Wednesday, March 11, 2009

Front Battery Boxes

It occurred to me that I'd better start solving any problems with fitting batteries in the front end. I spent some time building some cardboard trays that would hold the cardboard batteries I built. All the cardboard mock ups that I made are carefully built to match the actual size of the batteries I intend to use. I'm planning on using 11 Crown 31D36 12V batteries, for a total of 132 VDC and approximately 18.5 KWh. Originally I wanted to use 14, but there simply wasn't anyway to accomplish that.

As you can see, I'll be able to fit 7 batteries up front quite easily. Under the front battery box is plenty of room for the accessories I'm going to use, A/C system and power steering pump and vacuum pump for the brakes. The three batteries back by the firewall will end up being about the same height as the two directly in front, I just couldn't find anything to hold them up there. Eventually, there will be some pretty substantial bracing to hold them up.

I haven't decided what to make the actual battery boxes, or trays out of. Fiberglass is out, not enough room. As I see it, I could use steel or carbon fiber. They measure up like this. Steel is cheap, but heavy. Carbon fiber is light, but decidedly not cheap. I have a few weeks to decide.


Gam0ra said...

Is there some reason you can't use aluminum? Cheap, light weight, easy to work with.

I love the cardboard mockups...very good idea.

Tim Catellier said...

Yeah, you're right, aluminum may be a good compromise. I don't know how much weight it would save over steel. You have to use a heavier gauge than you do with steel so that it can support the weight. But I think it would be lighter over all. I ruled it out at some point, but now I can't remember why. Might have been cost, which makes my considering carbon fiber really dumb :)