Battery Rack

Rack ’em up!
The batteries need to be securely mounted to the frame of the cycle.
This is typically done with a box shape or angle iron.

You do also want to keep in mind that the batteries are the heaviest part of the motorcycle. Ideally, they should be kept as close to the center of the cycle for front/back balance, and as LOW as possible for best center of gravity. Fortunately, that describes the big hole left by the removal of the engine and transmission.

The trick is to design a rack that fits in that space and holds the batteries.

A simple start.
In the earliest, experimental version of the motorcycle, I played around with something as basic as a “tray” put across the bottom two frame members. Small batteries could just sit right on top of that in a single layer. The larger batteries could only fit two there, so the others would have to be mounted in some other way. I experimented with “unistrut” – a slotted C-channel material available at building supply stores. It worked well in holding the batteries, but I didn’t like the looks. The batteries stuck out the sides a bit in a way I didn’t like.

Cut, Grind, Weld, Paint.
While the early version of the cycle was functional, I really wanted to get it cleaned up and looking nice. I had been practicing welding, and it was time to build a welded rack to hold the batteries.

The rack consisted of 1″ steel angle, cut to make frames that fit around the batteries, and tabs that would reach from the battery frame to an existing engine mounting point on the frame of the motorcycle. It would be made of several “layers”, because of the arrangement of the batteries – two on the bottom, and two mounted above them.

Essentially, there were four pieces:

1. Bottom piece. Connects to the bottom of the frame of the motorcycle. The two bottom batteries sit on top of it.
2. Lower-middle piece. This sandwiches down to hold the bottom batteries in place and connects to the front of the cycle frame.
3. Upper-middle piece. Holds up the top two batteries and connects to the front of the cycle frame. Sits directly above the Lower-Middle piece.
4. Top-Straps. These are just two pieces of steel that go over the top of the top two batteries to hold them down. Threaded rod goes through the ends to tie them down to the other parts of the battery rack. This is very similar to a typical tie-down for a car battery. (The top straps are insulated and don’t go near the top posts of the top batteries.)

Besides just being a square ring under the bottom two batteries, the bottom piece also had to directly connect to the bottom of the frame. To do that, I ran two pieces of angle iron the length of the cycle’s engine bay, so that it bolted right to the frame, again, through existing mounting points. It might be a little overkill, but gave me plenty of new attachment points for threaded rod to hold down the batteries, and another connection point for the motor mounting plate.

To figure the size of each rack piece, I simply put the batteries together the way they would fit, and measured them. I added just a little more to the measurement to give me some wiggle-room, and account for some thin weatherstripping to go between the batteries and rack when finished.

The tabs to mount the battery rack components to the frame were just flat steel – 1″ wide. I put the batteries and rack parts into the frame and test fit the spacing between the rack and the frame and clamped them in place. Then I removed everything and welded the tabs.

On the back of the rack parts, I welded some short bits of steel pipe, just a little larger diameter than the threaded rod I was using. These are “holes” that the threaded rod goes through to align all the parts and sandwich them together.

All rack parts were were painted with Rustoleum gloss black paint and the assembled into the cycle.

The finished rack looks nice and holds the batteries securely. The battery arrangement keeps them inside the body of the cycle. I was originally hoping to be able to just exactly clear the gas tank. In the end, the pieces of angle iron added up to too much total thickness. I notched the edge of the gas tank to make it clear the top batteries. The gas tank is hollow and covers the top posts of the batteries.

Take a look at these videos for more of what went into the battery rack design.

Next: CHARGING  —>