D4V2 USB rechargeable cell ?

IMHO, the only thing that is missing for the D4V2 to be THE perfect EDC is to be USB rechargeable.

Until a new version comes out, can anyone point me to a good cell with enough amperage that would be great for this light and that has a USB port (USB rechargeable 18650). Something equivalent to a 30Q or VTC6.

Thanks !

There are none. And if there was a high drain rechargeable cell it wouldn’t fit in the flashlight. The charging circuit make the cell at least 5 mm longer.

Cells with built in protection/charging circuits are too long to fit in the D4v2. Max cell length is 67mm.

In order to fit a built-in charging circuit in the D4v2, the overall length of the light would have to be increased. I can understand the utility in having built-in charging, but I’m pretty happy with the D4v2 as it is now.

Thanks for the answer. I figured that the cell would not be 3000mAh because of the charging board. I would be happy even if it was only 2000mAh. I would love to plug the cell on a solar panel.

You could try a USB rechargeable 18350 with an adapter (just put a metal object of the required length at the negative side). That will give you about 1000 mAh. The protection might kick in early, so no turbo or high levels.

Thanks for the idea. In a pinch I guess it could be a solution.

But let’s face it, a D4v2 without high or turbo is like a cheeseburger without cheese !

The D4V2 is 100% water proof. Is it worth giving that up to to be able to charge the battery internally? Unless the USB is on the dry side of the o-ring, it becomes an invitation for water entry.

I totally agree, I was also thinking of an internal protected USB port like we see on many keychain sized 10440 light.

Maybe use a folomov A1 charger?

Yes, not a bad idea. I already own an ANT MC1 charger but my OCD mind liked the idea of not carrying anything else, the light and a small solar panel.

I’m 100% with you on that. Come on Hank, make it an option. I just ordered a Wowtac A6 because of it’s size and charging but a D4 would be better.

A 70mm battery tube would be a good option and I’d buy it. I asked Hank about it by email a while back and he seemed open to the idea.

Here is a 10 amp, usb rechargeable protected 18650:

This one says 8A: https://www.illumn.com/batteries-chargers-and-powerpax-carriers/18650-keeppower-3200mah-p1832u-protected-button-top-micro-usb-charge-port.html

I’m ok with dialing back the d4v2’s max power since it has way more output than I can really use anyway.


Just buy a cell capable of providing 15A-18A and charge it up at home. USB cells are for noobs.


Internal charging is a really nice feature of a light. It’s always good to have less crap to keep track of. It would be nice if the D4v2 had it but it doesn’t. I haven’t tried the USB batteries but they seem like a very clever idea to me as a substitute. Plus,I like the idea using protected cells as a backup to the LVP/OVP already present in the light. Is a 10 amp cell really not strong enough?

Chargers are small enough that I can easily carry one if I need to charge on the go. Otherwise, I’ll just carry a spare.

On board charging is always a trade-off: convenience (not really) vs. much slower charging rates. Same with USB cells. Also, there’s an added failure point if that charging module dies on you.

I don’t do protected cells, as I’m well versed in li-ions. I buy quality chargers and cells, so that’s a big headache out of the way, right off the bat.

Depending on the emitters, the D4V1 and D4V2 can pull upwards of 15A-18A, on turbo, but if you never use turbo, then it’s not a huge loss, but then why buy the D4V2 in the first place, right?


I bought the D4v2 because of the hackable software, though that’s just me.

Slow charging rates haven’t been a big issue. My BC21 charges at 1 amp which is plenty fast for me. I don’t use it on the higher modes for hours at a time. It suffices to plug it in when I get it home, at which point leaving it in the light isn’t such a problem.

In the SAR light thread the SAR guy mentioned advantages of charging the cells in the light, as not having to expose the inside of the light to bad weather. Admittedly that’s not an issue for me.

Protected in principle is only needed for multi-cell lights if the light otherwise has LVP and thermal protection. But if I’m going to be hacking the code, it’s good to have an extra layer in case I mess something up.

I was thinking of buying a light with built-in charging as well since I didn’t want to carry more that what I needed. I was looking at the Sofirn SC31 Pro but also remembered the xtar PB2S charger/powerbank that takes 2 cells. I always have a powerbank with me anyways. Though I haven’t committed to any yet.