Low Voltage Protection? I am sure someone has actually tested LVP.
I gifted my first D4 219c Version 1 to a neighbor and he used it everyday and really liked it.
Well he left it on in his truck the other night and it ran a NCR18650GA down to .5 volts.
I have at least 3 D4’s V2 but usually keep charged between 3.7 and 4.1 or so and have never tested LVP.
I would think the V1’s had low voltage protection but maybe not.
Your thoughts on this. Thanks
I found a couple references to low voltage protection in the OP
Wondering the one you gifted was V1, and perhaps that version did not have it? It looks like several people wrote about experiencing low voltage protection in their D4s.
Failed LVP sounds very strange. I’ve tested it using a bench power supply, and it has always functioned correctly. I also actually managed to run down the battery a couple times and LVP did what it was supposed to. Usually I recharge the cell at about 3.3V, but there have been occasions where I used LVP instead.
I agree strange LVP failed but is there any other way he could run the cell down that low.
I have the light and battery that’s how I measured the .5V.
It’s the only 18650 light he has. Guess if he doesn’t get another battery soon and want it back I can test with 1 of my batteries.
It is definately V1 also.
FWIW, putting the cell in backward can make it do that. I don’t think the reverse-polarity drain was fixed until the D4S.
TK you are right battery in backwards most likely. Tried a fresh cell and the D4 is dead.
What exactly happens when someone does that? Does the battery heat up like a dead short and take out the driver also?
It could have overheated one or several components. If you can get a look at the driver (a good picture perhaps?) it would help to identify if there is a burned component. Look for a microscopic black volcano on one of the black components, the MCU or the MOSFET specifically…
Edit: If a component fried you’ll smell it, usually upon opening the light to remove the cell.
That’s why it’s so frustrating. I’ve flashed my two other D4’s multiple times, and other flashlights. Mostly the clip catches on first or after a few tries.
I tried at least 50 times to connect it to it. Flipped it over, tried the other board which worked right away. then back to the new D4. Same result :cry:
I’ve been there as well, know the frustration. Is there a lighted e-switch or something in play here? If there’s anything like that it tends to ground the circuit and can prevent a flash from working. Also I’ve seen the USB actually not making good contact in the computer. Check that the pins are the correct length to make contact in your clip, they have a tendency to slide up sometimes. Check to see if those two capacitors are preventing the clip from sitting all the way down, remove them or remove the MCU and flash it then put it back on. There’s probably something pretty simple and straightforward that’s stopping the successful flash, finding it can be a hair pulling thing, trust me I know!
If the Cap at C2 is stopping the clip from seating, that would do it. Or if the pin 3 is grounded at that pad provided that too would do it, drag an iron across that junction and make sure it’s not bridged.
I usually remove the board to flash mine, you might try de-soldering the e-switch wire .
I started reading this thread and got pretty far in trying to get a feel for which emitter to go for. I can’t afford all of them and didn’t want to commit before getting a good consensus. Finally choose the grainy white body and XP G2 S4 3D 4885. Almost went for my first Nichia but chickened out at the last minute. Maybe next time. Not much written about the white version. Any feedback appreciated. Can’t wait for it to arrive and look forward to playing with it. Thanks all.
Seems like I am always late to the party, just found out about this light and now have an urge to want one. Seems like Mountain Electronics is sold out of all of them except the Nichia. I have tried messaging them last week and didn’t get anything back, anyone know how often they get these back in stock?
the D4 is still discounted at intl outdoor, and all varieties are in stock including the XP-L HI (did not check Nichia). I got mine from there (Nichia 219C), ordered May 30 and received in June 18.
Thank you very much good sir!! I will check them out I try to keep what I can purchase wise in the US, but looks like this time gotta go international. Thank you big time!
:+1: 
Yes , this is one time that ordering from China is advised. $35 vs $40, free shipping, XP L HI option half the price, direct from the manufacturer . It all adds up. Longer shipping to US is the only negative. Also had the only textured option if you are so inclined.
I swapped some Nichia 219B 4500K R9080 emitters into one of my D4s today. :partying_face:
Here’s a first-run D4 with Nichia 219C 5000K 80+ CRI emitters on the left, and the new rosy D4 on the right:
These photos were shot using a custom white balance for each tint. The photos look nearly identical, but the reds get redder.
Click to embiggen:
And here they are compared in a .gif:
EDIT: Photos updated due to white balance issues.
I find the picture looks more true to life on my calibrated monitor with the 5000K 219C’s.
+1
looks like it needs white balance