I have 2 of the UT01 lights, and both have the known issue where if you are using a 14500 cell, you need to unscrew the tailcap to break the circuit in order to turn the light back on. I really like the size, UI, and performance of these little lights, but I’d really like them to work as intended with a 14500, without having to do the unscrew the tailcap thing. I don’t know if this is a switch or a driver problem, or maybe both, but I’m wondering if anyone that has had the same problem has successfully fixed theirs, and if so, how?
Bump
The first one I bought worked for 2-3 days then the same problem showed up, bought a second one and it has been working fine for the last month, I also really like these lights and they would make a great light to gift if they could get them to work right.
There was another member who did a complete tear down on his light and was able to buy a bunch of switches and fix the problem. His findings were the microprocessor and software are collectively very sensitive to switch tolerances.
I have 4 of them working fine, but I’ve only been using Eneloops and lithium primaries - and I’ve clipped the outer tail cap springs in all of them.
Have you clipped the springs or otherwise addressed the ‘short tube / crushed driver’ issue, or is it definitely a voltage issue?
Both of mine work perfectly when using Eneloops, and I haven’t tried Lithium primaries since I don’t have any. When I got my first UT01, I clipped the spring on it before I ever put the first battery in it, just so I wouldn’t possibly crush the driver. It didn’t make any difference when using a 14500, still had to break the circuit to turn it back on. Haven’t clipped the spring on my 2nd one. I had sent a PM a while back to the member who did the successful switch replacement (Lexel?) to try and get some feedback and info, but never got a response 
If anyone knows the correct switch part number and where to get them, let me know and I might give that a try. Otherwise, I still REALLY like these little lights even when using Eneloops. If I had known about the “basically the same” Lumintop EDC05 at the time, I probably would have gotten that instead only because it has the magnet in the tailcap. Really handy to have that feature, just like my OTR M3 and my Olight S30 Baton have.
Yeah I think it may have been Lexel (??)… AFIAK he is the only member to have permanently fixed this problem. Somewhere on BLF is a lengthy technical discussion on it. Most of the theories behind this are way beyond my scope of understanding.
Tom E did also a repair:
First post [Ended]Groupbuy : Utorch UT01 (XP-L , AA & 14500 battery , e-switch etc) - #415 by Tom_E folgend
- LED + leads AWG 24 changed, solder on contact ring , NO-OX-ID
- MCPCB is Aluminium 0.95mm thick, replaced by a Noctigon (reworked it) LED changed: XPL2 with 4000k
- Overview: [Ended]Groupbuy : Utorch UT01 (XP-L , AA & 14500 battery , e-switch etc) - #425 by Tom_E
Joe
Heard back from Lexel, and the new switch that he used is available at digikey. He recommends using hot air for soldering it. Since I don’t have a hot air system for soldering, I may wait a while to try replacing the switch.
“https://www.digikey.de/product-detail/de/e-switch/TL3340AF160QG/EG4627CT-ND/1885974”
Hello
Someone knows if utorch ut01 manufacturers solved the problem in the factory.
the units that are bought now are fine?
a greeting
Good question. Seems no one knows yet. Maybe no one is buying it at the higher price.
Hmm… Maybe that’s why they WERE cheaper…
Yeah, that’s my reason. Really hoping around Thanksgiving or Christmas we might see the $10 deal again.
I don’t know why people keep buying these things. Seem to have a huge failure rate.
One of my UT01 lights does this on both 14500 as well as NiMH cells. Sucks. It was fine for the first 6 months.
How long ago did you buy them? One of the sale models?
I had one little used UT01, and one unused UT01 that worked fine with 14500. I put high CRI emitters in them and started using them more. They were fine, then after a week or so, the one I used most developed the problem, so I switched to the second one, which also worked fine for about a week, and then also developed the problem.
They still work on NiMH, and I’m still using them, but I’m never buying another, and don’t suggest anyone else does, either.
Yup, it was one of those $10 sale models, purchased in November of last year.
The other one I bought also for $10, in October of last year, still works fine.
I fixed it. Found a great way.
Ahh… the “bang good” tool… I’ve gotta get me one of these.