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I want to extend the use of a camera. The camera currently uses a special li-ion 3.7V 1000 mAh battery. I could grab a couple of those batteries, wire them up in parallel, and that'd work just fine. But if I didn't want to use those special batteries, would there be any problem using standard batteries? For example, could I wire up three AA 1.2V 2400mAh bats in serial to end up with a 3.6V 2400 mAh battery?

Now my real question: Is the voltage difference (3.6V versus 3.7V) a problem, or is it close enough?

Thanks.

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Li-ion batteries range from about 4.3V - 3.3V as they discharge. 3xNiMH batteries would range from about 4.2V - 3V as they discharge. Too low of a voltage is not a problem, the camera already will have circuits to not turn on if the battery drops too low. All it means is you might not get the full use out of the NiMH batteries as compared to the Li-Ion, but there wont be any harm to anything.

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  • \$\begingroup\$ I've always seen Li-Ion batteries specced as 4.2-3.0v... I guess manufacturers vary. \$\endgroup\$ – Connor Wolf Jul 11 '10 at 10:04
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That will work just fine, but you should measure the voltage of your 1.2 V cells to be sure. As they discharge, their voltage will drop.

I suspect that your camera has a 3.3 V low-dropout regulator; I bet you won't get into trouble until very close to 3.3 V. Even if the voltage sags, I suspect that the worst that will happen is that the camera will turn off sooner than you want.

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Lithium batteries are occasionally marked 3.6 or 3.7 volts. More often 3.7 because it looks better. But it's a nominal marking and, as said, the real voltage goes from 4.2 (cutoff to prevent overcharge damage) to somewhere around 3 (cutoff to prevent deep discharge damage). So nickel (or alkaline) and lithium batteries will spend a lot of time in the same range, as it were.

It should just work, presuming you take care of charging correctly. There may be a difference in how the battery (and the device!) behaves once the batteries are getting close to empty and how they age. I suppose this is a digital camera that will write to flash memory. That takes a certain voltage at some current. If the battery is too weak and dips when its loaded, the write might get interrupted with undefined results. But it all depends.

If the device and its functioning is very important (you're taking the photo of a lifetime...) I wouldn't risk adding random variables like batteries it wasn't designed for. If it's for random use and will work better for you with the new batteries, I'd absolutely go for it.

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    \$\begingroup\$ "3.6 or 3.7 volts, more often 3.7 because it looks better": A nice source with detailed explanations about this nominal voltage difference is here. \$\endgroup\$ – tanius Feb 9 '16 at 13:39

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