strat1080 said:
So I guess my question is. Would the incand bulb benfit from having less voltage initially and more consistent voltage overall from the flatter running Nimh batteries? Would the Nimh batteries actually have a flatter output in incand. or would it be similar to alkalines in these lower drain incand flashlights? Simply put, I'm trying to figure out if it would be worse or better on the light by using Nimhs.
The ni-mh would provide a much flatter discharge curve. They do lack the initial punch that alkalines give in the first couple minutes, but over the life of the charge, they'll give off a lot more light (area under curve) than alkalines.
Ni-mh would give a flatter discharge even under a stock minimag's current. About the onlything where an alkaline would beat a nimh is a clock
I believe all alkaline rated capacities are @ 0.025amp (completely useless).
Don't think bulb life is really affected by much. If you look at the bulb ratings, they're actually right in-line with the equivelent ni-mh voltages (i.e. 2 cell 2.5V, 3 cell 3.7V, 4 cell 4.8V, 5 cell 6.0V, and 6 cell 7.2V). Either way it's not really a concern. But when you're overdriving the bulbs (see my post above) it's totally different.
Two AA batteries running at about 1.2v ea I think would be better for a bulb designed to run at about 2.3-2.4v rather than batteries that start out at 1.6v+ and then fade down to about .7v throughout their life. What say you?
To be honest, I don't think they'll be much different. I can't recall the relationship between voltage and bulb life (search for the formulas), but IIRC it's exponential.
Study a running voltage plot, you'll probably find that for the most part, an alkaline spends more time under 1.25V (nimh running voltage under a low drain bulb) than above it. If the relationship does remain exponential, then I'm sure it'll average out to be about the same. To find the exact difference, you'll have to get the plots, the formulas, and do a little curve area estimation or integration.
But like I said before, any difference is probably negligible provided you're not overdriving the bulb with the nimh.
I've also seen some manufacturers recommend not using rechargables and I'm trying to understand why. I personally think the bulb would actually benefit from not having the initial overdrive from alkalines and the more stabile current of Nimhs.
The only reason I can think of is that the manufactures (especially a mass market flashlight company like Mag) wants you to see the initial brightness on a fresh pack of alkalines and go "whoa!".
Underdriving a bulb will ALWAYS give you more lift. This is why DRL high beams driven at 6.0V (depends on the car, my Nissan used 6V) takes a lifetime to burnout even though most high beams are only rated for 200 - 300 hours at the full 14.4V.