Foursevens QP2L-X issue?


Newly Enlightened
Aug 19, 2014
Hi Guys,
I've been using a Foursevens QP2L-X for about a year now. For the last few months, I've noticed that instead of the flashlight staying full brightness until it dies, it seems to work for a few days of normal full brightness use (probably less than 10 minutes total per day), then it dims to what I would guess is about 20% brightness and will work at that for a few days. I don't remember this happening before, but I also have switched from energizer to streamlight cr123a cells. I'm not positive if it started happening just when I switched brands or not. I think this light is supposed to have circuitry that makes it so that it doesn't dim at all before it dies, is that correct?


Flashlight Enthusiast
Jul 4, 2007
I think this light is supposed to have pretty good regulation on Max but if the batteries don't have enough juice to sustain Max then it will run at a lower level. Try different batteries and if that don't work you may want to send it in for warranty repair. You should consider getting a 16650 or 17670 rechargeable battery for this light, XML's running at high current levels eat cr123's like rats eat cheese.
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Flashlight Enthusiast
Mar 25, 2007
.... I think this light is supposed to have circuitry that makes it so that it doesn't dim at all before it dies, is that correct?

As LW said, this light (most regulated lights for that matter) will hold a flat regulation as long as the primary batteries can sustain the amperage, and then go unregulated steadily dropping in output as the battery dies (assuming a max runtime test). If you're intermittently using the light with dying batteries, then what you are probably seeing are the primary cells recovering, and the light operating at the highest mode it can regulate at (probably med or low), regardless of the tight bezel setting. Eventually the light will run on moonlight only.

It's highly advisable not to run CR123s used in series too low though - if the cells are mismatched in capacity, for whatever reason, you run the risk of a reverse charge (stronger cell starts charging the dead cell in reverse polarity) and the battery venting with flame (= explosion in an airtight tube).

That said, if you're not getting a reasonable amount of runtime at full power on max, then perhaps something is wrong with the light you should send it back for warranty repair... 47s customer is excellent.