Convoy M3C battery unexpectedly dead

I haven’t used it in a while (a couple weeks maybe) and the battery is dead. I forget what it was at last time i used it but i never ever store any flashlight dead. Suggesting parasitic drain, though i cannot determine the rate.

Anyone else notice this or has measured it?

Also the built in voltage check first read 3.7V then a minute later (no use) read 3.5V. This is unusual in my experience, voltage drop on no use is not a lithium characteristic, its an older battery but was tested at 4500mAh (above 98% of new) a month or two ago.

On the interesting side the output is so low i am going to take a macro photo of the XHP-70 chip and will post it here if it turns out.

I took some pics but could not get good ones, i need a better camera to pull that off. Notice the PWM.
But on one pic you can sort of see the stippling effect that was on the LED chip. All pics taken at the same moon level brightness but different exposures.
Click for larger image.



So i pulled the battery and tested it on the multimeter. It read 3.71V which is most certainly not dead so i threw it back in the light and it works fine now, full output is working perfectly. I will charge it back up to 4V.
So either its a software bug or the battery contact was somehow messed up (yet it could work on very low moonlight). I suspect software bug.

Not sure what happened there, but it is using a boost driver which cancels out Turbo at 3.7 volts

I am a little confused because you say the battery was dead and then somehow took macro shots of it switched on.

I never rely on the battery check function, I very rarely use it, and if I use it it’s just getting me a rough indication

It turned on on a very low moon mode, lower than it normally has, maybe 1/20th of its moon mode.
It would not go any higher.
But the voltage check worked, it said 3.7V. Tested again a min later it said 3.5V.
Then i took the pics, the camera is right up to the light but i would guess its putting out 1 lumen or less. The shutter rates and close distance make it look much brighter than it was in real life.
I could see the stippling in the LED chip like you can kind of see in the PWM pic.

So then i pulled it and tested it on the multimeter, which said 3.71V.
So i put it back in the light and it works fine.

Sounds like it thought it was low battery or something. Have you cleaned all the contact points and checked the retaining ring to make sure it’s got a solid connection

Its practically new. Less than 5 hours runtime on it i would guess.

I just had a look at the contacts and everything looks good.
If it does this again i will clean one contact at a time to see if it solves the problem.

Many new lights arrive looking perfect until I clean with contact cleaner and the rag tells a different story

Fair enough, every now and then i clean and regrease all my lights, been a while since i did them all.

I measured the parasitic drain on mine when I first got it. I can’t remember the exact value but it was in the micro amp range. My UI sometimes goes crazy and I did have to clean all the contacts once to make it work properly again. When I first got it it would step down even when the battery was above 3.7v with the included battery. The Shockly 5500 works fine in it though.

Great light when it comes to sustaining output and heat management. These type of drivers can be a little touchy. I have the same issues with my Sofirn SP33 V2 with regulated driver. UI goes nuts sometimes. Usually unscrewing the tail cap and retightening resets it along with cleaning. Spring bypasses help with both .

Edit: just measured 44 microamps on mine.

pennzy wrote: Edit:

That is 385 maH in one year.

Thanks for checking that.
So this means its either poor contact or a software bug.
I have charged the battery to 4V and put it in the flashlight which is back on the shelf, i’ll try it again in a few weeks and see what happens.

Same or similar issue. Parasitic drain of around 27mA when off. It’s a bummer but answers why my light is dead after being not used for a few days

Yes, 236 AH for a year, 45.9 AH for a week. Wish I had a battery that could do that!

I just checked mine which was unused for 12 days, it went from 4.0V to 3.9V and didn’t display the same not working behaviour from last time.
So i don’t think it drained that much and i can’t explain why it went wonky last time.

Mine was a piece of crap from the get go. Cleaned changed battery etc ad nauseum etc. Only convoy I ever got burned on. Ain’t worth an email war just got a bad one I guess. Hope you figure it out

Sounds like you got a defective one.
Keep on Simon, btw if you paid with PayPal they have a 180 day claim period you might be able to take advantage of.

That would take 128 days from full charge though, if using a 5000mAh battery. 27mA is higher than I’d like to see though