I cant help with any good ideas but I'm here for moral support. Did you try unprotected batteries? I guess that would only point you in the direction of the problem though.
Measure voltage. Its prob your batts. I have 1 set which is just like average, it powers other lights ok like UF U-80/UF-980 ok. In this it will just ramp up the current when voltage goes down, and if the cell is just merely average the current would shoot up as the regulation circuit tries to compensate. Then its either the protection circuit in the cell that cuts in, or the voltage sags so much that the driver voltage protection cuts in.
Do this test, do a current reading at the tail for a couple of minutes till it shuts off. You could see that it goes from say 2.9A to as much as 3.8A. From 3.2-3.8A it probably rises pretty fast within 10s. This means the batts are unable to provide the juice. You see the phenomenon of it able to come on again after rest coz it has recovered, then the same thing will happen again.
Ahh...mystery solved. 4.4A, too much for your cells, even if they are unprotected the voltage probably sagged and the driver voltage protection kicked in. Charge them up first, match them (which is very important, 1 lousy cell spoils the whole show), and see if you get improvement from say 5 min to 15 mins.
Good cells to use include Solarforce V2 18650 - 50 mins run time on high.
Panasonic NCR18650 2900 - 60 mins. Get from HKequipment for 19.90 shipped for 1 pair. Same stuff as Redilast or AW but cheaper. These are unprotected but the driver will protect it and it works every time.
Hi Max 2600 should work well, get 6 and its cheaper. (Ebay)
One last thing, if you are getting that "current suddenly shoots up from 3.0A to 4.x amps" reading, 100% its the batteries that are incapable of providing the juice. They still work in other lights, just not this puppy.
Test the rear switch by removing the tailcap and connecting the battery to the body with a piece of wire (paperclip, whatever). I had a similar problem with my WF-502b, and it turned out to be a bad switch.
(my symptoms were basically the same, but mine only went for a minute or so until shutoff. on partially discharged batteries, however, this problem disappeared)
Edit: Everyone elses answer makes more sense... my diagnosis just involved tinkering 'til it worked.
Glad to hear that it is due to the battery. It is a happy problem, that means the voltage protection is always working....perhaps set a little high, but its for the general good.
I had the same problem with my specimen. I found out, it was the contact between the end of the battery tube and the pill. There is a threaded ring which holds the driver board in place. It has a spring underneath, so there is no problem to losen this a bit (a half turn) to get a firm contact to the tube. Well, this fixed the problem in my light. Give it a try, it's cheaper than new batteries.
I've just ordered the skyray 3800 lumen from ebay. came with 2 ultrafire 18650 batteries. I'm having the same issues as described earlier, after less than a minute on high it turns off etc. Is it the batteries that are the problem or a faulty connection?
they're are the red ultrafire ones. I was planning on sending it back and ordering different light. are there any lights with equal power as this one but still cheap that you could recommend?
Some-dude, the problem is with the batteries. Even with a single XM-L light but driven at full power, you might have an issue if it has low-voltage protection. Ordering another light probably brings you back to square one.
You can order the XTAR 2600 batteries, they are supposed to have Sanyo cells inside. Very good and safe stuff. BTW for the light, try not to gun for over 10 mins, the LEDs can take it, but not the driver. If it's very cold in your country (below 5 deg C + slight breeze) you can try for 20 mins.
