# Battery Box Design



## MN Driver (Sep 29, 2009)

Quick question, I thought about this the other day and this post prompts me to ask. Would a pond liner grade PVC(super cheap) be suitable for an electrical application in the voltage ranges that we have for EV's? I figure if this isn't good enough there is always the thicker EPDM stuff but that's a little more spendy and about 1/8" thick, which might be good to prevent a tear that might expose a conductive box like aluminum.


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## UBCECC (Sep 5, 2009)

how are you guys securing the battery down? There is virtually no place on top of the battery to put a bar across without blocking the vent.


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## TX_Dj (Jul 25, 2008)

The "brick" style LiFePO4 *REQUIRE* you to strap them together TIGHTLY between two plates, like so:









If you don't, they WILL "bloat" which destroys them. The clamping force is required to give the necessary rigidity to the long sides to withstand the pressures that build up inside them (the vent blow-off pressure is necessarily very high).

To secure them in the vehicle, you just simply have to come up with a way to secure the end plates in the box. The straps that go around each "sub pack" fit into grooves around the batteries and in the end plates. These plate/strap kits should come with any quantity order of batts from any reputable vendor.

To the OP: yes, carbon is VERY conductive. This is one reason why carbon-zinc was a very popular battery chemistry for decades. If you're curing the carbon with heat and a coating of resin, this should probably be sufficient to protect against conductivity, so long as the resin is thick enough and nothing chafes it to the point of exposing the carbon. Then again, your battery terminals, bus bars and cables, should not be in a position to make metal-carbon contact, just as would be the case with any metallic battery box.


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## CroDriver (Jan 8, 2009)

Carbon fiber is ALWAYS conductive. Even if it's painted, it's not worth the risk. You can use kevlar or glass fiber.

Here is my ThunderSky batt box design:


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## UBCECC (Sep 5, 2009)

CroDriver said:


> Carbon fiber is ALWAYS conductive. Even if it's painted, it's not worth the risk. You can use kevlar or glass fiber.
> 
> Here is my ThunderSky batt box design:


I like how you made the straps on top. What kind of material is it made of?


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