# 4x18650 Configurable Battery Adapter Design



## modamag (Feb 12, 2008)

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.


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## Nebula (Feb 12, 2008)

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


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## Barbarin (Feb 12, 2008)

Please, contact me by PM.

Javier


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## MorpheusT1 (Feb 12, 2008)

Sweet,


I would be in for some for sure.

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


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## JimH (Feb 12, 2008)




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## rizky_p (Feb 12, 2008)

I am interested depending on the price...


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## Bogus1 (Feb 12, 2008)

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.


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## modamag (Feb 12, 2008)

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.


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## JimH (Feb 12, 2008)

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.


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## modamag (Feb 12, 2008)

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:


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## LED Zeppelin (Feb 12, 2008)

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.


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## Aircraft800 (Feb 21, 2008)

I hope someone picks up the *Configurable Battery Adapter Design* for standard [email protected] 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.


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## modamag (Feb 21, 2008)

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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## Aircraft800 (Feb 21, 2008)

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.


 
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!


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## Action (Feb 22, 2008)

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?


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## modamag (Feb 22, 2008)

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


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## Action (Feb 22, 2008)

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?


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## modamag (Feb 22, 2008)

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.


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## Action (Feb 22, 2008)

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.



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.


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## cnjl3 (Feb 22, 2008)

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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## flex76italy (Feb 23, 2008)

Hi Jonathan,

i'm interested in this configurable battery adapter, put me in the list.

Thanks.


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## LuxLuthor (Feb 26, 2008)

Yeah, this will be nice for the quad wide 18650's....and with removable cells you don't really need to worry about balance tap charging as you do in a pack. Of course this will resurrect the age old multiple Li-Ion cell charging cradle shortage. 

Having the multi-level stacks as you show in last drawing is something that most would want to see.

I'm just thinking of ways that people could screw up the configuration/battery insertion....as shorting out the unprotected high current Emoli or A123 18650 cells will do some serious flash metal welding, and turn your Delrin into Silly Putty.

It may help by incorporating the Red/Black polarity colors with interchangeable holder terminal 2-3 mil stick-on replaceable round red & black labels with open center hole for contact. Maybe make a 3-4 mil recessed donut in Delrin so labels would not interfere with battery contact? I think this is important because if a user sets up these cells wrong, your entire holder will be toast.


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## mrsinbad (Feb 27, 2008)

Quad or triple wide, I very very interested.


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## LuxLuthor (Mar 5, 2008)

Gonna need extra boxes of popcorn. :thumbsup:  :thumbsup:


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## rolltide (Mar 6, 2008)

I would be interested in a few of these myself. Keep us posted.

Thanks


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## modamag (Mar 6, 2008)

You won't need too much popcorn Lux.
It takes ~ 30 mins to machine each retainer.
Couple more weekends I should have enough adapters for everyone. Yikes!

In all seriousness, I did take several of alot of everyone's recommendation into mind and try to come up with the best solution with minimal compromise.

1) SAFETY! It's alot of power so no moving part (such as spring or magnet) to reduce the risk of shortage.

2) SAFETY! Several visual cues were introduced to the adapter to help the user install their batteries properly. CNC engraving of P & N at the location that are fixed to that polarity. + and -, although are international standard were not used because the (-) might be hard to identify. I might even take a step further by punching out or laser cut color sticker to adhere to the retainer. Thanx Lux for remind me about this issue


I have tweaked as much the design as I can. Now is the hard part production. I got several quotes from small and large shops the ranges are from $40-80 just for the single stack alone  YIKES! If I add in the option for double stack that will increase the cost by another $15-$20. The BOM of the complete kit consist of 18 machined parts not including screws.

Parts needed to convert to double stack.
1x long #10 threaded rod
2x battery interface retainer to prevent rattling and remove the use of magnets
4x contact relay to go into the retainer.
4x optional 4-40 screws for the retainer.

*So the question boils down to economics.*

How many here would want.
1) single stack for $50 and do your own multiple stack conversion.
2) double stack for $70 with all the bell and whistle.

Give me your suggestion guys.


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## cnjl3 (Mar 6, 2008)

I want one quad-double stack for $70.
Will it come with the short rod for 4 cells 
and a longer rod for 8 cells?
Paypal locked and loaded.


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## modamag (Mar 6, 2008)

As a double stack it comes with everything so you can make.

4 in series
4 in series/parallel
8 in series
8 in series/parallel
4 & 8 parallel with slight modification.


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## LuxLuthor (Mar 7, 2008)

modamag said:


> As a double stack it comes with everything so you can make.
> 
> 4 in series
> 4 in series/parallel
> ...



Just cross-referencing with the two lights that this would go in. (Your Colossus & H22A's The Mammoth)

I'm sure I would get two of $70 packages....maybe 3. Thanks for working on this!:thumbsup:


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## karlthev (Mar 7, 2008)

I will be in for at least one double-stack.


