Mag 2C and protected 18650's

I ordered a pair of protected 18650's for a new Mag 2C from AW and he says his won't fit

It looks like the light has 5.2 inches or 132.08mm of room. On another thread someone said their AW protected 18650's measured 66.5mm. Times two that would be 133mm, just a bit too long. I haven't heard back from AW on length yet.

AW's protected 18650's are 2200mah. His 18500's are 1400mah. I'll probably use a KPR112 bulb rated at .75 amp. How do you calculate runtimes for batteries in series?

I'd hate to have to go to 18500's and lose 57 percent capacity because I'm off by one millimeter. Does anyone know of a brand of protected 18650 (and where to get them) that will fit in this application or have another protected solution?

AW's batteries sales thread:
https://www.candlepowerforums.com/threads/97268

You have to take material from the end of the tail-cap deanodize the interior of the tail-cap and use one of the small magnets and a thimble of aluminum foil as the negative ground.

Or look for some ring that will fit the exterior of the tail-cap and close the gap bewteen it and the end of the tube, if you don't want to drill material out.

Juan C

AW emailed back and said the shortest protected 18650 he could find was 66.26mm.

juancho, I already sanded the annodizing off the base of the cap. I see what you are saying now, don't screw the cap down all the way and have a spacer ring to fill the gap between the cap and the body of the light. That would work, but you'd lose the O-ring seal.

The base of the tailcap appears to be .080 inch thick. I really don't want to machine it thinner.

I could just go 18500's and then I could keep the spare bulb in the cap and only have to modify the spring a little. Can anyone guess what a good runtime would be on 18500's and a KPR112?

If the KPR112 is rated at 750mA, you should have close to 2 hours runtime on a pair of 18500s.

Since an 18500 cell is about the same length as a C battery, why not do as AW suggests and use 2 x 18500 in your 2 C, and either use a KPR112 (6.0 v) or KPR118 (7.2 v) bulb? Just go to your local plumbing or hardware store for a piece of PVC pipe that is the same o.d. as a C battery, but just slightly larger i.d. than the o.d. of your 18500 cells.

Either that, or use 3 x RCR123A (16340) 3.0 or 3.6 v cells, and go to the same stores above to get a piece of silicone drain tube that has the o.d. of a C battery and the i.d. slightly larger than the o.d. of the 16340 (you could use the same PVC pipe, but the cells will rattle). Now you can over-drive a KPR118 bulb or possibly drive a KPR120 (12.0 v) bulb.

No removal of anodizing, nor additional of bolt, nut and washer extender, required.

See:
- http://www.servicelighting.com;
or
- http://www.lightbulbdepot.com
for boxes of 10 of these bulbs, or other types of bulbs.

I want to use the 18650's if I can for the much greater capacity, 2200mah versus 1400mah for the 18500's. A few people have mentioned using 18650's with the 2C, I was hoping someone knew of a protected brand that would fit. In my case I need two cells no longer than 66mm each, preferably 65mm.

I've done the 3x123 mod already, so I'm familiar with sleeving the flashlight. I'm impressed with the amount of light just using 4 watt bulbs. Now I want to be able to use the light without worrying about how many batteries I'm going through.

The most capacity I've seen for rechargable 123's is 750mah. That doesn't seem like much at all. How do you compare 3x123 at 750mah to 2x18500 at 1400mah. Am I right to think you'd have more capacity with two 18500's?

At the moment, I don't have any protected 18650s but they will fit... I don't see how they could possibly not fit... Just the tailcap wouldn't screw all the way down and would leave maybe a 1mm gap between the flat part below the threads and the end of the flashlight body.

This would compromise water resistance, but nothing an O-ring or two wouldn't pretty much fix.

AW, if this is not the situation, please chime in but since AW's unprotected 18650s fit with about a millimeter to spare, I'd imagine the protecteds would fit but be 1 millimeter too long.

Two protected 18650s will be about 1 - 1.5mm too long for the 2C body. If you don't mind adding an o-ring, it may work.

I have 2, 2C Tri-Lux lights using AW's protected 18650's and they fit.

I use a thin wafer of aluminum foil for the negative contact in the tail cap, the last turn on the tail cap is a little tight but not cell crushing.

Not all cells or Mag's are created equal so YMMV a little

Later
Kelly

There's a thread somewhere about adjusting the mag switch to push it forward just a hair, but I'm not sure where now. Maybe in one of the ROP threads? This could give you some exta room.

Ya, just move the switch forward a touch. You should make your own really short spring to go inside the tailcap too. The 18650's fit great.

Basically, the same mod as I did here:
https://www.candlepowerforums.com/threads/97026&highlight=diet

If needed, I can take more pics.