Help: Two Flashlights, Two Bulbs, Opposite Shelf Lives

[hoffner5]

Okay, perhaps someone in the know can explain the phenomenom I'm experiencing.

I have two flashlights that sit in my desk drawer for long periods without being used:
a) 2D Maglite (FM 6AA NiMh) with ROP
b) 1D Maglite (Modamag 3AA NiMh) with LED

Both use the same batteries. Flashlight B has not needed its batteries charged... ever. Going on a year. But I use it maybe 5 minutes a month. Beam looks just as good as when I fully charged the batteries.

Flashlight A has needed its batteries charged, well, at least every month. And I use this flashlight not at all (well, I hit the switch every week or two just to check if the batteries are still charged).

So, why is my 6AA ROP self-draining, but not my 3AA LED?

 

[Valolammas]

Different NiMH cells can have different rates of self discharge. Even different cells by the same manufacturer and from the same batch can have very different performance. What kind of cells are you using, by the way?

In the ROP, all it takes is one or two bad cells that lose their charge quickly and the other cells just can't supply the bulb with enough juice to blaze as it should. Incans don't perform very well when they are underdriven. On the other hand, if your LED light has any kind of regulation, that might help it fire up at almost full brightness even if the cells have self discharged quite a bit.

Don't know if this was of any help... You might want to check your cells individually, especially the ones in the ROP.

 

[mdocod]

because you probably made your ROP from energizer 2500s. (did I guess correctly?!?!!?)

 

[hoffner5]

because you probably made your ROP from energizer 2500s. (did I guess correctly?!?!!?)

Yes, I did. Both lights use these batteries. The reviews for these batteries have all been good. What don't I know that you do?

 

[tebore]

Yes, I did. Both lights use these batteries. The reviews for these batteries have all been good. What don't I know that you do?

After a few high amp runs the 2500s start to break down and start to develope high self discharge. Your LED I assume isn't pulling 3 AMPs so the batteries haven't been in high stress applications causing accelerated degradation.

 

[mdocod]

sorry forgot to check back on on this one...

As tebore already noted, the energizer 2500s have a lousy track record of insane self-drain rates. I have a set sitting on my desk that I haven't figured out a use for anymore because they go from full to 0.9V in about 10 days of resting.

 

[tsia]

Go get the Sanyo Eneloops these should last better, but the main diff is the current needed to drive the circuit and self discharge as mentioned. My Nimh would self discharge even if left in a desk without putting in a light.