View Full Version : Battery Pack Construction - Headway

22 October 2011, 1628
Working with Luke (http://www.mobilefabrications.com.au/)we have the battery holder design complete. Now to ship of the design for milling out of acetate. Within three weeks I should be starting the final assembly.

The design has 4 plates to hold the cylindrical headway cells to each other and the bike. The plates have bevelled holes to hold the batteries but allow the terminations to protrude for the electrical connections. The plates will be spaced apart by rods and the mounting holes will be reinforced by aluminium insets. Alloy brackets will be made to attach the plates to the existing engine mounts on the frame.
Battery Mount Design


The central plates are larger and fit within the sides of the current motorcycle frame. They are fare enough apart to mount a single width of batteries around the perimeter. The outer plates are used to terminate the double width section of cells that protrude from the centre of the frame. The inner plates have a standard hole that allows these cells to meet in the middle. The complete arrangement will fit beneath the original fairings providing a very clean look when complete.

This setup will hold 120 cells in a 24s5p arrangement giving a 72volt setup with 50ah, which should be enough for 70km or so on a charge.

Nuts & Volts
22 October 2011, 1707
This is awesome. I would be very interested in knowing how much your mount weighs once you get them machined. I think this will be one of the coolest Headway packs built. Ed's pack is super clean and low cost, and Travis's pack will be this cool when its done. I really think plastic is the best way to mount Headways. The Metal reinforcement for support is a great plan as well.

Oh yea I guess Zoom as a really cool polymer Headway pack too, just not as big as yours so you win :D

Looking forward to seeing how easy this is when install comes around. Good Luck

Oh do you have a model of the batteries mounted?? I am having trouble figuring out which plates the batteries are mounted between...

22 October 2011, 1721
I will get Luke to export the model along with a model of a cell. I can then lay them out and setup my connections. As soon as I get them I will put up a render of the fully populated pack.

Nuts & Volts
22 October 2011, 1814
Awesome! Looking forward to checking it out

22 October 2011, 2028
Whoa, that's almost identical to the battery holders I'm designing! Glad to see that the idea has some merit.
Great work, can't wait to see pictures of the finished parts. Really great work.

24 October 2011, 0815
looks great. A lot similiar to what I'm doing with mine. Keep us posted with pictures!

24 October 2011, 1428
Work is killing me at the moment. I will update as soon as I get the 3d renders and some time. Moon, frodus great minds, as they say. However I have copied the idea from others in the Endless Sphere forum http://endless-sphere.com/forums/viewtopic.php?f=14&t=12320

You kinda have to ignore the pushbike sizes and wooden boxes.. :)

04 November 2011, 1810
Ok waiting for Luke is taking too long. I have put together a very simple mockup in Google Sketchup showing how the batteries would fit in the plates.

You can see how the centre plates hold the double width batteries while allowing the termination of the single width. The out plates just allow for the termination of the double width cells.

Nuts & Volts
04 November 2011, 1828
Ok, yea now its perfectly clear. I was picturing 3 rows of batteries with empty space between them, but your bolting the ends right together which is an effective use of space and less resistance than a busbar.

This should be a very interesting pack, excited to see it power the colossus soon!

23 November 2011, 1200
hi splinteroz

looks smart to bolt them together!
do you want to use a onboard bms ? when i build my 26S4P pack some cells died in the first 10 runs .i checked every single cell (off 104) with a voltmeter and get them on level with a rc charger. after 20 runs the batterie was totally balanced. i use a overvoltage detection only on charge. in a dirtbike a onboard bms doesnt make sense but when you got enough room keep in mind! now i got about 50 charges on the pack - hope to get another 1500 :)

23 November 2011, 1258
You may find out that these batteries are not all the same length.

I had used plates before, but had to use buss bars due to the slight differences in sizes.
I am using the 3/4 " x 1/8 bars as they seem big enough for 450 amps (not even a hint of resistance issues)
and it is fairly light in weight. The "Jumper" bars are the standard headway buss bar.


