Wow. It was nice of you for taking the time to put this together. I need to keep reading, but so far it is very informative!!
Many Thanks!
Yes thanks again to you MDOCOD for writing this article. Its an invaluable reference for me.:thanks: I refer to this thread as my Incandescent flashlight bible.
. I also read this thread often.
It's sticky status is well deserved.:thumbsup:
I already have the P91 with 2 X IMR16340. I just wanted to increase runtime but not at the expense of bulb life.
Will the bulb last longer with 2 X 16340 or 2 X 18500?
It will last (runtime) at least three times longer with 18500 (1500mah) over 16340(550). Lico cells have 1/3 more capacity than IMR, and the 18500 about double in Size and capacity compared to a 16340 LiCo cell. The IMR will run at a lower voltage faster than large LiCo cells
The bulb life will not be much different. If you like what you see with 2x16340, you just see that for longer per charge. Since the voltage is slightly higher with 2x18500 over the run compared to 16340, the bulb life will be just slightly less. but the difference is so minor its hard to say.
lovecpf
Basically if I remember what MDOCOD taught me, the Voltage will sag less on the larger 18500 LiCo cells than with the two little IMR 16340..so it will stay brighter, for longer.... You also get alot more runtime with just a little less bulb life. However youd have to recharge 3 times as often to save that little bit of bulb life.
Its an awesome setup only because your overdriving the bulb.:devil: However that 400+ lumen overdrive means alot less bulb life than 25 hours at 120 Lumens on 3volt CR123 disposable primary SF cells. Ironic isn't it? If you want max bulb life, dont use any 2 rechargeable Lithium ion cells at 8.2 volts. Two 4.2 volt Rechargeable cells run at a higher voltage than three 3volt primary disposable CR123 SF cells.
Its a trade I would, and have, made.
You get so much more runtime that any additional small loss of bulb life would be well worth it to me.
I would guess you can recharge the 18500s about 3 dozen times before killing the P91.
Maybe 20 hours bulb life instead of 25? By the time the bulb is ready to burn out it will be very black anyway, with any batteries. Thats the one reason I don't like Xenon bulbs as much as halogen. They blacken before the bulb filament gives out..I always replace P90 and P91s before they die on their own anyway,
these are just guesstimates, but I can't be that far off.
The shorter answer is, more bulb life, slightly more, with two little IMR because their voltage sags quickly under that huge load. But if your going to overdrive the bulb, do it with two 18500 Black lico AW cells.:devil: The longest bulb life would be with 3 Primary surefire cells, but that'd be no fun at all. You've already lost 90% of the bulb life your sacrificing anyway (maybe 15 instead of 25 hours) by switching to 2 Rechargeables, so go all the way I say. It wont be physically that much bigger but it will run much longer. Same size as a 9P again
:welcome:
