Building an 18500/AA light?

So I have this 18500 FM body… Which obviously takes 18500, 14500, AA, NIMH and such. Well, this makes me want to build an 18500 P60 drop in! Great. Tons of 1S drivers out there. BUt what if we could do better? What if we built a light designed to run on an 18500 for best output and runtimes but could also handle AA/L91/NiMH, ya know, just in case? Well, thats even better. Except I don’t see ANY drivers rated for that type of voltage range. Do they even exist? I suppose they must since Jaxman, Four Sevens, Lumintop and others have AA lights that can run off of AA and 14500 cells. Most of those, like Jaxman and Lumintop, seem designed for AA and slip into direct drive for the higher output of the lithium ion battery. Four Sevens is different, my old Quark QPA displays almost identical outputs between those cell types. None seem to do what I’m looking for.

In a perfect world the driver would operate like this:

Li-ion: 2-3 mode levels without memory, no blinkies. Max drive around 2 amps, low mode about 1-5%.
AA/L91/NiMH: 2-3 modes, M-L-H without memory, no blinkies. High mode battery draw around 2 amps. Low mode 1% or less.

I’m sure there is nothing that fits those parameters perfectly but is there every a driver out there which functions in a similar manner with compatibility between two different battery voltages?

Yeh, Li usually means linear or buck. NiMH and alkie means boost. Best you’d find is boost/buck, like on a dual-fuel AA/14500 light.

Of course, you could gut the driver from one of those lights and use that, but you’d have to see if it’s 17mm to fit, or smaller and thus need an adapter. And you’d likely be ruining a perfectly good light to get the driver unless something else is busted.

Yah those a tricky because as was said, they just go into direct drive (limited by a weak FET) when on 3.7 volts. They conservatively drive the AA cells because of differences in chemistry between alkaline, nicad and nimh. If someone was so inclined, they could design something like a 2 channel driver that has a separate circuit for the lithium ion vs the 1.5 volt cells, but that would be difficult and expensive. Besides, the other AA/14500 lights out there are good as they are. Good idea though!

Convoy has a driver that works with NiMHs and 14500s(so theoretically with all 3,7V Li-Ions).

On paper 18500 sounds like it should be great. But I find you are usually so close to an 18650 size light, it just isn’t worth it. The hosts are always way bigger than any AA light. Plus you’d need inserts to use the AA in such a light.

Thanks! I wonder if thats the PWM driver from the T2? I also found this one, part number S024883 from KD. Its pretty close except the the strobe mode.

The red convoy T2 driver is the one with low PWM.

I’ve been messing with the red one quite a bit and have swapped the factory mcu for a attiny412. Works fine on 14500 as well. If you just want a 17mm clicky switch driver with modes you can specify I can put one together for you. Biggest down side is probably no LVP.

If you can tolerate mode memory then just get the blue convoy driver.

Ahh, I abhor mode memory. I can get used to anticipating a certain number of clicks but with MM its never 100% which mode you will start in for me. I wonder if the pencil trick could be used to eliminate it? Is this the red driver you speak of? Limited info on the page, does it play well with lithium ions? I could always use a protected 18500, I suppose. I’ll send you a PM to discuss your other proposal!

I can’t stand MM either. Pencil trick won’t work AFAIK. That link is the driver I’m talking about. I’ve been using one with a 14500 for a while without issue but IIRC Simon recommended against it. Maybe just because of no LVP I’m not sure.

I have a pic and current measurements at the LED from a modified driver at the end of the what did you mod thread.

Still looking for a good driver. The blue convoy isn’t too bad, but really trying to get away from memory. I basically will be running 18500 cell but desire AA as a backup/emergency option.

Has anybody experimented with the KD S025059 driver on li-ion? Its only rated for 3.3v so probably a no-go. Too bad, mode spacing is excellent on nimh.

Actually, found this thread from 2019. Looks like that 0.9-3.3v CF17 is a pretty decent driver. Might have found my solution.