2x26650...unsafe?

[jabe1]

I'm in the process of building a 2D mag XM-L.

Would a 2x26650 using IMRs be unsafe? Should I use protected cells. I know these cells are capable of very high draw if they short accidentally.

I typically use only singles in any high draw application for fear of unbalanced discharge, but the IMRs are supposed to be more tolerant, or am I missing something?

Opinions please.

 

[LEDAdd1ct]

I would say that if you use cells with closely matched voltages, check them before inserting into the light, remove them and check them frequently, and make sure they do not get discharged too deep, you will probably be okay. But running these high current cells in series always carries some risk. Keeping a volt meter at your side is a good solid step.

I've never seen protected IMR cells.

There are battery experts here who will hopefully chime in. Mr. SilverFox is the man when it comes to these sorts of questions, and I would defer to him.

I do not run li-ion or IMR cells in series in any of my lights out of an abundance of caution, but there are plenty here who do.

Good luck! :)

 

[Colonel Sanders]

I run 2x and 3x26650s in my hotwire lights. I always check the voltages before installation to be sure they are within .02v of each other (just my method.)

Start off with cells that are bought at the same time and always check that the voltage is matched before installation.

 

[jabe1]

Thanks for the input.

I'm still a bit hesitant, even though I've been running 2x18650 in a ROP for some time.

Has anyone tried a 2S 26650 light with 4sevens batteries?

 

[KiwiMark]

make sure they do not get discharged too deep

This is good advice - unless they are 100% perfectly matched one will drop in voltage a little ahead of the other, but if one is 3.4V and the other is 3.5V when you remove them to recharge - they are fine as both are above the minimum. Generally I'll remove and recharge the batteries at the first sign of the output dimming. I have a light with 5 x 26500 IMR cells and it still works fine: http://www.youtube.com/watch?v=G02lhjvtQZI

 

[Nokoff]

I run 3x26650 protected 4Sevens in my homebrew incan that pulls 5+A....ran almost an hour tonight, varying modes, down to 3.84/5 between the three of them, so I'd say they perform pretty well. I'd switch to safer chemistry IMR but I'm not sure I want to give up this kind of runtime. I ALWAYS check/match them off the charger before use. I can recommend them for use in series and their protection circuit can handle 5+Amp

Thanks for the input.

I'm still a bit hesitant, even though I've been running 2x18650 in a ROP for some time.

Has anyone tried a 2S 26650 light with 4sevens batteries?

 

[jabe1]

I run 3x26650 protected 4Sevens in my homebrew incan that pulls 5+A....ran almost an hour tonight, varying modes, down to 3.84/5 between the three of them, so I'd say they perform pretty well. I'd switch to safer chemistry IMR but I'm not sure I want to give up this kind of runtime. I ALWAYS check/match them off the charger before use. I can recommend them for use in series and their protection circuit can handle 5+Amp

That's what I wanted to hear! I've been wondering about the protection PCB on these.

 

[Nokoff]

fyi I use an AW soft start to get them going, if not it would trip the pcb

That's what I wanted to hear! I've been wondering about the protection PCB on these.