Pull the batteries out and measure the voltage in them. If you do not have a Volt meter go buy one.
Voltage should be near 4.2. If voltage is much higher, then your charger is no good.
Mine charged for 7 hours, others usually just 5.
could be something wrong on either the batteries or the charger
Tried it out a wow, this light is bright :o. I cannot confirm how bright exactly as i only own a 3W 100 lumen CREE light TL372 from active touch which i can't seem to find anything about :). The brightness at high is 10-15 times that light. I also cannot measure any current as i do not have the tools to do this, and if i had i would probably mess up the light :). The tint is slightly blueish but so much nicer than the greenish tint of the TL372 (lol) and also the hotspot/spill is much nicer! If i read the XML lumen chart at 0,13A at low this light should output around 50 lumen what brings my TL372 at 75l max.
My KD C8 made some 'electrical' noise tonight. It died after 10 seconds, now it's completely gone. Should i be worried?
James , I do alot of spotlighting using mainly ledlensers , P14 P17 and P7 ...the P14 being my fav for size / throw out throws p7 by quite a margin , the P17 is jus the slightest better throw over the p14 hardly noticable but it is and yes its runtime is excellent but you pay for it with size ...anyway I got an Ultrafire 501b with an xre r2 single mode put a DX $3 asperic lens in it and painted out the cree ring and reflector and it throws as far as the P17 and its a midget in comparison and it has a reverse clicky that I dont like for spotlighting , have been told to get romisen forward clicky from shiningbeam but thats more $ You may want to take a look at Solarforce Masterpeice Pro head comes with L2i body for $40 at solarforce hk ....I have one the way and am planning on using the L2t body with the head as its a forward clicky ....keep in touch James and I will let you know how it performs ..but I would think with an air rifle the asperic mod'd light would do fine
...just registered :)
sounds like its is dead.
you can buy another driver desolder the springs and the driver from the pill, then desolder the wires from the led to the driver (not much room to work) and then put it back together i have a spare driver for the one i have that under performs to others but i spent a fair bit of time cleaning it up and resoldering it so i left it as is and gave it to my old man to beat up on it as a work light.
i have brought this to replace mine
Trustfire C8 Stainless Steel Head XM-L T6 900-Lumen
it should be here in a couple of weeks, the wife has already claimed it as her,s
Welcome to BLF, 2ndWord!
Positive at the head , negative at the tail. I hope you didn't reverse it.
The light didn't die, but the strange electrical sound died after 10 seconds :d. My sentence was bad formulated. Apologies for the confusion. If the light itself would have been dead after 1 week only i would have freaked out :d
oh ok glad it is still working for you 
+1
Hi, 2ndWord
501B cant be compared with C8... C8 is much much much better, in terms of throw and output.
I agreed with you,501b t6 can not be compared with C8 Cree xml T6,but for 501B cree xml u2,it will be better,though the U2 is not so stable.
Keep hearing a buzzing sound, but not always and not always as hard.
The driver is having a whinge
how to get over the buzzing sound?