One of my favorate parts of building EV’s is installing the batteries, its like giving the “All Spark” to the first Transformer robot.
The first step is rather joyful, using a saw-zaw I removed the entire stock engine cradle/sub frame. This consisted of 2 bent square stock aluminum pieces that held the engine and transmission under the bike.
Since this motorcycle is being made for maximum performance, and needs to have every possible ounce of weight eliminated I decided to use Aluminum “L” channel to produce my battery rack from. The aluminum battery rack was not inexpensive by any means, although the weight savings will be astonishing.
I started by measuring that 12 of the cells (3 packs of 4 individual cells) would fit nicely on the top and 12 more would sit right below where the existing drive train was. After carefully measuring all of the areas around the batteries I started constructing the 2 “battery baskets” which is basically “L” channel folded and welded around to hold the batteries in place.
After both “battery baskets” were constructed I measured and started making the corner towers. These will hold one basket on top of the other and also provide means of mounting the entire assembly to the motorcycle frame.
Whenever constructing a battery rack for an EV its important to remember the obvious, how are the batteries going to be installed and removed. Well in my case the center battery tilts upward and pulls out, then the other two slide to the center and tilt out as well.
Once the entire battery rack is constructed it’s time to measure and install brackets to hold the entire fixture on the motorcycle frame. These connections need to be made very securely for many reasons, the 120lb battery pack is big, and needs to withstand the harsh conditions of racing. The batteries need to be able to withstand an accident if the bike were ever tipped over. And lastly this will be the new jack pad for the motorcycle, so it must support the entire weight of the bike.
Quality aluminum welds are important when working with such a soft and lightweight material.
Before you know it, the batteries are safely and securely installed.
Its also important to note that I left about 2.5″ of space between the battery terminals and up. This was done because in order to install or remove any cell pack (4 individual cells) I will need to disconnect two of the terminals. therefore this space allows for ample hand and wrench space.
Also note in the picture above that the screws in the “L” channel are actually the hold down screws for the packs. I removed the bottom 2 from each pack, this allowed me to drill holes where these screws go and re-install longer screws through the aluminum. This keeps the batteries from moving around and also prevents them from falling out if the bike becomes inverted.
The jack is still able of holding the entire bike weight under the battery rack. The battery being the main weight of the motorcycle I placed it dead center and directly where the mass of weight was before to help handling and braking characteristics, especially important during racing.
This bike is finally starting to look good again!