Battery Boxes

My electric truck has 24 US-2200 6v golf cart batteries for a nominal 144v system. I decided to store the batteries in insulated aluminum battery boxes. I tried to fit 4 batteries under the hood but I could only get three, so I have 21 batteries in the bed. That gives me 3 battery boxes, 3 batteries under the hood, 20 batteries in the big box in the bed and 1 battery in the small battery box in the bed. This photo is of the large battery box in the bed before the insulation has been installed.

This photo shows the large battery box with the insullation installed. I used 3/4" foil backed foam insullation sheets. The 2" x 1" wood strips are used to support the batteries other wise they would crush the foam (1" thick wood is actually 3/4" thick, the same as the foam insullation). The wood is expoxied to make it more acid resistant. The inside of the battery boxes and lids are also painted with special acid resistant paint that was designed for airplane battery boxes. There is a lot of talk in the electric car literature about acid being spit out during charging of flooded lead acid batteries but I have not seen it in my truck. My batteries are perfectly dry and clean. From what I understand US Battery is using new caps on their golf cart batteries and I think that is what is keeping the acid from spattering out. So it may not be necessary to take all the anti-acid precautions that I took with these battery boxes.

The small round cut-out is for the cables to the single battery. There is a similar cut-out on the near side that you can't see for the cable that carry the high voltage DC up to the front of the truck. The battery boxes are mounted by bolting them through to the frame of the truck.

You can see the small square cut-out in the front wall for the 12v exhaust fan to vent the hydrogen gas generated during charging.

Once the batteries are installed spacers of corragated plastic (called coroplast) are used to snug up the extra space to keep the batteries from shifting. I also plan on stringing soil heating wire through the coroplast to keep the batteries warm in the winter.

This photo shows the front battery box and the electronics mounting plate installed under the hood of the truck.

This photo shows the 3/4" epoxied piece of plywood that the front battery box is bolted to. The frame that supports the battery box is made from 1" tubular steel (painted with rustoleum). The frame supporting the electronics mounting plate is made up of 1" aluminum angle stock. You can also see the front of the electric motor in the photo and the notch in the plywood for the tailshaft of the motor.

This photo shows me painting the tailshaft black and white (just black first) to use with the optical tachometer sensor. You can get a better idea of the framework that made out of 1" tubular steel to suppor the battery box.

The battery boxes were designed by two of my coworkers Dave Sund and Brad Brunker and built by the metal shop at ETC where I work. The boxes and lids are made of 1/8" aluminum folded into shape. I fastened them together with aluminum rivits from McMaster-Carr.