Can I use 2xCR123's in a Klarus XT21X?

I just received a Klarus XT21X and played around with it a little to test out the modes and beam pattern. I noticed on the side of the box that it says "Working Voltage: 2.5V-6.4V." I have a couple 21700 adapters for 2xCR123's (and an 18650 adapter from a vape mod). Do you think it's safe to try 2xCR123's in the flashlight?

Update 2/21/2021: Tested with CR123's and it works, but without the higher output levels...

I just wanted to know if it would work if I had to use CR123's primaries in a pinch. It seems like the same amount of light is put out above the low mode (didn't do any long term tests). Since the low mode (100 lumens) of this flashlight is what I use most often, it's nice to know it's available. Additionally, a spacer would probably be required because of the missing length compared to a 21700. The springs were long enough to make it work with an 2xCR123 to 18650 adapter, but would break contact with the slightest movement.

Adapters tested:
1. Eagletac 18650 to 2xCR123 adapter (fit but too short without a spacer)
2. Nitecore 21700 to 2xCR123 adapter (too wide to fit in the Klarus)

As a side note, the Nitecore P20i I took the adapter from still retains all three modes with CR123's (except high is limited to 1,100 lumen instead of 1,800) with slightly shorter run times. The i4000R states a loss of Turbo mode on their website with 2xCR123's.

Update 2/22/2021: Tested with a 2xCR123 to 18650 adapter inside an 18650 to 21700 adapter. Fit fine, but only the 5, 100, and 400 modes available/visible. I only tested for function and did not test for runtime.

I assume the normal cell is one 21700? I can't see why you couldn't use 2 CR123s instead, since together they max out at 6.0 volts. But I wouldn't try two RCR123s, since at a nominal 3.7v each, you would be exceeding the 6.4v limit. I will leave it to others who will be more knowledgeable to weigh in on using two LiFPo3 cells.

When it comes to batteries, two is not one, and one always has a greater degree of safety. :welcome:

Smoke and Fire, Hot Cells and Close Calls - The dangerous side of batteries

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Two cr123s' will likely be too short for the 21700 length battery tube, rattle around issues.


just stick w/ your 21700 cells.

I just wanted to know if it would work so that in a pinch I could use CR123's when I have no access to a charger, spare 21700, if power is out, etc. I just didn't want to test it out if the 6.4+ voltage when new might damage the LED. I think I'll give it a try and see how it works out. I'm not expecting the same output, but just wanted to know whether it would damage the flashlight if used with CR123's if I had no other options.

No, I'm not thinking of using 2xRCR123/18350's.

Thanks for the responses.

Edit: Tested and updated OP.

Two 123 would be under 6 volts when under use but you might want to check the draw. Most don't get a warm and fuzzy if 123 draw over 1.5 amps.

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I see you updated your OP

A 18650 to 21700 adapter will take care of the difference in length and will also, of course, facilitate the use of 18650s. You could also run it on a single CR123 (at reduced output) or a 16340 with a 16340 to 18650 adapter. I have 3D printed some of these along with 14500 to 18650 adapters.

xxo said:

A 18650 to 21700 adapter will take care of the difference in length and will also, of course, facilitate the use of 18650s. You could also run it on a single CR123 (at reduced output) or a 16340 with a 16340 to 18650 adapter. I have 3D printed some of these along with 14500 to 18650 adapters.

Click to expand...

So would it be a bad idea if I fashioned a 2xCR123 adapter for emergency use? I just like to have an option for locally available batteries when in a pinch without a recharger or other available rechargeable batteries. If it's a bad idea, than I'll relegate this flashlight for general work and leisure, rather than including it in my emergency systems.

You could make a 2XCR123 adapter or just use a 18650 to 21700 adapter with or without a sleeve to take up the difference in diameter.