23 November 2011, 2354
Ed, nice pack... I am going to have to create the bus bars lots of cutting there for me to do.

ronny, I am going to use a miniBMS (http://minibms.mybigcommerce.com/products/MiniBMS-16-cell-Master-Board.html) from CleanPowerAuto. One 16 cell slave board and one 8 cell partial master.
Now I am planning on doing the RC charger cycles you suggest for the first few cycles.

I should have more info in a day or so... I have been a jury member for a criminal trial over the last two weeks and I have done little else.

24 November 2011, 0451
Ed, nice pack...


24 November 2011, 0531
:cool: I shocked Ted!!!

24 November 2011, 0606

Glad you did not say....Nice Rack.....

That pack is one of two in the Cafe racer....fun stuff!

09 December 2011, 1357
Hey Splinter, can you give more info about the material itself. You say acetate in your original post, but that could mean a couple of different things. What tools did your fab use to mill it?

09 December 2011, 1403
Ok after weeks of work and jury duty I have finally got to the next step....

The battery mounting plates have arrived and I will be constructing the pack over the weekend.
Just to show how this will mount up I took some photos today...
http://farm8.staticflickr.com/7026/6479386725_46852623bf.jpg (http://www.flickr.com/photos/splinter/6479386725/)
Battery Mounts (http://www.flickr.com/photos/splinter/6479386725/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7141/6479388677_e7a0d28d3d.jpg (http://www.flickr.com/photos/splinter/6479388677/)
Battery Mounts (http://www.flickr.com/photos/splinter/6479388677/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7027/6479373081_b962e9be31.jpg (http://www.flickr.com/photos/splinter/6479373081/)
Battery Mounts (http://www.flickr.com/photos/splinter/6479373081/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7161/6479391827_822ed07b29.jpg (http://www.flickr.com/photos/splinter/6479391827/)
Battery Mounts (http://www.flickr.com/photos/splinter/6479391827/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

That should give you an idea on how the pack goes together and how it will mount up.

As for the material I will get that info today. Luke worked with the plastic suppliers to figure out the strongest, best weather and chemical resistance. So far he has just referred to it as Acetyl. It was milled by a local company that seems to have used a fairly standard CNC with a rotating cutter. There is sum "judder" marks on the inside of the holes where Luke believes the mill speed may have been set a little fast.

09 December 2011, 1935
OK I was wrong about the material. Luke first talked to the material suppliers about it and they were talking Acetyl. What they settled on however is Polyethylene (High-density polyethylene I believe). I will get the invoice from the guys next week and confirm. They were supplied the weight of the cells and the number of mounting points and this was the recommedation.

All four plates weight 3.6kg each plate is 10mm thick.

09 December 2011, 2042
This looks frickin awesome! Great work man.....

I was gonna say.... It looks like Polyethylene. That's exactly what I bought (I bought UHMW, ultra high molecular weight poly ethylene). Got a 4'x 8' black sheet of it.... and was going to mill it out similarly to you. Just waiting on some machine time from my buddy.

It's great stuff, cuts easy, but it's strong, and a little flexible so it's forgiving. The white looks nice, but it gets a little dingy. I'd dye it if you have time and really get a custom look.


09 December 2011, 2052
When you say dye it can I do that after the milling or is that something that has to be done in the original process?
Thx by the way... I am so happy with the look so far.

I am going to have to cover the connecter bars on the ends and was thinking of lexen or plexyglass so see through but finger proof. Any ideas

09 December 2011, 2221
I have had good results dying plastic with Rit dye. I'm not sure if it will work with yours but it works very well with nylons. You soak the finished part until it is as saturated as you desire.

10 December 2011, 0727
Polycarbonate takes Rit dye well, too.

10 December 2011, 0927
UHMW is not going to take a water based dye, since it doesn't absorb water like Nylon & Polycarbonate (Hygroscopic Polymers for all the young Mechanical Engineers out there).

The white does look awesome, nice work Splinter. As long as the material is UV stabilized (additive in good quality UHMW) it should look fine for a long time. Without a UV stabilizer, it will turn yellow with exposure to sunlight. At work, we use UHMW for a lot of production fixtures in the factory - tough stuff.

