4x18650 Configurable Battery Adapter Design

Friends, you probably have seen my The "Elephant" and the "Mouse" thread. I cram 4x 18650 into an FM fatbody (aka Elephant) using a custom 4S1P power pack. It was a PITA to make the pack. I had to provide individual leads for cell balancing. It was a good thing cause my Triton couldn't charge 4S

Anyhow, I'm in a quest to make a battery adapter that will allow the user an easy method of disassembly and an easy way to reconfigure the adapter to his/her own individual need.

Myself being an LED guy, typically will need high voltage and does not care much about current since it's relatively low (<3A). But my friend JimH on the other hand needed both high voltage and current with the special need of dropping one or two cell easily.

(Why would you ask I help JimH? Well to keep the game incan vs LED fair, even though the use of OSRAM have pretty much increased the race margin by 1500 lumens. Anyhow this lead to another long time debate and struggle to be told in another thread.)

So here's my plan. Create a battery adapter that will have <0.5 Ohms resistance from anode to cathode and with the versatility of making the following configurations.

3S1P + 1x dummy ==> 11.1V
4S1P ==> 14.8V
2S2P ==> 7.4V
3S2P + 2x dummy ==> 11.1V
4S2P ==> 14.8V
5S1P + 3x dummy ==> 18.5V
6S1P + 2x dummy ==> 22.2V
7S1P + 1x dummy ==> 25.9V
8S1P ==> 29.6V

Plus any other configuration you can think of with the use of dummy cells.

Note 1: 18650 are used for maximum power density and discharge capacity.
Note 2: "S" indicate # of cells in series while "P" indicate # of cells in parallel.

Here's a 3 yrs old design revised to accommodate the need. Any recommendation to improved upon the design are more than welcome.


I need 3x units. One for myself, two for JimH. Anyone interested in producing these? I'm too lazy these days to make anything, but I'll if I have to.

Very nice work, Jonathan. I am interested in one or two of these if someone decides to make them available. Kirk

EDIT: Jonathan - sorry I forgot to ask.

1) Will these holders be for use with only 18650s?

2) If so, how will you accommodate more than 4 cells? Will the holders have an interchangeable center rod to take full advantage of the interchangeable design? If not, do you envision stacking two holders for the 5 through 8 cell configurations? It seems that the interchangeable center rod would be the most economical, but not the most robust for long term use. Thanks.

Kirk

Please, contact me by PM.

Javier

Sweet,


I would be in for some for sure.

Maybe 3 sets + depending on timing and Flashlight qty when finished

I am interested depending on the price...

Hi Jonathan,

We have an interest thread going for 3x 18650 tubes and are looking for possible battery carrier designs. If we could integrate this layout into our design (pending interest) it would make sense to build some of these as well I'd imagine.

I'm hoping to price is low because otherwise it'll defeat the entire purpose. Something < $40-50 depending on quantity. There are couple pieces that require multiple machine operation (expensive) but I'm trying to design them out.

Nebula: Target is 18650 due to it's availability and power. However you can easily use a 17650 in place if you so choose. The center rod determine the stack size (4 cells, 8 cells, 12 cells). That's why they are so "beefy".

Barbarin: Javier, I'll send email. I hate PMs.

Bogus1: for the 3xN 18650 configuration it's very easy because there is no need to transfer the (+) contact from the bottom to top. To make them reconfigurable (series/parallel, etc) is a little more challenging in such configuration. I did a design for 17500 which can easily be modify for 18650 usage.

Here's the CAD drawing. You're more than welcome to use it.

Another consideration, not all 18650's are the same diameter. The protection circuitry in a protected cell makes it slightly larger than a non-protected cell.

4 of AW's protected 18650 Li-ion batteries will fit in an elephant, albeit very snugly. Slight boring would be advised.

On the other hand 4 Makita 18650 emoli's will fit in an elephant easily. No protection, but also very much safer chemistry than Li-ion.

Jim you're absolutely right. The range of cell this holder can accomodate is 18.30mm or less. AW's cells are 18.2 +/- 0.05 IF you mis-align the vertical strip, they are also on the "fatter" side of the spectrum due to the thicker plastic casing and protection circuit.

I C you got the Emoli cells out :wicked:

Jonathan, nice design. I particularly like the reconfigurable contact strips for series or parallel operation with the same holder.

I'd be interested in 3 holders.

As Eric mentioned, if a similar design could be offerred along with the TnC D-Flex line, there would be universal appeal for incan or LED.

I hope someone picks up the Configurable Battery Adapter Design for standard M@gs also, that would give me plenty of options for power.

If you make the center rod a standard size, the user can cut and run a die down it to their liking, or use a simple thread rod.

Aircraft800, thank you for the input. I'll make the center rod standard 8-32 rod. 1/4-20 would be better but then it will have conflict with some future designs modification.

modamag said:

Aircraft800, thank you for the input. I'll make the center rod standard 8-32 rod. 1/4-20 would be better but then it will have conflict with some future designs modification.

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Cool, Even 10-32 should work and offer higher strength, but I'm not sure what your future plans are :naughty:.

I believe even the cheapest bolt cutter has 8-32 and 10-32, I just use a hacksaw with a nut installed, cut it, file it, and back it off the nut to clean up the threads. (for users who have no fancy tools).

Nice Work, I'll keep an eye on this one!

What is the anticipated timeframe for producing something like this? Is the anticipation that one could put 8x18650 cells into a single holder or combine holders? Is there an assumtion of using magnets between batteries with longer lengths? Is the holder going to be designed to fit inside the mammoth tube without modification using AW's protected 18650s?

Action: So many tough questions in such a short post.

1) 2-3 months time frame, currently the design is going thru final refinement then freezed for production
2) Yes, but that's a hokey solution. With 4 cells side by side you have no gap to prevent the cells from springing outward. You can guide it into the tube then it will work fine.
3) I might produce an interlink adapter piece depending on cost. But NO MAGNET in my design. Safety & liability that's why I didn't release this earlier.
4) Mammoth, w/o knowing how it's design I can't answer this question. It's up to the designer to make the body and extension to fit the battery holder, not the other way around.

Here's what I have in mind of expandability to accomodate 4/8/12 etc

Thanks so much! A far more complete reply than I anticipated.

Two more questions...

Have you been in communication with the Mammoth's creator regarding building this to fit?

Do you have a draft of the physical specifications of this holder when fully populated with AW's 18650s in the 4X18650 and the 8X18650 sizes?

1) No, tell you the truth, I didn't know the Mammoth exist until the begining of this week. I was working on my own Colossus body, utilizing this holder and a huge head.

2) Yes and no. AW's batteries varies in size so I have to design to accomodate the standard 65mm with tolerance of -1mm / +4mm.

modamag said:

2) Yes and no. AW's batteries varies in size so I have to design to accomodate the standard 65mm with tolerance of -1mm / +4mm.

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Can you provide some draft measurements (by design) of the holder with batteries in a 4X18650 and 8X18650 setups?

This would be really helpful for those thinking about the Mammoth and counting on a holder like this.

I am very interested in your multiple battery adapter. It would be sweet if it is compatible with the upcoming "Mammoth" body. But, even if it isnt - I am still interested because you mention you have your own body in the works. Any time frame on your body design?

modamag said:

1)I was working on my own Colossus body, utilizing this holder and a huge head.

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