CR123A in C8

Has anyone tried putting CR123A primaries in their c8? I know they are 18650 lights but cant help but wonder if they could run on primaries without going poof. I am not looking for more output but think that the c8 would make a perfect vehicle light if not for the li-on batteries. If it did blow what would fail? The emitter or driver? I know we frequently move up from a single primary to li-on without issue so I wonder if 4.2 to 6vt is too great of a jump for these lights.

It would depend on which C8 you have and the emitter/driver combo in it.

Pretty sure it is this one. I know it says 3.7-4.2 volts but still wondering. Iirc the 8x7135 driver on KD says it is rated up to 4.5vt but when someone asked why it wasn’t rated for 6vt for primary usage they replied that 6vt would be ok. Just wondering. I might have to take a chance and try it. Worst case scenario is I might have to try my first driver or emitter swap.

AMC7135 chips can get extremely hot when the difference between Vin and Vf is high. I tried running 4.8 Vin with a 7135 driver, Vf was about 3V, and that was enough to trip the heat protection. My guess is that running 6 Vin with a 8x7135 driver would notably increase the risk of damage to the chips unless the driver had great heatsinking.

That's probably not AMC7135 based.

I don't know what's in it, but my guess is that you'll fry the driver before you fry the emitter in that one. You might as well give it a try if you don't mind swapping the driver in the end.

well just killed an ultrafire c8. So there goes 13 bucks. for your answer.

Sorry to hear this but how'd you kill your light specifically?

Can't answer all of the questions asked manxbuggy1, but I ordered just this past week the C8 seen here which the OEM's rep and the website says will do 2xCr123a's/6 volts.

With a DMM and some matched Duracells in hand - or maybe a pair of those matched cells a dealer offers - I'll prob'ly give this a shot at some point after confirming with the manual.

Well I just put the cr123a cells in and turned it on and no poof yet. It seems possibly a little brighter but not drastically so. I will slowly extend the run times on it until I am comfortable that it is ok. Hopefully I have me a nice all around light to put in my car now.

Sorry about that feilox. I did not mean for someone to sacrifice their light for my answer. I feel bad. I was just hoping that someone had been curious in the past and had tried it. So far mine hasn’t blown. Did yours go right away or did it take a while?

From my few months lurking here and scouring 'round the web I wouldn't feel comfortable keeping long term > or = to 2xCR123a's in a light, i.e. only one. Recently bought a cheap two-pack at wally-world of Energizers that measured slightly different on my DMM and would've gone back were they meant for the same light long term (ok for the two trustfire mini-01's)... more experienced BLF'ers please feel free to respond.

Anyway, I'll stay with Duracell primaries...

It lite up bright right before i tighten the bottom switch on, Id say 1/4-1/2 second… then off. The LED was sort of like moonight mode for the rest of the time… I procede to turn if off, take the refelector off. Place 2 cr123 back in… moonlight lumens… I noticed it turn bright if i put pressure on the LED… I proceeded to tighten it… after putting it back it won’t even have that moonlight mode… By moonlight I mean, it glows white I’d say 1-10 lumens. But it stopped so i took it apart.
It stopped shining altogether. Some melted black parts on the bottom on the other side of the LED and some melted solder that’s it. a faint smell, not as bad as exploded batteries. LED doesn’t look burnt but I’m sure the drivers inside are fried.