"Forming" Custom Size Battery Cases

Batteries, Chargers, and Battery Management Systems.
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DrkAngel
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"Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 22, 2013 10:04 am

Every since I noticed rectangular shaped PVC water drain downspouts I have "enjoyed" the thought of using PVC as battery pack containment shells.
PVC pipe comes in various sizes, shapes and thicknesses.
Pipe, rectangular gutter downspouts, square fence posts, flat sheets etc.

PVC can be bonded with PVC primer and cement or "melted" together.

Durable and waterproof, if shaped to desired form and dimensions, might be the perfect material!
A heat box (oven) must be constructed. (Don't let your wife or mother catch you using her oven!)
An old electric skillet w/thermostat, heat gun, possibly even a hair dryer might work as heat source.
Also important, as determined by sheet plastic forming experiments, is a circulation fan to evenly spread heat.
Using 2 internal forms with spreading capability is the simplest method of attaining desired shape and size.
External shaping, as in form below, might be required to attain precise shape. (See example below)

"As for building a pack ...
I have toyed with the idea of reforming PVC pipe.
Heating to the point of softness then inserting a desired shape-form, then allowing to cool, then removing "form".
In the case of your pack:
a house shaped rod and a box shaped rod
Place both inside pipe
heat till soft
with wedges, spread house and box to stretch-form to desired size.

Image"

Warning! PVC (Polyvinyl Chloride), like most "plastics", can produce harmful fumes if overheated or burnt!
Last edited by DrkAngel on Sep 26, 2013 8:16 am, edited 6 times in total.
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DrkAngel
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Re: "Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 22, 2013 10:36 am

Warning! PVC (Polyvinyl Chloride), like most "plastics", can produce harmful fumes if overheated or burnt!

Forming temperatures are below the temperature of boiling water ~175F 80C .
A double boiler method might be the safest.
Use rubber gloves and watch for hot steam, you can still get burned, even at these relatively low temperatures!
175F is much hotter than will come out of your home hot water tank or your coffee pot.

A hot pan "bath" might work?

Finish-additional forming might require heatlamp or heatgun assist.
Last edited by DrkAngel on Sep 24, 2013 9:08 am, edited 1 time in total.
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Re: "Forming" Custom Size Battery Cases

Post by xenodius » Sep 22, 2013 10:43 am

Why not use ABS sheets "welded" with acetone, sanded at the edges and sprayed to protect from uv damage? A'la patrickza?

I still have a pound of raw, powdered PVC from my firework days, good chlorine donor and very effective binding agent even at 2 percent by weight. I think I paid $4. You could make a lacquer (probably?) and layer it to the right thickness.

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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 22, 2013 4:01 pm

It doesn't have to be PVC pipe, you can directly buy PVC sheet in ebay and it's easier to create custom size out of it.

I've tried polycarbonate heat forming with my heat gun before and it was quite easy to do.

Problem was to have the exact desired shape. Ideally I would need some mold then heat the plastic, but I don't know what material I could use to mold.


But I've found plastic sheet a bit expensive in france. Something like 20USD/square meter of 3mm thick PVC sheet. Not sure how to find it cheaper.
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 23, 2013 12:13 am

Hey I've found this made of PVC in France:
http://www.ebay.fr/itm/PLAQUE-PANNEAU-P ... 2a315dba5f

2 euro each for 65*45cm. looks like a good deal?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: "Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 23, 2013 7:25 am

PVC sheets 3mm, 4mm, 5mm, 8mm available.
68"x24"x3/16" <$20
5mm PVC Yoga Mats

Of unknown density, will try to find comparable at local department stores.
A little learning is a dangerous thing;
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There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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cwah
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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 23, 2013 7:27 am

I think it's better to have hard case than soft pvc matt case for battery, isn't it?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: "Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 23, 2013 7:58 am

cwah wrote:I think it's better to have hard case than soft pvc matt case for battery, isn't it?
Yeah, not sure of mat density.
PVC? sheets, sold as snow sleds-sliders sounds about right.
A little learning is a dangerous thing;
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There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: "Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 26, 2013 7:17 am

cwah wrote:Seller just told me it's PVC FOAM. He said it's 5mm thick so it's quite strong and rigid. Able to handle 50kg weight without breaking.

