I have a number of flashlights that use 3c batteries. I was thinking about making an adapter to run 2 18650. But I started to think there must be a bunch of people out there sick of using NiMH C batteries or what I do AA converters. Has anyone ever had experience getting a custom cell made. I am thinking a 26150 (150mm) would be nice. If its even possible what would the minimum run size be? 1000? 10,000?
Am I just wasting my time thinking about this?
You might have problems with the voltages with your proposed setups.
Whatever size battery fits in the tube 26650—21700 etc then make a dummy spacer out of aluminum for the rest of the tube —- maybe your light will be able to run on 4.2v —otherwise just buy some new lights
@scotty321 I am thinking about running 2 18650 in parallel. the flashlight run fine on 3AA NiMH batteries in series.
@chops728 I have lots and lots of flashlights, and lots and lots of 18650 recycled cells lying around. I don’t mind cramming 2 18650 in parallel, but here are a lot of people in the world that may have a lot of devices running on 3C cells. Just wondering if anyone knew how likely it would be to get a set of custom cells made to sell retail. Not really to make money just to solve a problem. I would think a 26150 battery would hold a lot of power and would run 3cell batteries for a long long time.
A protected 3.6V 25150 size would work, but you would need need to figure out a way to charge it and it would likely be very expensive even with a large minimum order, assuming that you could find anyone who would be interested in making them at all.
A single protected 21700 5000 mA cell in an adapter will give you a little better run time and the same Voltage as 3 full capacity NiMH C cells without all of the weight and having to charge 3 cells instead of just one.
so you can cram 2 / 18650 in a tube that takes C batteries —- what kind of lights are you talking about —- Hypothetically if you could get 26150 cells made —In series they would total 11.1v / 12.8v —— way above 3 C batteries in series 4.5v
C batteries are 26x50mm in size, right?
The easiest way would be a 6800mAh 26800 battery and an spacer, but you are loosing half the space.
Actually closer to 25x50 mm - 26 mm is too wide for most C cell lights.
I’m a bit confused. 2 18650 is way shorter then 3C cells… When I say a 26150 I am meaning 26mmX150mm which doesn’t exist. I understand the naming convention is to add a 0 but If I would make the cell I would call it a 26150 because why add a 0 and confuse people. And yes I would rather say 1865 cell then 18650.
I do agree that a 25mm cell might be better incase some flash lights are a bit small. Maybe someday there will be a 25150, I guess by then few people will have anything that runs with 3C in series.
Thanks for everyone input. I have the 18650 cells so I will just cram 2 in with a small spacer and wire them in parallel. I guess if I want to get fancy I could put them in series and use a buck converter.
I would say look into what the Maglite people are doing. Forum member “vestureofblood” does a lot of Maglite stuff, and sells this adapter on his site LINK . I had also seen this adapter on ebay LINK .
TY for the links. that 2nd link is more like it. I just want to have 2 18650 in parallel. Keep the cell cooler get more run time. I will likely just hack something together with a couple wires and some 3/4” pex tubing as a sleeve.
Getting custom cells made is crazy. Using your 18650’s in parallel pairs is fine, but to really wire them up properly you want a cell welder, the cheap ones on Banggood appear to be junk, and good ones are on the expensive side for something like this.