Hi all have a question are the Panasonic protected 3400 MaH , 3.7 volts too much juice for the C8 LU3? If so what is recommended as a good battery? I ask because I believe I fried the emitter after only 3 days thanks for any input.
You are using the correct battery if its a 18650 compatible flashlight. Is it this light. Its not the batteries fault the light died unless the pcb is tripped, maybe a short, bad driver, bad switch, bad connection, bad led.
Take it apart and see what you find. Post your findings here and maybe someone can help. Pics are also helpful.
I believe it is the one from Lightmalls one knowledge members if this forum suggested it may to hot I am inclined to believe he may be right, but manufactures specs say its regulated 4amp so I figured the 3.4 amp would still be on safe side.I ended ordering 6 of these lights as I liked them so much but. I’m pretty new to this .I ’ll be honest I am not yet competent to disassemble and reassemble these lights yet.
If you have a DMM you could take a tail cap measurement to find out what the current is with one of the other lights.
When it comes to china specs there hardly ever correct with lumens, current, and battery capacity. They exaggerate (lie) the specs so you will get all beady eyed and buy it. 
Sometimes current regulated means direct drive in china. 
One reviewer says 2.8amps? Doesn’t say anything about being current regulated on lightmalls site. Says “Max 4000mA Current Output (manufacturer rated)”
I have this light from lighmalls, original driver was 1,8A on high, I swapped the driver with a nanjg one, and works without problems at 2,8A on high.
First thing you should always do if your light isn’t working is to check the tailcap. A lot of the time the problem is a poor connection, and often these budget light tailcaps are problematic, but easy to fix:
This picture shows how to do it, but all you really need is a screwdriver. Remove the tailcap. Use the tip of a screw driver or wire to connect to the negative pole of the battery, and make a connection to the inner flashlight tube (where it has no anodizing, it’s silver). If the light lights up then it’s a tailcap issue, and easy to fix after some fiddling.
I’ m just wondering what other members got for a true reading I guess I’ll have to get a meter it won’t be an y high dollar Fluke or anything like that remember its budget light forums lol thanks for the pictures walking me tbrough ill get back after readings
sorry for taking so long to reply I am now just getting around to getting paraphernalia (multimeter) for my new addiction but would you mind walking me through the settings on meter? Thanks I know it’s basic for you flasaholics
Try here from member HKJ.
http://www.lygte-info.dk/info/Measurement%20UK.html