LF2XT dimming quickly on 10440

I've been enjoying my LF2XT for quite a while now, and it's my main EDC at the moment. However, for the last week or two it has developed a fault when using Ultrafire 10440 600maH cells.

After about 5 or 10 seconds on high (click then click+hold from CUI) it dims to a little above minimum. 5 clicks to tell the voltage reads around 1.8V, but after removing the cell from the torch it reads 3.8 ~ 3.9V on a meter.

It works absolutely fine on Eneloops.

Has anybody got any ideas please? All help gratefully received.

Cheers
Gord

My LF2XT recently developed some voltage related issues, it was reading high voltages from NiMH, like 3.8, 4.1, just way too high. Same issue on primaries. EliteLED is going to swap out the pill for me.
Mine created a potentially dangerous over-discharge situation by reporting higher voltages, your issue will lead to your light being inoperable possibly when you need it in an emergency.
You should contact the dealer if it's still under warranty.

Your thread may get merged, but please post back with any progress or info.

Hmmm...sounds familiar. I think I had similar problem with my LF3XT. For my case, the fault lies with the battery. I just trashed it.

Out of curiosity, is your batt in grey wrapping?

Sounds like your 10440 is toast. The voltage test in the flashlight is applying a small load to the battery, causing the voltage reading to drop significantly. On the DMM alone there is very little load. You can test this with the DMM by putting a 1 ohm resistor into the circuit when you test it outside the light.

Have you been running the LF2XT with the overdischarge protection turned on? Possibly you overdischarged and damaged the 10440, or possibly it is just defective.

Either way, I would stop using that cell now, and dispose of it safely, and store it somewhere non-flammable until you do. It has a fair risk of going in my opinion, even just sitting around.

bansuri said:

My LF2XT recently developed some voltage related issues, it was reading high voltages from NiMH, like 3.8, 4.1, just way too high. Same issue on primaries. EliteLED is going to swap out the pill for me.
Mine created a potentially dangerous over-discharge situation by reporting higher voltages, your issue will lead to your light being inoperable possibly when you need it in an emergency.
You should contact the dealer if it's still under warranty.

Your thread may get merged, but please post back with any progress or info.

Click to expand...

That could be a possibility as well. :thinking:
Liteflux's indicator might not register accurately, causing continue usage and over-discharge problems.

If you don't have a second 10440 to test in the light, or a resistor to test the cell with outside the light (to see if the voltage sag occurs), then I would definitely recommend not using that 10440 and storing it safely until you can isolate the cause.

Does the voltage report work correctly with an eneloop installed?

Thanks a lot for all your replies, you lot are so prompt! :twothumbs

@Bansuri: I'm guessing the meter in the torch is probably ok, because the dimming indicates that the voltage is indeed dropping too low. I hope it's not the pill because postage back to the supplier will take ages and I don't want to be without it for that long!

@Zeruel: The battery has blue wrapping.

@Jahxman: I'll try with a resistor and see what reading I get. I've had ODP switched on for as long as I remember, although I think that when I first got it I ran for a week or so without. I guess that may have been long enough to discharge the battery too much & damage it. Voltage reported with an Eneloop is correct.

Thanks again, and I'll let you all know the final outcome.

I wonder if the inbuilt voltage test is done under load or not. If it is, you could put it on high, wait for it to dim and then do 5 clicks for a voltage test.
It just so happens that I did a run time test on mine 2 days ago on an old 10440. Fresh off the charger I got 31 mins on high till the low voltage cut out.

It was indeed the battery. Tried two more and they work fine.

Maybe it's my charger, because the two that are ok haven't been charged on it yet.

I'm just relieved that it's not the torch itself, because it would have pained me to send it away, even for a few days.

Thanks again for everyone's help.

glad to hear it work out ok.
i had bought 10pcs of 10440 batteries that show 4.11-4.15V on my digital multi-meter. but will only last 1-2 minutes in my LF2XT on high output. tried all 10 10440 in other LF2XTs and the result is the same. tried them in the LF2X and still the same. so i can only conclude that it is the batteries that is the cause. not the lights.