torch (flashlight) and leave it switched on until the light goes dim.

Hybrid batteries are also useful to know about. They're a special kind of NiMH battery that keep their charge for longer. I find these are ideal for my camera, which can get no use at all for a few months, but then be called into action for an impromptu day out or event. Hybrids are also supplied ready to use, straight from the pack, which can be useful in some situations. The two main brands I've come across are Uniross Hybrio and Sanyo Eneloop. You might not think of Sanyo as a big battery producer, but for many years they have made "own brand" rechargeables for other people. 

The Conclusions

Going back to the point I mentioned at the start, a battery that can apparently be charged "up to" 500 times may not achieve 500 charges in your home. It's marketing-speak. Take it with a pinch of salt.

As for disposable batteries, they can be recycled in the UK, and there are collection points at most major supermarkets. But it still seems to be far more efficient and cost-effective in the long run to use rechargeables.

Overall, rechargeables are great. They save money, save the environment, and most of the time they work very well. Sure, there are a few niggles, but I'd rather have rechargeable than disposable batteries any day.

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