Good light for 18650 LifePo4 use?

Got a few A123 brand LifePo4 18650s. Trying to think what the hell to do with them! :~

Thought about keeping my XinTD C8 in the car with these cells… but voltage cut-off of that driver is a deal breaker. (Guess IMR would be better.)

There’s gotta be something I can do with these lifepo4 buggers. Any of you guys run these cells at all? What do you use them in?

dual cell lights would probably be good to use them in. that is, if they dont have a fairly high cut off voltage

I would think you could run 2 of them in lights which run on 1 or 2 18650's (so your 2 LifePo4's would be within voltage range between 1 & 2 Li-Ions).


Hmmmm that’s a thought. Too bad SRK and Armytek Barracuda are currently my only multi18650 lights. Guess I might need to look around for a new one. :slight_smile:

Want something fairly throwy but not too expensive. Would live in the car for outdoor spot/search use (or club if need be, god forbid). Already have smaller emergency / work lights for the car. Let’s say in the $20 - $50 range. Any suggestions?

What’s that 2x18650 light that looks like a stretched slightly bigger C8? Can’t recall if it was single/dual cell or purely dual…

This sounds like what you’re looking for. $10 if still going.

The tube fits the DST and holds 26650’s too.

EDIT: Forgot link. I don’t know if this runs on one cell. I can try tonight.

That t13 will run on one or two cells, would work good with lifepo I'd imagine

I was going to suggest a Small Sun T13, but assumed it wouldn't run on a single cell.


Out of budget, but if you like the Barracuda… the Predator has a battery type selection specifically for lifepo4….

Which comment? Your link just takes me to top of pg2. Is it #50 on that page? If so, I noticed this on meritline: Voltage Input: 7.2~9 V, 9 V max. 7.2 min is too high. If that is accurate? :~

Good point. Maybe I could buy another one and leave it alone (XML). That XRE is too much of a pencil thrower for this intended use. Price, voltage range, and size seem to fit criteria.

What type of single 18650 did you run it on and how low did you take it?

LOVE my Barracuda. Normally too spendy for me, but I got it on sale from IS at a great price. Predators are very nice too… Too nice to leave in my car. Good to know they can run these cells though.

I have exactly the same (unprotected) cells from A123 and other brands and also protected ones from Soshine. I use those cells in a Fenix PD32 UE and only the A123s are able to hold the voltage at burst level (740 lm), on other cells the low voltage protection kicks in. Other lights i use with LiFePO4 (i don’t own 18650 LiIONs):
Ultrafire C303, SK98, 270-T60, …
Citycat YEE-Lic XM-L T4-7C
Basically all my 18650 lights work very well with them, especially the A123s, because they hold voltage better on higher loads.
Other brands are rated at 3.2 volts, A123s are rated at 3.3 volts under load.

Sorry, link should have taken you directly to Post 62. Yeah, it’s advertized as a 2 cell only light, but I’ll try 1 cell in it tonight to see if it works.

Link worked for me. I guess Haterade has a different "posts per page" setting from us. Seems we need to remember to state the post / comment # when linking to a specific post (I forget to do this too).


Thanks for your input UliBar. Sounds like all those you listed do not have low voltage cut off.

Let me know 4wheeler. If it does OK on a single cell I might give it a try.

Thanks Gary. Will check that in my settings. Think I changed it to speed loading times.

Oh no, at least the Fenix and the Citycat do have a low voltage cut off, respectively lumens step down, but it kicks in at about 2.8-2.9 volts and that’s just right for LiFePO4, because at that voltage they are nearly completely drained. For me it works just right!

Well that’s strange… my xinTD also (supposedly) has cutoff at 2.8, but when I tried an A123 it kicked in at about 3.2 when running on high mode. Wtf?

Also… I was under the impression these cells could go all the way down to 2.2 min. Not sure how output might be reduced, but there’s a fair amount of room between 2.8 and 2.2.

That’s strange indeed, because the A123s hold the voltage very well - as i wrote, even in the PD32 UE at burst level.
The low voltage cutoff should also not be static at a special voltage, but instead should kick in on lower levels, the higher the current load is. At a load of e. g. 5 amps it should kick in at 2.2 volts and on a lower load of let’s say 1 amp it should kick in earlier at e. g. 2.8 volts. Could there be contact drop involved, so the protection kicks in too early?

Yes, most LiFePO4s can safely go down to 2.0 volts, but the energy left between 2.8 and 2.0 volts is nearly nothing, cause at the end of the nearly flat discharge curve, the voltage finally falls off “a cliff”.

with xml, my sample did 1.99a at the emitter on two li-ions, and like 1.5a at the emitter with one. you could always tweak it up with a pot/resistor to preferred output for the lifepos 6v nominal, 7-7.2v fully charged

Not sure UliBar. I don’t think there was an issue with contact. Maybe I’ll try again later to see if it does it again.

Thanks Pulsar. That helps. Think I’m gonna wait til the first arrives before I go ordering another. :slight_smile:

Still open to other options too.

in the mail! hope you like it

maybe a resistor mod can be done on this to get a little more output...

or get one of those 3-18v p60 dropins and rob the driver to put in a two cell host