Picture of How to build a 72Volt electric motorcycle

No gas, no oil and almost silent. 72 Volts, 70mph of pure fun. This is how I built an electric motorcycle.
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Step 1: Why and how

Picture of Why and how
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.

Step 2: Components and tools

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

Batteries: I went with 6 Yellow Top Optima batteries from 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

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

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.

Step 3: The build

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.

Step 4: Wiring

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.

Step 5: Last few things

Picture of Last few things
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

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abhinavp546 months ago

What power batteries and motor do I need to get in order to get at least 50 miles per charge

Stryker (author)  abhinavp546 months ago

I'm not sure, but I would say a lot......

sraju37 months ago

sir,i want to build a electric motor cycle which should have top speed of 50-60mph and it should have a mileage of 70-80 miles per charge would anyone can suggest me required motor,batteries and controller set ups

sirscotty746 years ago
Glad I came across this site. There really is hope. How much does the motor weigh?
Stryker (author)  sirscotty746 years ago
72V Advanced DC AC4-4002 10”x 6.7” 47 Lbs from
tcase Stryker6 years ago
Just out of curiosity, have you ever thought about a good generator, like off of a car or something?
Car alternators really aren't all that good. There are better options, though with something like this, one might like to go custom. Maybe use permanent magnets instead of coils, that also would aid in battery life. That's kinda intentional though, like the 18% fuel efficiency they have so you have to buy more gas and your engine wears out sooner.
Thanks, thats very interesting, My father in law brought up a diesel engine alternator, or simply deal with he's been a mechanic for years, sometimes an annoying one that likes throwing wrenches at customers who try to tell him how to do his job, but a good mechanic. He likes the idea of saving money for gasoline by other alternatives, solar power or if you have a creek on your property build a wheel like the old days, I forget what its called, but putting a generator on that to make electricity. anywhere you save money can help. then just dish out the money for gasoline at the pump. I kind of fancied the air compression engine actually, going to try that someday... still takes money though. take care and great Instructable.
I read something about a hydrolic compression engine once. Done by a University class (maybe University of AZ, not sure). It used a combustion engine, but instead of driving the car with it, they used it to build up hydro pressure, then use the pressure to drive the car. Could get up to speed reasonably, and stored breaking energy to allow smooth take off from stops. That would probably fit the same principle as your air compression idea, at least for design purposes. Got like 80 miles to the gallon. The wheel you spoke of is simply called a water wheel, though there might be another (more proper) term.
I think I saw an article in Machine Design magazine a while back about using hydraulic motors to drive wheels, one motor per wheel. it is possible to use a gas motor to drive hydraulic pumps to produce power, dump truck, garbage truck. bull dozer, ect. ect........
Thats cool, I think my biggest problem is having something that goes the distance for an electric... you get on a motorcycle today, and its like, you can refill anywhere, yea, you can plug your bike into plugs at grociery stores, but to me, according to one person, he plugs his car in at the light poles in parking lots.. like walmart. to me, thats still stealing, even though it is available... I want to find a way to build an electric motorcycle, ( Im a fan of the sportster models ) it still look good, and be constantly recharging while driving.. kind of like having an alternator from a big truck similiar to a dump truck or semi. Im not sure on how to put all that together considering I have nothing to use to start experimenting yet... I have to wait to buy a house before I can start tinkering, thanks for the last comment It sounds like it would come in handy... or at least experiment with.. My uncle works with a backhoe at work they have alot of parts just laying around I might be able to pick up for a few dollars for alot of their heavy machines... but I dont think I need to build a tank, even though it sounds like fun...thanks again..
lucek tcase1 year ago

You'd be talking about reactive breaking then. It'll help but I'm not shore if the extra weight will overcome the savings in energy. After all just because you slap an alternator on it doesn't mean it's making energy. It's taking energy from the battery to the motor to the bike to the breaks to the alternator and back to the battery with losses at every step.

Nyxius tcase5 years ago
Using your alternator to charge your batteries while you drive will only kill your batteries faster. alternators have maybe 50% eff. converting kinetic energy to electric. but the full load is being introduced to your electric motors. Thus you may be getting a couple watt charge out of it, but it will consume far more than that in the extra juice needed to power the motor.
swander Nyxius3 years ago
using an alternator while braking would regenerate otherwise wasted momentum. Make a switch into your brake lever that activates or "turns on" your alternator that would otherwise be free wheeling, making no power with minimal drag. When you turn it on, you can regulate the amount of "exciter" voltage and the amount of drag the alternator will be putting on the freewheeling wheel. more braking. more drag, like a jake brake in a truck. Wont use it all the time only when it is safe like on a downgrade or slowing for a light.
J-Ri swander3 years ago
Why add an additional part? The motor can be used as a generator if regenerative braking is desired.
swander J-Ri3 years ago
Because you can regulate an alternator easier than a generator. also alternators have better low RPM efficiency. Regulate with input voltage or variable ground, your choice.
J-Ri swander3 years ago
I do agree that it is easier to regulate an alternator, but only slightly. An N-channel MOSFET connected to ground would use the same PWM as an alternator's field terminal. Many alternators use a 12v (or 24v) field signal, and some provide the current for the field coil as well, either of those cases would require a transistor anyway.

