Batteries: 18650 or 26650? Low or High discharge?

[The Chairman]

I have two Piglets (Hog back up light), two way awesome video lights from DRIS and a SCUBALAMP PV52 which all use rechargeable batteries. All but the DRIS lights use the 18650, which are easy to get. I have put the 18650 into one of the DRIS lights and it works, but there's all that room around the battery. I just don't like that.

So, what's the point of this thread? There's just so many choices here. How do you make any sense of it? High or low discharge? How big of a battery? I finally got a smart charger which has Identified a dead battery already causing my PV52 to act all wonky. Here's my current set up, but I am willing to change...

Amazon.com: 12 Pack of 3.7V 5000mAH 18650 Rechargeable Li-ion Battery Yellow: Electronics

Amazon.com: Nitecore D4 smart Charger with LCD display For Li-ion, IMR, LiFePO4 26650 22650 18650 17670 18490 17500 18350 16340 RCR123 14500 10440 Ni-MH And Ni-Cd AA AAA AAAA C Rechargeable Batteries with 2 x EdisonBright AA to D type battery spacer/

What do you use? Why? What don't you like?

 

[gstrek]

I've got 2 dive lights that use 18650 batteries, or alternatively can use two CR123 batteries. The lights are from two different manufacturers that have their own 18650 battery and charger. In order to stay under warranty, you must use the vendor's 18650 battery.

From what I have found, 18650s are not as standaradized as are 'standard' batteries such as 'AA', 'C', 'AAA', etc. and many device manufacturers will 'rewrap' and add protective circuitry to an 18650. This can change the length slightly.

18650s are used for many things from laptop battery packs to 'vapes' to Tesla cars (where they use several thousand of them). There are also different internal chemistries among batteries. Some have positive buttons, others don't. Some have protective circuits, others don't.

There is a lot of info if you google 18650 battery. Here is a short synopsis with several links:
Best 18650 Battery
I decided to use the light manufacturer's battery for my lights to maintain the warranty. I wasn't going to risk an expensive light to save a few bucks on bulk batteries.

Gary

 

[The Chairman]

Great resource, Gary. Thanks!

I think the best thing anyone can do BEFORE they dive, is to check the voltage of the cell. The Nitcore d4 charger makes it easy to do, but really, any DVOM will do this job nicely. You wouldn't dive a tank without checking the pressure before you splash, so don't dive blind: check!

 

[The Chairman]

Interesting note... I just found that 3/4 PVC water pipe slips into the DRIS flashlights perfectly. I cut it about a 1/4 inch shorter than the battery, but it could have been about 3/4" longer to make it 3" for this particular light. I think I'll do that and make sure it lights.

Yes, it works fine at 3 inches long. Now to see how long it burns on the newly battery.

Turned on and put in a glass of water at 8:50 EST.

 

[tbone1004]

same charger, but I only buy Panasonic cells. I'll continue to use the ones that came with them until they die, but all replacements are the high end cells they use in the DPV and canister light packs etc. Hard to find and not cheap, but much better than the cheap chinese ones. Problem is sifting thru all of the junk. We need Amazon basics to come out with them soon to make life easy.

For lights they are low discharge btw.

 

[The Chairman]

Wow... it's only 9:25 and there's a HUGE dimming effect. That sucks!

 

[tbone1004]

you have to remember that the 26650's have almost twice the juice of an 18650, so it's not that surprising that you'd see big dimming effects. This is the problem with these lights that are being driven not much higher than their required voltage. The Cree XML's are nominal 3v a bit higher than that for most of the lights I think, and the battery is at 3.7, so there isn't a lot of buffer for voltage drop before dimming occurs since the electronics eat some voltage in efficiency losses etc.

 

[The Chairman]

It's def a much bigger battery. Here I was hoping for a one battery solution. I'm guessing not at this point.

 

[The Chairman]

Update... yeah, the 18650s only last about a half hour before they dim noticeably.

 

[tbone1004]

what were the 26650's doing?