Karl


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## adamlau (Mar 7, 2008)

Count me in for two packs minimum.


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## starfiretoo (Mar 7, 2008)

3 packs for Mammoth flashlight


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## kakster (Mar 7, 2008)

I'm in for 2 of the double stacks.


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## elnino (Mar 7, 2008)

I would be in for one quad double-stack adapter for use in the Mammoth.


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## H22A (Mar 8, 2008)

I'm in for one single stack and one double stack. Thanks.


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## Nebula (Mar 8, 2008)

Jonathan - I am in for two of the 2x4 holders, and if you are still considering the 3x version, I will take one (possibly two). Thanks. Kirk


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## flex76italy (Mar 8, 2008)

I'm still in, and as nebula said, if you consider the 3 stack version.


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## JimH (Mar 8, 2008)

Jonathan, put me down for 2 double stacks, possibly a third.


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## H22A (Mar 9, 2008)

Hi Jonathan,

Could you please let me know battery holder dimensions for both single and double stack? I want to make sure that Mammoth body works with your holders.

Thanks,
Setapong


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## modamag (Mar 11, 2008)

Setapong, the dimensions are as follows:

OD Max = 45.15mm (18.70mm cells)
Single Stack height = 85-90mm
Double Stack height = 159-164mm

Note:
1) Height variation is to accomodate cell length variation due to protection circuit and what not.
2) stack height does not include the nipple because it's recessed in the light switch or in the mating adapter when put end to end.


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## Lips (Mar 11, 2008)

.




1 X Double Stack for me please...




.


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## Action (Mar 11, 2008)

I'd be in for a double stack at least.


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## H22A (Mar 11, 2008)

modamag said:


> Setapong, the dimensions are as follows:
> 
> OD Max = 45.15mm (18.70mm cells)
> Single Stack height = 85-90mm
> ...




Thank you Jonathan for sharing information. The current Mammoth bore diameter is 45.00mm. Looks like I will have to enlarge it by another 2mm.


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## rolltide (Mar 12, 2008)

I would be in for 2 double stacks or one double stack and one triple stack.
Could we buy extra middle pieces so we could make mulitiple stacks beyond double stack?

Roll Tide


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## Rookwood (Mar 14, 2008)

I'm in for at least 1 holder.

Thanks!


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## mdocod (Mar 16, 2008)

I noticed in the OP that you are looking for someone to produce these.... I may be able to do that, however, I don't feel it would be ethical for me to use that exact design, as it very closely mimics FMs pack designs. But I could make something that would hold 4-8 or more 18650s in a quad-abreast configuration, series wired, if that is what is needed. I am currently prototyping 2 other pack sizes and complete mag-switch/socket replacement, so it would be awhile out before I could even start prototyping this design, but it doesn't sound like it would be too terribly difficult.

[edit in] I'm not sure if you are already rolling on it, but let me know if you think it'd be worth doing a run on these... I could probably offer the 4x18650 adapter for ~$30 give or take using a less sophisticated design.


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## 9x23 (Mar 18, 2008)

Modamag

I'm in for one of the double stacks.

Thank you

9x23


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## LuxLuthor (Mar 18, 2008)

How's the timeline looking for this?


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## modamag (Mar 19, 2008)

It's under way. Here's the first couple cell phone pics.
This should be completed by sometime next week.


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## rolltide (Mar 21, 2008)

This is very encouraging. Thanks for the pics.

Please put me in for a single as well as the double and triple. (All I really need in the single screw shaft, but I will happily pay for an entire single adapter. I just don't want to impose any further on the generosity you have shown making these available to those of us without the technical skill or equipment to make our own.) I don't know if you are going to be able to fill all the requests for this wonderful product, but even if you can't, thanks for sharing the great design. 

Thanks again.


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## mdocod (Mar 22, 2008)

is that UHMW you are prototyping on? Curious, as I have found that stuff to be great for quick and easy prototyping (it's very forgiving!)


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## X_Marine (Apr 2, 2008)

Thanks for heads up Lux, :wave:

I would like 2 dbls please sir..

Looks like great work Jonathan, many thanks. :thumbsup:

Thanks
X/BillyD..


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## MorpheusT1 (Apr 2, 2008)

Two $70 packages for me please


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## Rookwood (May 15, 2008)

Hi ModaMag -

Just checking to see how this project is going, and to let you know I'm still in for at least one.

Thanks


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## modamag (May 16, 2008)

Sorry guys for the late update. Everything was finished but work kept me occupied.

Anyway, the adapters are completed and is now available here.

These adapters will fit HA22 Mammoth, my Colossus, and even FM's elephant. One thing about the elephant is that for single stack you must use the standard short tailcap.

