Re: Recharging AA bateries

[Dave Plowman]

For a few quid I can buy a lead to connect my mobile phone to the 12v

> dash socket on my car and recharge its battery. I've got a small torch, > that can do the same. But the cheapest 12v battery charger for 4x AA , > is about £30. I think the phone lead just has a resistance in it to > bring the 12v down to whatever the phone needs. Could I make up a lead > like that to charge 4xAA's , and what resistance would I need ?

Re-chargables need a special circuit to charge them properly - something that gives constant current for Ni-Cads. This circuit will be built into your phone and torch, so a simple lead is all that's needed. But to charge batteries on their own needs a charger. However, 30 quid seems a bit steep. Have a look at Maplin for special offers - I think I saw one on a flier recently.

[David W.E. Roberts]

If you use 'AA' batteries then carry spares! They are dirt cheap, and you can buy them most places as well.

Also -

solar battery charger for under £12.

Also -

12V battery charge for under £25 including four batteries.

I am sure you can Google something even cheaper if you try :-)

Cheers Dave R

P.S. you probably pay the money for the charge controller (in the phone IIRC in your comparison) plus the box and contacts to hold the 4 AA batteries.

[Dave Plowman]

Not strictly true - a 1/10th rate will damage cells after they are fully charged.

[dave cunningham]

In message , John wrote

Here are a couple that come with a 12V lead...

or

HTH...

[Dave Plowman]

Good anything rarely is. But if you make heavy use of these sort of batteries, a good charger will soon repay itself in the longer battery life.

[The Natural Philosopher]

Th eart of charging small cells is nowhere as danaced as in teh toy plane and car department.

Visit your local model shop.

Ther are chargers upo to £600 that will charge all sorts of conbiantion sof cells, simultaneiusly.

A decent FAST charger for running off 12V should be less than £30.

[Matt]

Got this one and it works very well.

Jo

[John Laird]

Oh, I'm aware of that. (And I'm presuming that weird word in the middle was supposed to be "advanced".) Is it fair to say that rapid charge capabilities are probably of greater importance than charge cycles ?

Your £600 charger might be a little ott for boosting 4xAA cells however ;-) It's probably more the thing you need when the flight-line director tells you you have 20mins +/- 2 to get your 72-cell(*) V-bomber ready for take-off.

(*) Or whatever. Didn't see many electric behemoths up at Cosford this year.

[Stuart]

Try

Stuart

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Remove YOURPANTS before E-mailing Me

[usenet]

The difficulty is working out from adverts etc. which chargers really are genuinely 'intelligent' and use the correct delta/V detection circuitry to stop charging when the battery is fully charged.

I believe you can get chargers that work this way for around the £20 to £30 mark now, the chips to make such a charger are certainly available pretty cheaply so the cost of the hardware should be hardly any more than for an 'unintelligent' charger.

Does anyone know of any universal chargers (i.e. for AAA, AA, C and D cells) with delta/V detection at reasonable prices?

[The Natural Philosopher]

Not 'universal' in teh sense that they come with battery boxes etc.

But any decent model electric charger will be adjustable in current and have full 'delta peak' detection and be able to charge Nicads at least to within an inch of their life ain about 12 minutes from flat. NiMh is more tricky - the allowable charge current is much less - at best half an hour - and the delta peak is very small - less than 100mV - so you do need to be careful.

I have solved the unuiversaility aspect by replacing in most cases the battery box, and use standard model packs in the radios etc.

Sadly it doesn't wok for TV remotes etc, but then the batteries wear ouit so seldom that I don't bother with rechargeables.

[John]

Thanks to all who responded. The 7dayshop seems to be the best value. I'll try them.

Cheers John