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.
Remove these adsRemove these ads by Signing Up

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.
1-40 of 567Next »
abhinavp547 months ago

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

Stryker (author)  abhinavp547 months ago

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

sraju38 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

sirscotty747 years ago
Glad I came across this site. There really is hope. How much does the motor weigh?
Stryker (author)  sirscotty747 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.
1-40 of 567Next »