A123 pouch cell padding question

ichaelm

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Aug 1, 2013
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I just have a question to ask about battery protection, hopefully it's not too unique and I can get responses from the people on this forum who seem to know way more about this than I ever will. Cheers!

I'm working on a motorcycle conversion project. I don't really want to get into all the gritty details because I'm crunched for time right now. Basically I have two piles of a123 pouch cells. They've all been connected pretty securely with bolts and washers plus some spot welding just as overkill, and I've bench tested them with the controller and motor and throttle, all connected together with the proper 1/0 gauge wire and soldered ring terminals, and they work great. All the terminals are joined by plastic shims and duct tape, so they don't rattle around on their own. Essentially I have two big columns running up the tabbed side, that go like this: tape, plastic, bolt, washer, tabs, washer, nut, plastic, tape, plastic, tape, plastic, bolt, washer, tabs, etc. There is no air gap in the columns. I also have a big sheet of HDPE to make two battery cases out of. The thing is, I really ought to put some foam padding in there, since motorcycles experience a lot of vibration, especially around my town. I don't want to use inch-thick insulation from home depot though, because it has way too much give, and it would be so thick the batteries wouldn't fit where I want them anymore. There's also some foam from a craft store around here that's about 1/8 inch thick, and that's pretty firm and uniform, but it seems like i'd be skimping out on what I really need. So I'm asking you guys who seem like you know what you're doing, unlike me, what should I be using to pad my batteries? Also, the motorcycle I'm converting has pretty good suspension, so I don't need this to be like impact-proof, but I also don't want the tab columns to vibrate until they fracture at the seams.
 
Just picked up a 6mm yoga mat, it seems perfect! Thanks for the advice. And as for compression, I don't want to get too fancy, but I will definitely make the final panel of the case the one that holds the z-axis in, so I can tighten the bolts down as much as I want without misaligning other holes.
 
I like to make relatively hard shell boxes for batteries out of discarded coroplast political and for sale signs.

The idea is, you make this very tight box for the pouch cells. Very tight fit, so there can be no rubbing of the cell itself on anything. Then yoga mats, camping sleep pads, and soft foam flooring materials can pad the space between the cells themselves and the box the pack fits into. All the tiny movements that chafe holes in pouches are then taken by the relatively tough coroplast material.

Others prefer harder materials for the tight fitting box. I have also used plastic sheet from storage box lids, aluminum cookie sheet, and old aluminum street signs to make the tight box. It just needs to be a durable material, pouches need protection from punctures and chafing. The most durable materials, such as 1/8 thick aluminum sheet, can be made so the box bolts securely. In that case, padding would not be needed, except perhaps some yoga mat in the bottom of the box.
 
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