Batteries: 18650 or 26650? Low or High discharge?

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OK, the 26650s are on charge. A Piglet (1- 18650) and the PV52 (4- 18650s) just went into their water baths at 11:30.

The only thing I don't like about the Video Lights is that they are not button operated so you can't dim them. You twist them on or off and there's no inbetween. I'll be running the tests on the Piglet and the PV52 a couple of different ways. In the cave when I'm by myself, I prefer the PV52 on half brightness. I also want to see how long it lasts on the UV setting. The latter is more for OW diving on reefs. The UV is so freaky at night and I love it.
 
FWIW, I use the 18650 from SubGravity. It's a Panasonic (Japanese Cell)with a Subgravity "wrap", protected, and kicks butt. I use it with the DGX600, and I will go to my grave swearing it's the best dive light PERIOD, $49.95. I have the NiteCore D2, which I love as well. Charges the 18650's, my Eneloop AA's for strobes, C cells for "my other dive light", and AAA's, for my night diving flasher. Also FWIW, the DGX600 outshines the DRIS 3 C cell dive torch. I have both, and I've ran them both at the same time on dives, and I keep coming back to the DGX600.
 
Forty minutes into the burn, both lights changed intensity. 50 minutes into the test, the Piglet switched off. The indicator light had been flashing red just before that. The PV52 looks like it's running at half brightness. It's still hard to look at the reflection through the glass off of the end table. Piglet in with a new battery at half intensity.
 
2:00 pm: the PV52 (2.5 hours) is now dim enough to cause issues in a cave.

The Piglet on half brightness (which is still plenty bright for me) has gone an hour and a half and the charge indicator is still blue (full).

EDIT: the video light with the fully charged 26650 went on at 2:10pm.

Also, the indicator light on the piglet just changed to red just before 2 hours passed.
 
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An hour later and the Video light is about half strength.

The piglet's indicator started flashing about 2:45 and died before 3:00pm. That's 2:15 on the 1865o battery. The PV52 went in on half brightness at 3:15pm.
 
To me the most important thing was to get a smart charger. The packages that come with a charger usually suck and the charges do not do a good job of charging. Also to know that I need to buy a pack of 10 batteries like that and toss them out as they go bad.
 
The Video Light died at 3:40 pm... about an hour and a half on the 26650 battery. Not much of an improvement, but it is an improvement.

The PV52's indicator is green after an hour of use.
 
My recommendations after researching, getting different ones, and using them for the last 3 years:

For 18650: Panasonic 3400mAh (green)
For 26650: KeepPower/EVVA 5200mAh (black)

All of them protected, button-top.

The majority of these batteries sold on Ebay/Amazon, and many other places, do not have even close to their listed capacities (Ex: fake).
Those will say something like 6000mAh, but in reality are 1/3rd of that.
Stick to the major brands and you will get better results (Panasonic, KeepPower, EVVA, Ultrafire (original with hologram)).

Chargers: look at the charge current per channel/battery...
Get one that can charge at 500mA minimum. Lower than that and charging is painfully long.
 
Netdoc, if your light fit 26650, use them, they have much higher energy contents, in term of max discharge current and mAh rating. There is no substitution for weight in Lion battery technology. 18650 is the best form factor in terms of capacity per weight, that is why people build canister light using 18650 instead of 26650 because for the fixed weight/size, 18650 wins.

I will NOT recommend those NitCore D4 chargers in general for two reasons:

1)they are slow charger. I think that D4 only charge at 500mA range. That means a typical 18650 with 2500mAh will take 5 hours to fully charge, way too slow. You can easily find 1500-2000mA charger these days.

2)If you use 26650, those D4 can only charge 2 26650 at a time using the outter slots. It just physically won't fit 4 26650. Even if you are willing to use 26650, a typical 4000mAh cell will take 8 hours to charge.

So not recommended at all.

Instead of buying cells from Amazon, I recommend Mountain Electronics for cells. They are battery specialist, all cells listed clear spec. All cells are good qualities.
 
https://www.shearwater.com/products/swift/

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