I'm a bit dubious because it's still foam... But he has good price at 3.5USD for an A2 sheet.

Can I use it for battery box?
I considered Yoga mats, at up to 8mm thickness. Presumably these are also some type of lower density "foam".
Fortunately, PVC has a very low working-melting temperature.
After proper shape attained, brief passes with a heat gun should melt the surface, momentarily, creating a very hard dense shell! ... ? Smooth, well regulated passes, should produce a nicely textured, strong, durable shell, with a tough though softer (more resiliant) inner layer.
Best results might be from "shelling" outer and inner surfaces creating rigid but very strong construction!

High dryer might be sufficient. slightly regulating input air will increase output temperature.

Project might require support while being heated, to prevent sagging.
"Reinforcing" with flat higher temperature flat plastic squares might work nicely!

Practice will perfect methods. An artistic bent recommended.

Remember! Leave a way to access cells later. Repair-replacement etc.
Last edited by DrkAngel on Sep 26, 2013 11:03 am, edited 2 times in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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cwah
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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 26, 2013 7:28 am

So I can buy from him no problem? I can invest my money to buy plenty of sheets for now and the future?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: "Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 26, 2013 7:47 am

cwah wrote:So I can buy from him no problem? I can invest my money to buy plenty of sheets for now and the future?
Get some samples to play with first?
These are experimental methods I'm recommending and modifying is almost certainly required.

PVC is recommended due to "low temperature" workability, durability.
Using "foam" PVC and "shelling" it should provide increased rigidity while reducing cold weather cracking possibility.

OH! PVC "cement" can come in colors! Be aware, clear, amber, white, purple glue seams will show!

AND ... PVC primer and cement are flammable! Do not heat until well set and cured!
Krylon@ makes a plastic capable spray paint ... covers a multitude of mistakes.
Last edited by DrkAngel on Sep 26, 2013 11:06 am, edited 1 time in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Index - Homemade Battery Packs - Updated - November 2015

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Re: "Forming" Custom Size Battery Cases

Post by friendly1uk » Sep 26, 2013 9:17 am

I have used a heat gun a few times, but it has always led to cracking in hostile environments. Pvc drys out over time, and it happened quicker when baked.
I have some solid pvc ducting to use. Same kind of thing, but I'm just bricking up my loose components within it for neatness. I wouldn't use it for structural duties. Fence posts though someone said. That is different. There are enough sizes to get the right one, even if it means chopping and gluing.
bmsbattery sent me broken and incorrect stuff, and won't even talk to me about it.

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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 26, 2013 9:56 am

What do you use for structural duty then?

I was thinking to only use the 5mm pvc foam sheets, but what would you advise?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: "Forming" Custom Size Battery Cases

Post by cal3thousand » Sep 26, 2013 11:50 am

xenodius wrote:Why not use ABS sheets "welded" with acetone, sanded at the edges and sprayed to protect from uv damage? A'la patrickza?

I still have a pound of raw, powdered PVC from my firework days, good chlorine donor and very effective binding agent even at 2 percent by weight. I think I paid $4. You could make a lacquer (probably?) and layer it to the right thickness.
ABS is great stuff. Easy to work with and strong enough.
Get a Cycle Analyst and a Multimeter, you're still a noob if you don't have at least one of each.

Planning on posting questions or buying anything on this site? Put up your country (at minimum) on your profile. This is a worldwide forum and we haven't reached clairvoyance.

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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 26, 2013 12:47 pm

but ABS sheet aren't cheap? see pricing here:
http://www.ebay.fr/itm/3mm-Black-ABS-Pi ... 3a711365c6
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: "Forming" Custom Size Battery Cases

Post by xenodius » Sep 26, 2013 6:13 pm


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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 26, 2013 6:20 pm

in europe it's much more expensive:
http://www.ebay.co.uk/sch/i.html?_sacat ... et&_sop=15
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Re: "Forming" Custom Size Battery Cases

Post by cal3thousand » Sep 26, 2013 6:25 pm

It's not cheap... but it is affordable when you buy a giant sheet at a time.

