4 X CR123A battery tube for inside flashlight?


Flashlight Enthusiast
CPF Supporter
Jan 27, 2017
Dirty Dirty South

I owe a debt of gratitude to the OP of that thread. Last spring, one of my 18650's vented with flames on the charger in my living room. Because I'd read his report, I got my wife and myself outside immediately and avoided all contact with the fumes.

I hope this won't be off topic, but I do still use 2xCR123 and 2x18650 devices, but on a limited basis and with care, always having an escape plan in mind should things turn ugly.


CPF Supporter
Aug 9, 2015
My own little Idaho
I suppose before inserting primaries a quick voltage check is in order. Especially ones just received in bulk.

I had a plastic 2xaa light poof on me in a grocery store parking lot. Thing is I had been using it, ran up to the store real quick to grab a pack of smokes with it in my jacket pocket. I felt my pocket getting warm, warmer, hot as I was entering the store. Pulled out the light that had swollen and tossed that sucker when "pow" like a firecracker....
It was a deal where I had pulled 2 leftover batteries from a drawer and slid them into the light.

Lesson learned that in this case one battery was apparently trying to charge the other that had a lot less voltage remaining.
I never use leftover batteries in pairs ever since and when a new load of 123 primaries arrives I check voltages, then store in a smaller container to pull from when time to reload a light. Either that or pre-load 2-3 cell magazines.
Any that vary significantly go into a separate container for use in single cell lights.

And I DO NOT USE primary batteries made in China. Too many fakers in that region so there's no telling what you get unless you know for certain the seller is above board.

So hopefully whichever solution the op decides to use with his 4x123 light, a voltage check will be done before batteries are inserted.


Jun 2, 2009
Not that it is anything to do with the topic but I only use Surefire batteries fresh from the box (3.25 volts) and always test voltages first when I use batteries in series. Entirely anecdotal I know but I have had two lithium ion batteries go into thermal runaway. One vented no flame. In each case sitting in a single cell flashlight that was not in use. One occured in a RCR123. The other in a single 18650 P60 setup. In both cases they were the best quality and highest rated cells of their day purchased from very highly respected American dealers. I have never had an incident with primaries although I am fully aware of many many reported incidents.

I think nonconductive tape wrapped around the batteries creating 2 sets of two is as good as any other suggestions and what I will stick with.

I am using primaries because the flashlight is kept in my car and we have had several subzero days this winter. Not conducive to li ion use.

My pocket edc is a Zebralight 62w so I am not afraid to use li ion when appropriate.
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peter yetman

Flashlight Enthusiast
Mar 23, 2014
North Norfolk UK
If Arch and Rec don't mind me straying off topic a bit...
I'm going to be running pairs of IMRs in series with a couple of Oveready heads.
Bearing in mind what has gone before I'll obviously be cautious.
Is there a way of measuring IR with a DMM or does it need the algorithms in an Analysing Charger?
The chargers I have seen on HKJ's reviews that do this, don't seem that durable. Or for that matter very accurate, he normally says something like "As usual I wasn't impressed with the IR function" or similar.
Your ideas will be appreciated.