10 December 2011, 1336
They assured me it was UV stabilized, and is looks like they might stay white. :)

10 December 2011, 1708
There are adhesion promoters for paints formulated for use with low surface energy plastics so you might be able to get that to work. It's also common to flame polish low surface energy plastics which oxidizes the surface and allows paints to stick. Since these parts are thicker and less prone to impacts and flexing, unlike motocross plastics or kayaks made of the same stuff, there should be less risk of paint popping off.

If food can stain UHMW HDPE cutting boards, there has to be some solution on the market to change the color of this stuff.

10 December 2011, 1917
BTW, I was googling around for dying polycarb with Rit, and found this thread: http://www.dgcoursereview.com/forums/showthread.php?t=38339

Looks like Rit has a new formula and won't work on polycarbonate anymore.

10 December 2011, 2222
Ok here is the plates in place... will be building the spacers etc early this week and wiring up the battery later this week...

http://farm8.staticflickr.com/7169/6490495851_dd4937bb6b.jpg (http://www.flickr.com/photos/splinter/6490495851/)
Battery Mount position (http://www.flickr.com/photos/splinter/6490495851/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7164/6490492701_40e8419001.jpg (http://www.flickr.com/photos/splinter/6490492701/)
Battery Mount position (http://www.flickr.com/photos/splinter/6490492701/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

10 December 2011, 2254
That's sweet. :)

11 December 2011, 0621
How are the inside connections being made? Are you using pieces of threaded rod with locknuts or ? Do you have any closeup pictures?

11 December 2011, 1447
Frank, I will have the plates home this week and I will get the better camera out and try to get some photos showing the plates in detail.
The plan for connecting the cells in the centre was to use grub screws... you know the kind that hold in keystock. I would thread that into one cell (-ve) with some locktite and then spin the other cell on.

However due to some forehead slapping moments we realized that the 15mm depth of the plates meant that they were not clearing the frame properly. So we are going to use threaded rod and a 30mm aluminium spacer until I get new outer plate machined with about 3 - 5mm off the outer edge so they clear the frame.

13 December 2011, 0723
Hello SplinterOz, I'm currently trying to fit my Headway pack in the best possible way.
One question, how do you connect the two batteries together, i mean you have to take out the screw from the battery end and the other screw from the other battery, but then how?

13 December 2011, 1518
As I said to Frank "The plan for connecting the cells in the centre was to use grub screws... you know the kind that hold in keystock. I would thread that into one cell (-ve) with some locktite and then spin the other cell on."
You have to make sure you don't crew the +ve terminal in tight as it then blocks the safety valve.

Have a look here on a long thread in EndlessSphere (http://endless-sphere.com/forums/viewtopic.php?p=208251#p208251) you can see the grub screws.

16 December 2011, 2159
Ok so I have the bike home with some threaded rod, bolt and spacers to work out the layout of all the components on the bike.

Here is a shot of the way the plates have been machined to hold the batteries in place.
http://farm8.staticflickr.com/7154/6524051407_0b29bf8839.jpg (http://www.flickr.com/photos/splinter/6524051407/)
Battery Mount Size Layout (http://www.flickr.com/photos/splinter/6524051407/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

Note the spacers so all the pressure is not on the batteries themselves.
http://farm8.staticflickr.com/7014/6524050051_41af6cd093.jpg (http://www.flickr.com/photos/splinter/6524050051/)
Battery Mount Size Layout (http://www.flickr.com/photos/splinter/6524050051/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

See they will mount straight through.
http://farm8.staticflickr.com/7168/6524048035_f73fe11d0f.jpg (http://www.flickr.com/photos/splinter/6524048035/)
Battery Mount Size Layout (http://www.flickr.com/photos/splinter/6524048035/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

Setup with all batteries in place so I can calculate and drawup the electrical connections.
http://farm8.staticflickr.com/7158/6524058455_eedb5553fd.jpg (http://www.flickr.com/photos/splinter/6524058455/)
Battery Mount Size Layout (http://www.flickr.com/photos/splinter/6524058455/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7002/6524053145_c1448f3026.jpg (http://www.flickr.com/photos/splinter/6524053145/)
Battery Mount Size Layout (http://www.flickr.com/photos/splinter/6524053145/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7145/6524055141_267714debe.jpg (http://www.flickr.com/photos/splinter/6524055141/)
Battery Mount Size Layout (http://www.flickr.com/photos/splinter/6524055141/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

Bike still feels light easy to move and lift of the stand etc....

