Questions about AAA flashlights

Question 1: Why use 3xAAA? A single AA (2400mah) contains the same power as three AAA cells (3x800mah), takes up less space, and weighs less.
Simple math if you want to think about them in series instead: An AAA nimh cell is 800mah, and an AA cell is 2400mah. The voltage of the three AAAs in series is 4.5 while the single AA is 1.5.
4.5*800mah = 3.6 watt-hours
1.5*2400mah = 3.6 watt-hours

Yep, the voltage is different, but that's irrelevant since an LED can be made to run at any voltage desired.
Two AA cells take up about the same space as three AAAs and provide twice the power.

Question 2: Do 3xAAA flashlights run the batteries in series or in parallel? If they are parallel, I figure it shoudl be easy to mod such a flashlight to use a single AA or maybe even a C cell.

You are probably referring to lights with 3AAA's and a single Luxeon LED. Luxeons require more voltage than lesser LED's, so you either put in enough cells to get the voltage or you add an electronic boost circuit, which adds cost and complexity. Lots of cheap lights are made to be cheap, and they can do that with 3AAA's. These actually work reasonably well when the cells are fresh but output drops as the cells run down.

um.... 3xAAA in series is 4.5V(without load) 800mah.

most will use 3xaaa becuase it is cheaper to se a resistor then to find a driver for it.

that is why some of the made in china lights are found using 3xaaa.

but hey, now we have alot of good quality lights from china.

To make a white LED run on a 1.5 volt AA you need to put the current through a DC-DC converter to increase the voltage. As they are nowhere near 100% efficient you would in reality end up with much less than 3.6wh.

mercanucaribe said:

Yep, the voltage is different, but that's irrelevant since an LED can be made to run at any voltage desired.

Click to expand...

Actually, the acceptable voltage range is pretty limited for an LED, especially if it's to run with any efficiency.