Fenix TK15 and Redilast 3100mAh 18650 won't fit

I just got a Fenix TK15 and find that my Redilast battery is too long. Anyone else have this problem? It will fit in my Fenix PD32 just fine but hangs out of the tube of the TK15 by 0.060" and so the tail cap won't screw all the way down.

The TK15 body is made to fit a 18650 diameter wise, yet, it's shorter than the PD32. I'm rather bummed . Not sure I want it if I have to use CR123A primaries. Anyone running this light with a different 18650?

High capacity 18650 can sometimes be a bit misleading. As you discovered some are longer than others. You could try Eagletac cells, as they are shorter than Redilast cells. I can no longer test it, as my TK15 was stolen.

I have the TK 15 and it works great with an AW 3100mah. Keep that fine Redilast for your next 18650 flashlight.

Thanks, looks like I need a different battery. I got looking at things a little closer and I think I know what the problem is.

Since the TK15 has a spring at both ends, it utilizes a recessed area to house the spring down at the positive end. This recessed area looks wide enough for the nipple of a button top cell but not for my Redilast wider positive terminal (almost flat top) cell. I think a button top cell would sink down into the flashlight a little deeper.........even though the over all length might be longer. So Is the AW3100 a button top or is it just a shorter battery?

I measured the maximum length of battery (not counting the positive terminal) that will work and its 2.655". If the positive terminal makes the battery longer than this, then it has to be narrow enough to fit into the recessed area where the spring is.

Interesting. My Tk15 does not have a sprung in the front.. As it is, the eagletac 3100 fits great, coming to the exact end of the tube, screwing down water tight.

Mine has a spring in front and in the tail. My AW 3100 is flat top. I have no idea whether it is a shorter battery than the Redilast, but the springs allow for quite a bit of range in length. I have also used UltraFire protected in it as well. Much cheaper and they work great.

I've had fit problems with my Redilasts as well, which is why i use AW 3100maH flat-tops, which raises compatibility questions by itself. But anyways, you can always cut off the wrapper and tear off the PCB circuit. That way you'll have a OEM Panasonic NCR18650A cell, which is still quite safe, as most accidents are caused by bad cells, not the PCB circuit.

I Think I'd just buy an unprotected cell rather than tear the pcb off in that case. This does raise an interesting question. Some lights will stop working once the battery voltage drops to a certain level. I'm not sure how the TK15 behaves down at low voltage levels. If that level was above the 2.5v threshold, then I think I'd be more comfortable running an unprotected cell as I'd recognize the need to recharge the battery before it got damaged.

Buy Eagletac 18650 3100mAh. They are very good cells and they will work with all your future 18650 lights.