17 December 2011, 0101
How do you actually mount the batteries into the motorcycle frame? Do you have to mount the plates into the moto frame first and then put the batteries into the plates? Or do you do something else where you can put the whole batteries + plates together first and then mount the whole thing into the moto frame last?

17 December 2011, 0120
Ok so what I do outside the bike is place the centre batteries into the two centre plates and bolt those together. I then feed one side of the double width from one side with little grub screws already attached, place the conducting plate onto the battery ends. These batteries are pushed as far though as possible.
Once done I can lower or raise the assembly into the bike from the top or bottom (with the motor removed). These centre plates are then mounted to the frame using the original engine mount points.

The second batteries of the double width set is then slid in and screwed onto the grub screws. The outer plates are then put into place and the pack pulled together on the rods. When I do the final construction I will tack step by step photos... :)

17 December 2011, 0502
Dangerously, brilliantly, criminally insane. Goodness gracious. You should be chained up somewhere before someone gets hurt.

<iframe width="640" height="360" src="http://www.youtube.com/embed/9TbFcFohbs4" frameborder="0" allowfullscreen></iframe>

Seriously, man, this is amazing. Great, great stuff, and an inspiration.

17 December 2011, 0656
Seriously, man, this is amazing. Great, great stuff, and an inspiration.

+1! Can you post the final pack specs again, I must have missed it. Very clever!

17 December 2011, 0930
Do the spacers in the double-wide section fasten onto the middle two plates, to keep those cells from sliding side-to-side?

17 December 2011, 0930
Cool. I can't wait to see the pics! Thanks a bunch for the info. :)

17 December 2011, 1449
rabar10 do you mean the spacers that hold the plates apart, or the spacers I will need between the batteries? The plate spacers are just like pipes larger than the hole with a threaded rod through them to the outside of the plates. Nuts and washers then pull the plates together.

After putting the batteries in the pack yesterday I realize I will not be able to space the center batteries and still get the inner plates in the bike. So the outer plates will be machined so they will fit into the frame and overlapping about 10mm. This means the double width batteries will be right up against each other in the final construction.

(I will have to do the photos).

Now a question for you all. I am going to get the connector plates laser cut (if not too expensive) so I can join up all the cells. What material should I use for the headways? Copper? Aluminum? Brass?

Frank the pack will be 24S5P of the Headway 10ah cells. So around the 72 - 76 volt and 50ah. Total pack with cell terminations will be just under 50kg. 39kg of batteries 3.6 kg of plastic and several kg of screws, plates, rods etc.

17 December 2011, 2118
Dangerously, brilliantly, criminally insane. Goodness gracious. You should be chained up somewhere before someone gets hurt.
Seriously, man, this is amazing. Great, great stuff, and an inspiration.

Dude I am honoured. I can only say that Luke has made my scratchings on cardboard look like I know what I am doing. ;)

17 December 2011, 2124
Ok here is a few detail shots.

This one shows the rods and spacers used to hold the centre plates together. There is about 8 of these holding them together.
http://farm8.staticflickr.com/7171/6529113191_79ca40ccc5.jpg (http://www.flickr.com/photos/splinter/6529113191/)
Battery Install (http://www.flickr.com/photos/splinter/6529113191/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

Here is a few cells pushed in from the other side so they are just short of coming through. Imagine all the cells required pushed in like this and their connector plates on and the grub screws exposed.
http://farm8.staticflickr.com/7161/6529106075_2bdd16cdc8.jpg (http://www.flickr.com/photos/splinter/6529106075/)
Battery Install (http://www.flickr.com/photos/splinter/6529106075/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

and from the other side
http://farm8.staticflickr.com/7015/6529102135_268095606d.jpg (http://www.flickr.com/photos/splinter/6529102135/)
Battery Install (http://www.flickr.com/photos/splinter/6529102135/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

here you can see the batteries sticking out and the clearance I will have (not much).
http://farm8.staticflickr.com/7010/6529099301_156fa29978.jpg (http://www.flickr.com/photos/splinter/6529099301/)
Battery Install (http://www.flickr.com/photos/splinter/6529099301/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

With all the battery in like this from one side, all centre batteries inplace and all the rods in it should still slide in from the bottom of the bike.