I got some 1/4" stuff (twice as thick as the 3mm) for $40 shipped and it measured 48" by 16"

Also got 1/8" (about 3mm) for $30 shipped and it measured 48" by 24"


Here's a 500mm by 500mm (3mm thick) for 27.50 GBP shipped:

http://www.ebay.co.uk/itm/1-x-Black-ABS ... 35c7bb532f
Last edited by cal3thousand on Sep 26, 2013 6:29 pm, edited 1 time in total.
Get a Cycle Analyst and a Multimeter, you're still a noob if you don't have at least one of each.

Planning on posting questions or buying anything on this site? Put up your country (at minimum) on your profile. This is a worldwide forum and we haven't reached clairvoyance.

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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 26, 2013 6:26 pm

it's affordable in US

not in europe!!
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Re: "Forming" Custom Size Battery Cases

Post by cal3thousand » Sep 26, 2013 6:30 pm

cwah wrote:it's affordable in US

not in europe!!
Is 27.50 GBP better for 500mm square of 3mm thick?

Not as cheap as the PVC, but much easier to work with. Maybe 1.5mm would still have strength equivalent to the PVC.
Get a Cycle Analyst and a Multimeter, you're still a noob if you don't have at least one of each.

Planning on posting questions or buying anything on this site? Put up your country (at minimum) on your profile. This is a worldwide forum and we haven't reached clairvoyance.

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Re: "Forming" Custom Size Battery Cases

Post by cwah » Sep 26, 2013 6:56 pm

Why is it easier to work with than PVC? PVC can be bent easily too
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Re: "Forming" Custom Size Battery Cases

Post by DrkAngel » Sep 26, 2013 7:34 pm

Various melting points of different types of plastic:

The melting point of HDPE (High Density Polyethelyne) is about 130 ºC
The melting point of LDPE (Low Density Polyethelyne) is about 110 ºC
The melting point of PET (Polyethylene terphthalate) is about 250—260 ºC - Danger - too hot - 500 ºF
The melting point of PP (Polypropylene) is about 160—170 ºC
The melting point of PS (Polystyrene) is about 70—115 ºC
The melting point of PVC (Polyvinyl Chloride) is about 75—90 ºC
Source:
http://www.goedjn.com/essays/botplas.html

The melting point of PMMA (poly(methyl methacrylate)) - Plexiglas is about 180 ºC 356 °F

ABS (Acrylonitrile butadiene styrene) (chemical formula (C8H8)x· (C4H6)y·(C3H3N)z) is a common thermoplastic. Its glass transition temperature is approximately 105 °C (221 °F).[1] ABS is amorphous and therefore has no true melting point.

POLYCARBONATE (Makrolon®, Lexan®, Zelux®) Melting point : 300 - 310° F (149 - 155° C)

Forming, or shaping temperatures, are several degrees cooler.
Last edited by DrkAngel on Sep 29, 2013 10:03 am, edited 1 time in total.
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There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: "Forming" Custom Size Battery Cases

Post by jonescg » Sep 26, 2013 8:00 pm

If you have access to some good fabrication tools and machines, any of these plastics will make a good battery for your e-bike. The critical thing is that your battery pack be SNUG inside the hard, protective case. Any amount of fretting or movement inside the enclosure will damage the cells.

I can't see why some standard sizes couldn't be made to suit the various cells we have available and vary one or two dimensions according to their capacity.

Oh, polycarbonate can be machined and takes a thread really well. You can glue it with dichloromethane too.

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"Simple" Electric Oven

Post by DrkAngel » Sep 27, 2013 7:44 am

Moved to top of page 2 for easier accessibility.

See - Simple oven and basic procedure
Last edited by DrkAngel on Sep 27, 2013 9:12 am, edited 1 time in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

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Re: "Forming" Custom Size Battery Cases

Post by spinningmagnets » Sep 27, 2013 9:03 am

Now this info (the two posts above) are really useful. Thanks for finding out all of this and posting it.

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