Could you provide me a link to some documentation that says an alternator has better low RPM efficiency? My research in wind turbines suggested that at best, alternators and generators have the same efficiency at low speeds, and most seemed to agree that generators are better at low RPM.

A transistor controlled ground is one more part, and a much cheaper, easier, smaller and lighter one to install than an alternator. I suspect it would also be difficult to find an alternator that can output this kind of voltage. Many have a fixed regulator that won't allow excess voltage in the event that the computer controlled one malfunctions and full-fields, and even one without that protection probably isn't built to output this voltage and may fail prematurely. Even on a car where the alternator is typically driven at approximately 3-5 times faster than the crankshaft, the voltage will drop to below the desired charge voltage with only a few amps drawn at idle 500-1100 RPM (1500 to 5500 RPM at the alternator). So that alternator designed to output 12 or 24 volts would have to be geared up considerably, further adding weight and frictional losses from the gears. An additional load on the motor would require more power from the motor to spin it up to speed. Try spinning one by hand, the rotational mass alone would take considerable power to get moving, especially with the gearing required to spin it fast enough to make this high a voltage.
swander J-Ri3 years ago
simply going by what the car industry did back in 1965 when some went to alternators instead of generators for better low speed charging ability. Now stepping these up to 72 volts is out of my pay grade. efficiency between 50-62% is typical of an automotive alternator, they are cheaper, lighter and are more durable with low current slip ring brushed instead of full voltage DC brush design. 1200-1800 RPM is generally idle speed in a automotive alternator, and they are in almost unlimited supply in varying amperage output from small 30A tractor units to 240A modern car units. Cheap is good.
J-Ri swander3 years ago
The primary reason they switched is that alternators are smaller and lighter for the same output, but we already have a dc generator (the motor) on this bike. The rated amperage is only short term (but likely acceptable for use as a regenerative brake), for sustained output, they have a maximum of half their rated value. And the higher amperage ones are huge, a 180A alternator from an F-350 is larger than the motor used on this bike and weighs 20 pounds (a guess).
Nyxius J-Ri3 years ago
If you are insistent on regenerative braking (using the motor), may I suggest using a brush-less motor coupled with some super caps. Batteries don't like the sudden spikes in voltage that regenerative braking gives. You need a way to smooth that out over time, or your going to kill your batteries. Regenerative braking is essentially a collapsing magnetic field with an inductive coupler (rate of field collapse is motor dependent). Without something to buffer your batteries, your electrodes in the battery will start to breakdown (beyond what is normal) and will probably cause a breakdown in your electrolytic material as well. This generally results in electrolytic gassification. This is why liquid capacitors burst and this is the reason they say to not overcharge batteries.
Also, regenerative charging using a brushless will most likely require a weird bridge rectifier (3 phase+) with a negative feedback loop.
Nyx is pretty accurate, you can't receive a net gain in power while using the same type of energy to drive the vehicle.

You would need an external source of energy input into the system while driving.

It would be possible with large scale technology similar to the proximity charging devices we have recently developed for small electronics. But the cost to create such tech on a large enough scale to charge while on roadways is not feasible at this time.
 I think you refer to Hydroelectric power :D
No, it was driven by hydrolic pressure, not electric motors. I'll ask my dad if he remembers the University that did it and post more info.

Sorry about the late reply, been away from the site for awhile.
 Lol i meant when you said this: 

"The wheel you spoke of is simply called a water wheel, though there might be another (more proper) term.

but yeah, the type of engine you spoke of originally has actually been produced, and soon is supposed to be commercially made, although it's actually a pneumatic engine that refills it's tanks when plugged in. :D sounds pretty sweet to me
Could you repost a link for the motor? I can't seem to find it.
Great job everything looks good. Is bike still 4 sale
Today is 11/01/2013.
Stryker (author)  jesus prado1 year ago
Yes it is. I upgraded to Lithium batteries but haven't ridden it in a while.
Diozark1 year ago
How Did You Connect The DC Motor Shaft to The Drive Sprocket ?
Stryker (author)  Diozark1 year ago
The sprocket has a set screw and the motor shaft has a flat spot to screw onto.
Hai how is your motorcycle working now. ?
Would you like to share some knowledge of yours experiences
Stryker (author) 1 year ago
I'm sorry I don't know.
jehuty98001 year ago
what king of current is the motor drawing, running at? im doing my research before i convert my old 82 honda nighthawk into an EMotorcycle. 72 volts seems like its the best option, i just need to know what the amperage is that the motor is drawing.
nehmo1 year ago
Lead-acid? The main thing I learned from my e-bike experience, which is ongoing, is shun lead-acid. They are inferior to the lithium chemistries in specific energy, cycle life, and C-rate.
kelevra882 years ago
How long could you expect to get from these batteries ,Mileage and/or lifespan?
scubaru3 years ago
What are some of the specs:

How many HP is the motor?

Top speed?

That motor is probably no more then 3 or 4 hp. Top speed is 70mph.
alenz12 years ago
The bike was beautiful and tidy and better: clean, quiet and it seems pretty fun. Congratulations!
Would anyone like to view/correct my schematic for a 24V system with an Alltrax controller?

i think your good but its kinda hard to read it might help if you color coordinate and spred it out a bit
plz give me motor RPM of this bike.
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