How to Build a 72Volt Electric Motorcycle

I only work 3 miles from home but with gas prices getting out of control, I thought it would be great to have an electric vehicle. I've always wanted a motorcycle and decided that making an electric motorcycle would be a good EV project, keeping costs down, and be fun to ride.

This project took about 3 months of research and development (not counting waiting for parts to come in or help from a friend with the welding). All in all, it cost about $3000 to buy and build. This may take a long time to pay off in gas savings, but if you add the fun of building and all of the environmental benefits, it was well worth the effort. With a top speed of over 70 mph and 10 miles per charge, this vehicle is perfect for me. The following instructable will not give you exact step by step instructions, but if you have some mechanical skills and welding ability you should be okay. A little knowledge of motorcycle maintenance wouldn't hurt, too. However, I just read the user's manual and learned as I went.

Every motorbike is different but the basic components can be the same. Below is a list of the parts I used and where I got them, but you will have to do some research to figure out what fits your bike and requirements. Check out the photos at the bottom to see what I bought and the EVAlbum for other electric vehicle projects.

Frame: I looked at many different bike styles and decided on a 1984 Honda Interceptor for a few reasons:
1) I like the style of bike, not a total crotch rocket but not a hog either, with room for batteries inside the frame.
2) The seller on Ebay was close to my house. And the bike didn't run, so it only cost $600. If you have an old bike or someone will donate one then that's great--but for the rest of us, try the local paper, junk yards, Craig's List or ebay motors.

Motor: After reading other EV bike specs (and knowing that I wanted to go faster than a moped), I chose a 72V Advanced DC motor, because it's weight and dimensions where good for my frame. I ordered it online fromthunderstruck-ev.com.

Batteries: I went with 6 Yellow Top Optima batteries from remybattery.com because they are sealed and have received great reviews. After making cardboard mock ups of the D23 model I realized that there was no way six full sized batteries would fit and still look good. I ended up getting the D51 model. Half the size and weight but also half the storage.

Controller: You have to match your controller to your voltage but the amperage is up to your budget. More amps = more power and more cost. It seems that there are only two real choices: Alltrax or Curtis. You'll have to decide for yourself, but I went with the 72V 450Amp Alltrax from cloudelectric. Don't waste your time trying to build a potimeter on an old throttle--just buy a pre-made one and be done with it. I got the Magura 0-5K Twist grip throttle from cloudelectric.com

Charger: You have to match your charger with your voltage but the speed of charge in Amps is also up to your budget. I went with a Zivan NG1 from EVAMERICA I have recently switched to six individual 3amp Soneil chargers to help balance the batteries.

DC/DC Converter: It's safest to run with a DC/DC converter and an extra 12V battery backup but motorcycles have limited space so I am only using the converter. I purchased a Sevcon 72V Input 13.5V output from evparts and it has working perfectly.

Fuses: You'll want to get a fuse that matches your setup. I bought model ANN 400 w/ holder from EVAMERICA.

Contactor: This is a device that you hook up to your existing key ignition on 12Volts and it will close the loop so you get the full power to your controller. I bought an Albright SW-200 from EVAMERICA

Battery cable and connectors- I bought about 10 feet of 2 GA wire from WAL-MART and cut it to length. Using Lugs from cloudelectric I soldered and used heat shrink tubing on each end. I highly recommend battery terminal covers for safety.

Instruments I chose an E-meter(Link 10) w/ Prescaler add on for 72V use instead of a bunch of different meters. As an added feature I wired up the ignition switch to the neutral indicator to show me when the bike was on.

Other parts
Wire - 12GA different colors and heat shrink tubing (large and small sizes)
Electrical tape
Wire connectors
Wire wrap

Tools
Basic shop tools are required such as a socket set, screw drivers,wire stripper, etc. Additionally a volt meter, metal grinder and crimper are used in this project.

Start by removing all of those nasty internal combustion engine parts. Remove the gas tank and using your grinder or other cutting tool to cut out the bottom. This makes room for extra batteries or components. (Make sure all gas is out before cutting) Reference your owners manual so that you don't cut any necessary wires, and try to sell some of the parts to help pay for this project.

Next, make cardboard mock ups of all of your batteries and electronic components to see how and where things are going to fit. Take a look at my pictures to see how I fit everything, believe me that taking the time to make accurate cardboard mock ups is well worth the effort.

Now for the hard part. You need a secure battery box and motor mount. I had a friend weld it up for me and he did a fantastic job. From the photos you can see that he first strung up the motor to allow for minor adjustment to be made before cutting the motor mount plate. After that was cut he made a nice chain and sprocket enclosure with a door and welded them onto the frame.

Next he fabricated the battery rack and gave each battery a swing arm closure to give a tight fit yet still allow me to get them out easily. Half inch foam padding spacers are between each battery to help cushion the stack--but believe me, they aren't going anywhere. The last thing
he did was weld in metal plates for mounting my electrical components.

After you get your motor mount and battery compartment all welded up, take some time to clean up the frame of your bike. I removed any rust spots and chipped paint that I could find. Then I used some metallic gray and black spray paint. This makes a world of difference and costs very little.

I made a fake gas cap and ran the power cord from the charger up the frame and out the top.

Now that you have all of the welding done and your frame looks great, let's install the electrical components and start wiring it up.

If I tried to explain where to connect every single wire I would get writers cramp. View the wiring diagram that I put together and let me know if you have any questions. This diagram should be pretty accurate to how I built mine, but obviously you are responsible for your project.

Double check all of your connections and tighten every bolt.

I wanted my bike to look as good as it rides, so I had all of the panels painted and custom graphics made up by worldsendimages.

Using a serial cable and laptop, tweak the speed controller program for your riding preferences.

Lastly, I got the bike inspected and insured. (Be prepared for the dealership mechanics to swarm and hit you with a bunch of questions and jokes about failing the emissions test).

I know these weren't step by step building instructions, but that's because of the complexity of this project and variables in component use. My intention was to give you the motivation to build your own by seeing how I did it and make it easier by supplying the parts list and a wiring diagram.

For more photo's and a build commentary visit my website at http://ben.cbccinc.com.