JetBeam Jet I MKII and Li-Ion 14500s

OK, so I really like the Jet I MKII I bought, but I wanted it to be brighter. Seeing that others had used rechargeable Li-Ion 14500s, I decided to give it a try. All I can say is WOW. I haven't measured anything officially, but this light with the 14500 is noticeably brighter. I don't know that I can ever go back to using an AA in this light again.

I did note a couple of things: First, the protected 14500s I got from Lighthound fit into the MKII with absolutely no problems. A few people have mentioned that the 14500 in the MKI was a tight fit--not the case with the MKII. Second, all modes worked fine (normal, low, high, strobe), even with the battery hot off the charger--I was under the impression that batteries right off the charger would direct drive the LED, and the various modes would not work until the battery voltage dropped somewhat.

I used a Pila IBC to charge the batteries, but, as the batteries are new, they may not have reached a full charge. Unfortunately, I did not have any test equipment with me. When I got home from work, I tested the open voltage of the 14500 I was using, and it was around 3.7 volts. If the batteries did not reach a full charge, that may explain why all modes worked with the batteries straight off the charger.

Overall, I am really impressed with how this light performs with the 14500.

It IS direct driving the LED with a 14500 right off the charger, but the modes still work. Then it should drop into regulation. You shouldn't be able to detect any of this btw. ledcandle did a graph of 14500 when they first came out. Not sure where it got to though.

Yeah, it's bright alright on 14500's, amazingly so. But it heats up so fast even on medium level that it halfway scares me. And the runtime is pretty lousy. I'd like to know what the current level is on high with a Li-ion. I think I'll stick with nimh in mine most of the time........

Duracell 2650's were a little snug in my light at the clickie end. I ended up simply boring out the constriction on my lathe. I believe the AW protected 14500's would have been tight also.

Dan C

This light really rocks with the 14500, I use one in my Liteflux also!