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Old 03-11-10, 02:11 PM   #1
mcahill844
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Using AA Batteries to Power Magicshine?

I've read some posts about alternate batteries for the magicshine. They inolved using lithium batteries and a protection circuit.

Could one simply power magicshine with six AA batteries in series? I realize that you would only get approx 2400 mah instead of the 4000 mah that the magicshine battery produces. But there are also some advantages:

- I could take advantage of my advanced AA battery charger (maha 9000)
- Alternate batteries and battery replacement is cheaper (6 x $2.50) vs $40 for magicshine.

Would the indicator light on the back off the light head still work?
Would I need a protection circuit?
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Old 03-11-10, 07:02 PM   #2
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I imagine the indicator just goes by voltage. It'd go off at a different time.

Sure, as long as the voltage is in range, I'm sure it'd work fine. I have a friend who is using two MagicShine lightheads running off his 48 volt eBike pack using a couple of buck voltage converters.

The protection circuit on the LiIon is simply in case the wires fray and short out - if you have never seen what a LiIon does when shorted without protection circuits, check YouTube. It would be "exciting" to have that happen on your bike while riding.

NiMH doesn't like getting shorted either, but the effects would generally be limited to getting really damn hot and probably melting the plastic it's in, not exploding, catching fire or jetting around on a rocket of steam.
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Old 03-12-10, 10:21 PM   #3
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It's probably worthy of an experiment. I can think of some things to maybe consider.
-Yes, you'd get half the runtime.
-6 AA NiMHs is maybe 7.5v. It's not clear to me if the lighthead itself has any minimum voltage shutoff to protect the powerpack from overdischarge (or if it's in the battery pack circuit). If so, it's probably nearly 7v, IIRC. If your NiMH pack has some resistance between each cell, and they start to sag near 1volt each, you might be out of light, or get a stepdown.
-The NiMH pack - I don't know of any good holders with low resistance and easy changeout. The resistance of the springs in common holders is a big problem.
-You could try a 6P2S pack (2 parallel stacks of 6 series) for more current. Bigger and heavier than the LiIon, tho.
-Maybe consider 7 in series, but the max voltage (maybe about 9.8v fresh off the charger) might be too high for the MS head regulator board (maybe designed with 8.4v max in mind).
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