I am away from mid next week for a week so there will only be a few updates.

01 January 2012, 0110
Ok i have a question reguarding wiring up my BMS. This is a centralized BMS that i need to put it in a box and expose he wiring. For the sensor leads from each parallel set I need 25 wires and of course they can be tiny. I was thinking of using a 25 pin D-Sub plug with the female end wired to the batteries and the male mounted to the bms case.

This would allow me to disconnect the BMS when required with little risk of short circuit.

The control wires I can terminate on the other side of the box, it will need to support more current, using a 8 pin din plug.

Question is can you see a problem with the plug arrangement?

01 January 2012, 0200
That setup seems ok except those DB25 connectors are usually hooked up to wires that i'm not sure i'd trust in a high vibration environment. Also, not sure if you need to worry about water, but keep in mind that those are connectors that are meant for inside use.

Just as a point of reference, I was considering using a similar arrangement, but then i decided i may want to reuse the per-cell BMS wiring for balance charging, so i upped my wire size for the sensor wires, and thus had to go with different connectors. I chose .062" (and some .093") Molex connectors instead (http://www.molex.com/molex/products/family?key=standard_062&channel=products&chanName=family&pageTitle=Introduction&parentKey=wire_to_wire_connectors)

For my control wires, my charger is off-bike, so i have the charging current wires and the charger BMS wires (2 x 12 gauge) and the 2 bms wires (2 x 20 gauge) running parallel to each other. The charging wires needed something that could handle 12amps continuous, so i went with anderson powerpole connectors. Since the BMS wires are parallel, i made a block of 4 powerpoles. Yes, the powerpoles are complete overkill for the BMS wires, but it made a nice block that's easy to plug in and remove.

01 January 2012, 0226
Good point about the balancing charge. I was really wanting to have sockets on the BMS housing rather than wire tails and connectors like the molex ones. So I am now looking at plug and sockect with at least 25 pins and about 2 amp power handling. As for charging only the on-off control due to high volts, the charge wires come from a fuse and contactor.

BTW it seems thatyou can get IP67 rated plugs and sockets in the DB25 setup.

01 January 2012, 0237
For a fairly small, high pin density connector that can handle up to 8A per pin, have a look at these Edac connectors : http://www.edac.net/product.html?cid=31. We use them at work for audio multicores.

01 January 2012, 0249
Hmm 2 amp would only handle the balance not the charge... I have a 6 amp balance charger so 6 amp is what i need. Note it seems that the d-sub crimps are fine for 5amp and the insulation for 500 amps. I think I might get the IP67 ones to test out... check the max cable size I can use.

04 January 2012, 0054
Ok an update with video :)


Now my big question, the cell connectors what should I get them cut from? Aluminum? Copper? Brass? and what thickness??

04 January 2012, 0310
Since Headway's are not all the same length, 1/8 inch (6.3mm) Aluminum would be my choice.
Copper will tarnish too quickly and brass is too hard. Aluminum will polish up nicely too. :)

If you are racing this then Copper would be an option although I have aluminum on the Cafe bike
and it works fine with no heat issues on the "high speed" runs.

04 January 2012, 0339
You are correct not a race bike.

6mm really that seems large. The standard headway connectors are 1mm thick and I know they are undersized but wow 6mm. If I go up that large I will have to buy a lot longer screws. ;)

04 January 2012, 0404
If I go up that large I will have to buy a lot longer screws. ;)

That is what I had to do, bigger bolts. The Headway straps easily rust so I went to aluminum with lock washers to keep things
from vibrating loose.

04 January 2012, 0520
Since Headway's are not all the same length, 1/8 inch (6.3mm) Aluminum would be my choice.
Copper will tarnish too quickly and brass is too hard. Aluminum will polish up nicely too. :)

MAN YOU HAD ME WORRIED. 1/8 inch is 3.1 mm!!!
That makes more sense. 6mm is the diameter of the screw to put these together.

