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Homemade "power runner" battery pack for camera mp3 player cordless drill??

I'd love any info on making a homemade device like the one here

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Power Runner Universal Battery pack

How about this...

10 NimH AAs to make a 12 volt pack Charged by a Multi-Current Universal Smart Charger found here
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I need the charger to be compatable with 110-240 volts for overseas travel.

But how do I regulate the output voltage going to my different devices which need different voltages? I was thinking of hooking the pack up to a cigarrett lighter and use a multivoltage cigarette lighter adapter like the one found here

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Would this be inefficient?? Or is there a simpler way..like an inline switch that changes the voltage?

When you have a 12 volt battery pack and power devices that run below 6 volts are you sacrificing efficiency?

Thanks Jay

Reply to
jay_beveridge
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good idea

Cordless drills usually use sub-c cells, I'd go with those - or a ready made 12v drill pack.

voltage regulator.

cars run ITRO 14.4v with engine on. I forget what V NiCds need to charge, but it might be higher than this.

yep

yep.

There is a better way, which is to run your 6v devices off half of the batteries, then off the other half. The (trivial) downside is you need to charge them as 2 packs of 6v, ie your charger to battery connection will have 3 wires not 2. This way you'll get twice as long run times on

6v loads, and ditto with
Reply to
meow2222

They need a constant current source not a constant voltage. There might not be enough headroom to make a decent constant current source if you only have

14.4V
Reply to
CWatters

Doesnt necessarily have to be constant, as long as its limited. Of course they cant be charged from a V source like lead acids.

If the NiCds needed 13v minimum, one could probably work with that, using eg a low dropout current limiting regulator. But I dont know what V is needed.

There is one workaround if theres not enough headroom: charge the pack as 2x 6v packs. This means breaking the connection halfway along the battery chain - eg with a piece of card - and current limiting the charge for each 6v section.

NT

Reply to
meow2222

Yes that would be the best way to go. You can buy chargers for that really cheap.

Reply to
CWatters

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