Making my own battery pack

[DirtyGinge]

yea, they aren't as snappy as a sensored, but I guess if im going to hardwire, wont want to be undoing it too often

[Andrew]

Here's my plastic press moulding attempt so far....












There is still plenty to work out....  Sealing, opening and fitting being the main things...lol

[Bikemad]

Andrew, that looks very smart indeed, now I'm waiting to see the finished item mounted on the bike. 

It looks like you have used plywood for the outer part and laminated MDF for the inner plugs, but why are there two inner plugs?

I was expecting two outer frames that clamped securely together either side of the material being formed and one centre plug which could be pushed into the heated material from either side to create the two halves of your battery box.

Alan
 

[Andrew]

To create extra space in the frame container to hold 18ah (54v x 6  3ah packs)  the container will sit over the top tube frame of the bike as well as inside the frame triangle.  I will now have to make semi circle cuts at each end of the moulds so it snuggly fits over the top tube frame.

To do this will be a bit of a pain to get correct as the top tube of the frame is an oval shape.

I will try and get the exact shape by moulding some foamex strips around the top tube to get he exact shape needed before I cut into the ends of the mould, this will be the tricky bit to get right.

I am going to use some neoprene beading around the edge of one of the mould sides and some around the holes I have to make to go around the top tube of the frame. I will then need some kind of fastener, nut and bolt if necessary to bind the two halves together to make it water tight. I would rather use some kind of fastener/clip to secure the two sides together for easier access to the lipo packs for balancing but as you can probably tell I am making it all up as I progress

I have not found a suitable clip yet.  I need something like a jar clip fastener  like used to seal large kitchen jars.    If you have any ideas of what I can use please let me know.  I really need to get to a fastners producer, I believe there is a place in Cardiff I can go to with my problem. 

This is a long term project so don't expect any finished results soon.   I really am making it up as I progress.  It has not really cost me anything but time so far as I used spare pieces of mdf  and got the foamex from school as an experimental project.

I wish I could add some diagrams but don't have the means to do that on my ipad.


I am a bodger rather than an engineer but I love  problem solving in situations like this.

[Andrew]

Andrew, that looks very smart indeed, now I'm waiting to see the finished item mounted on the bike. 

It looks like you have used plywood for the outer part and laminated MDF for the inner plugs, but why are there two inner plugs

Alan

I made one big plug and then cut it in half.  The width of the mould when put together is around 81mm which is the size of the lipo bricks I am using, so I get a tight fit to stop the packs jiggling around. No doubt foam and may be shelves will be needed to pack in as well.  If I made one deep mould rather than two the plastic would have to be over stretched, dothing both sides at the same time would have been impossible.   I literally pressed the outer frame over the plug. I had to do several tries as I had to estimate how much gap to leave around the outer frame. 10-12mm did it. The foamex has a memory so when reheated it goes back to its original state i.e a flat panel. Great stuff.

[Bikemad]

The foamex has a memory so when reheated it goes back to its original state i.e a flat panel.

I suggest you make sure that you don't leave it out in the sun or your battery pack will end up shrink wrapped.

You need to be vary careful that the materials you select are suitable for the expected temperatures otherwise this can happen:





Especially with our incredibly hot British climate!

Alan
 

[Andrew]

Haaaah,  you have a good point,   The temperature used to soften the foamex is around 200 degrees C.  I first tried using a heat gun to see if I could make it soften and it took quite a while just to get a corner to soften.   I used an industrial oven to do the job as a normal home oven was not big enough for the sheets I was using.

I may try and use hand tightened screw on knobs (male to female)to keep the two halves closed with a hinge on the lower edge which you can see masking taped in the photo.

http://www.ebay.co.uk/itm/291051325822?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

http://www.ebay.co.uk/itm/191037026008?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

[Marsbar]

Dirty Ginge, still have some cells? PM me...

Type?
unused?
how many?
price?
quality?

live in norway postage is cheap and fast from you, no tax on gift...

had to lower my controller to 16A to save battery meanwhile

[DirtyGinge]

hi bud

apologies, Norway is just way too far for the weight.......they do add up kilos really quick

I was thinking you were in UK for free collection

[Marsbar]

Nah! We are not sending SLA trough the mail here... for me postage from UK is dirt cheap, same price as internal in Norway...

You know Norway is expensive, 99NOK (£10 for a 0,6litre beer!)

Still, let me know what you have