Alkaline and Nimh questions

[Nitroz]

I have a few questions about the differences and effect when using these in flashlights.
I know that Alks are 1.5v for aaa,aa,c, and D's, with increases in the Mah for the larger cells. I also understand that the NimH are 1.2v but have a higher Mah. So my question is, would it be safe to use the NimH with the highest Mah in a DD mag? If not, why?
Thanks,
Russell

 

[brickbat]

When you ask if it's safe, I'm assuming your concern is that the higher mAh cells will provide excessive current to the bulb, possibly shortening its life? In that sense, don't worry. The bulb will be perfectly happy regardless of the cell's mAh capacity.

Also, as you compare Alkaline to NiMH, don't assume that, just because the NiMH in only 1.2V, your light won't be as bright. In fact, over most of their discharge life, the NiMH cells will provide higher voltage to the bulb. (Alkaline cells drop off quickly, particularly when heavily loaded, and at cold temperatures.)

So, in short, the NiMH's should be fine. The only drawback I see is their self discharge is substantially higher than an alkaline cell.

 

[Lynx_Arc]

actually alkalines have higher mah.. BUT... that is only under lighter current drains. Nimh have less internal resistance and also are less prone to sag when under a heavy load so in those cases nimh has higher *useful* mah. It should be safe to use nimh in all but direct drive luxeon flashlights. In some cases the Vf (forward voltage) of the luxeon is lower than the starting voltage of the batteries and since nimh dont sag much voltagewise you can actually overdrive the LED so hard it can fry.

 

[Nitroz]

Thanks guys.