So a 3mm aluminum bus bar plate... that sounds much more like what I expected. And the button screws I have bought already should be able to do that.

04 January 2012, 0548
For clarity: are you going to use solid plates to connect groups of cells, similar to the CAD pieces you show :) ? If so I would be aware of side loads on fasteners due to flexing, expansion, etc. Does anyone make a copper or aluminum mesh-type material?

04 January 2012, 1050
Just want to second EVcycle's recommendation of 3.1mm for the material thickness. Its what we use in a couple items at work that end up carrying 360 volts and 400+ amps. So should work perfectly for your application. Since you are using such large plates, definitely use isolating spacers between them like you are talking about using.

04 January 2012, 1606
Frank, yes solid plates I know of no flexible material that I could use.

Dicey hopefully I will be pulling no more than 300 amps for any length of time (1 min). I will price up laser cutting 3mm plates. I will now have to figure out how to build the isolating ridges.

04 January 2012, 1700

I am American, MM is foreign to me...except for all the Metric tools I own. :O
I was trying to convert it for you and got it wrong. Sorry!

YES 3.1MM will do you just fine. :)

04 January 2012, 2223
Ed you are forgiven.

05 January 2012, 0447
Thanks Dad. :):)

19 January 2012, 0132
Ok so I have the connectors designed and the outer plates slightly modified to fit better. I will be using 3mm Aluminum for the battery connectors and they will be all laser cut. This should all be ready for me by Wed next week ready for a long weekend.

You will see I have increased the gap between the plates...

http://farm8.staticflickr.com/7150/6724570007_d05b64aa42_z.jpg (http://www.flickr.com/photos/splinter/6724570007/)
Battery Holder Designs (http://www.flickr.com/photos/splinter/6724570007/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7020/6724569849_57dec4f61b_z.jpg (http://www.flickr.com/photos/splinter/6724569849/)
Battery Holder Designs (http://www.flickr.com/photos/splinter/6724569849/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

Note the green highlight is the outer battery holder plates.

19 January 2012, 0949
thats very awesome designing there Splinter - it really looks like something you should patent and produce...

19 January 2012, 1705
Allen thanks for the compliment. As for the patents and stuff, I am just standing on the shoulders of others. The holder and cell connection method has been used before the only unique thing I have is the shape for my model of bike.

06 February 2012, 0406
My God has this taken a long time. So today I finally got most of the plates to connect the batteries together. I made one mistake, Luke made another and the laser cutting place made a third so we are down a few plates. However we have enough to test assemble the pack outside the bike and get all the measurements for all the spacer rods etc.

http://farm8.staticflickr.com/7005/6828917395_01f61da03f_z.jpg (http://www.flickr.com/photos/splinter/6828917395/)
Battery test construction (http://www.flickr.com/photos/splinter/6828917395/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7164/6828923195_2e87e55a05_z.jpg (http://www.flickr.com/photos/splinter/6828923195/)
Battery test construction (http://www.flickr.com/photos/splinter/6828923195/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7021/6828927247_63278b339a_z.jpg (http://www.flickr.com/photos/splinter/6828927247/)
Battery test construction (http://www.flickr.com/photos/splinter/6828927247/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7160/6828930517_5d44a3cda3_z.jpg (http://www.flickr.com/photos/splinter/6828930517/)
Battery test construction (http://www.flickr.com/photos/splinter/6828930517/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

http://farm8.staticflickr.com/7013/6828924493_9294bc7b69_z.jpg (http://www.flickr.com/photos/splinter/6828924493/)
Battery test construction (http://www.flickr.com/photos/splinter/6828924493/) by Splinter (http://www.flickr.com/people/splinter/), on Flickr

Last one shows the spacing between the 3mm aluminum plate and the plastic.

24 May 2012, 1943
SplinterOz (and Moon),

I am plotting a similar pack for my build (http://www.elmoto.net/showthread.php?2312-Suzuki-Savage-RYCA-RS1-ecafe/page2) and wanted to ask where you two would say I should be on the spacing between cells when using High-density polyethylene. I will be doing a single layer, so I think I'd like to do the inset that holds cells within the poly sheet. I am using 15 ah hw's, 40mm diam.

Thanks for the awesome builds and the help.