I've also knocked out another problem regarding the Lithium batteries. Although the 18650 lithium standard dimension is 18mm width and 65 height. As many of you already experience their height will range from 65.0 to 68 mm depending on the manufacturer, protection, etc. So I made a dummy 18650 cell that is adjustable height ranging from 65.0-70.0 mm depending on what cells you're using.


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## modamag (May 27, 2008)

Guys, a few of you should already have this in your hands by now.

Couple quick things.
1. I have designed out the parallel capability of the holder to keep cost down. If you're interested in this feature Let me know in this thread how many. I'll fab them for you.

2. As for the next minor revision of the adater I plan to add the following. If you have other features you want let me know and *I'll try*.

a) Retrofit negative plate to accept end-to-end adapter connection. There will also be a recess in the (-) plate's top side where a nylon sleeve will go. This is a safety issue just in case the rod retaining screw comes loose it will not short inside the (-) plate. For couple $$$, I believe this is well worth it.

b) Minor grooves on the bottom side of the positive plate. This is to reduce the overall weight but not affecting the current appearance.


Currrently, this adapter works perfectly with the Colossus, Mammoth and org. Elephant. If you guys need to make it work for the Elephant II let me know. It should be couple quick turning operations.

I will also post instructions of how to convert your adapter from Series -> Series/Parallel shortly. Stay Tuned!


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## Action (May 27, 2008)

modamag said:


> Guys, a few of you should already have this in your hands by now.
> 
> Couple quick things.
> 1. I have designed out the parallel capability of the holder to keep cost down. If you're interested in this feature Let me know in this thread how many. I'll fab them for you.



Glad you mentioned this. I'm really interested in the parallel capability, particularly in a 3x4x18650 setup so that I can get some really long runtimes. How do I sign up? I would also, at the same time, be interested in getting the middle adapter piece and a longer rod to do the 3x4x18650 setup with the holder.


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## LuxLuthor (May 28, 2008)

In case someone looks here, wanting to make a 12 cell setup, the threaded rods you need to fit are 10-32 and sell for $1.60 at Home Despot for a foot long.

Modamag, I would second the suggestion from someone in the sales thread to make the brass (+) end smaller diameter so there is a little more plastic edge to protect from shorting against inside tube when inserting/removing, and so it is no wider than bottom of Mag D Switch (1.334 inch). 

I know there is some annodizing which also helps, but I have two Elephant-I that have bottom of plastic switch flush with surrounding metal...which means as I twist the cap tight with tailcap spring pressure, the (+) end plate could rotate and press into metal, and short. 

I actually am concerned about this from a safety issue, especially with high current Emoli/A123 cells, and would even like to get new smaller diameter (+) replacement plates if possible _*at my cost*_. 

I saw that FM has the smaller size in his old Elephant-I, which is why I started looking inside the light to see why. Unfortunately after looking to see if any of FM's caps fit your theads, none of them do. Please think about this.


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## rolltide (May 28, 2008)

I really appreciate your attention to customer needs. 

I for one would really like both the all parallel option and the fit the Elephant II option. A few simple turning operations for you equal impossible for me.

I can send my two holders back for you to use to benchmark these changes and I will be glad to compensate you for your time.

Thanks for your consideration.


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## X_Marine (May 30, 2008)

Mine rolled in yesterday and look great.
Super job on these Jonathan, many thanks for all the work. :thumbsup:

X/BillyD..


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## Action (May 30, 2008)

I received a single one earlier in the week. Are double orders being shipped separately? The one that I have looks great!


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## karlthev (May 30, 2008)

Got the order--beautiful work!


Karl


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## cnjl3 (May 30, 2008)

I am very interested in your adapters parallel capability & I am looking forward to your instructions about our series/parallel options. I don't know about other users but my adapter will be used only with H22A's Mammoth -- so it goes without saying that I do have some time on my hands before I get to use your handy dandy adapter. I will leave my current 4/8/12 set up "as is" but it sounds like additional hardware will be required to run a plain jane 4 parallel set up. This is where I have a question about running cells in parallel. In a 4 cell parallel set up "all" cells are in parallel to each other. But jump up to 8 cells in a 2S4P set up and I have often wondered if maybe the pack also needs a central connector which does more than just keep each column of cells in series but also connects all four cells in parallel in the center. Is this an option? For the connecting rod - I was thinking that a center piece or plug of your thermal plastic threaded so that a user could then have the option to keep both ends of your end plates electrically isolated? Would this work?




modamag said:


> Guys, a few of you should already have this in your hands by now.
> 
> Couple quick things.
> 1. I have designed out the parallel capability of the holder to keep cost down. If you're interested in this feature Let me know in this thread how many. I'll fab them for you.
> ...


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## WarHawk-AVG (Dec 27, 2013)

Would this work as well?

http://dx.com/p/pannovo-b-c04-water-resistant-4-x-18650-battery-pack-case-for-bike-lamp-black-254957

Now just to figure out what kind of head it has on the end of the cable


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