Instructables
Picture of Build Your Own ELECTRIC MOTORCYCLE
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OVERVIEW

The finished project is a 1981 Kawasaki KZ440, converted to electric. It is powered by four Optima Yellow Top sealed (AGM) lead-acid batteries, that drive a Briggs & Stratton Etek electric motor. The speed of the motor is controlled by an Alltrax brand "AXE" programmable controller that can run at up to 48 volts and 300 amps. Contrary to popular belief, and electric motorcycle is NOT silent, but is CONSIDERABLY quieter than a typical gas cycle.

The cycle is GEARED to 45 mph, has fairly good acceleration, no clutch or transmission. There's no oil to change, to mufflers to rust off, no air filter, no carbs to tweak, and no gasoline. I designed it for primarily city riding. The top speed and acceleration could be easily changed by swapping out a $20 stock sprocket.

The cycle recharges from the wall, through a renewable energy program, and if there is a blackout, I can actually run my house off my electric motorcycle! In the future, I hope to expand my system to include charging the cycle with photovoltaic solar panels. Real-world range per charge is 23-32 miles, and charging takes less than 10 hours for a full charge. ( A different charger could charge them even faster - see details on the Batteries PDF)

In this Instructable, I'll walk you through the work required with the motor, batteries, controller, and mounting all components, including showing you some low-tech paper and cardboard "CAD" tricks.

Your Project
But what do you want? You might not even know yet. I always encourage people to take a look at the EV Album. It's an on-line listing of mostly home-converted electric vehicles. Each listing shows the make and model of the vehicle, the cost to convert, the speed and range, and other specifics of each project. You can also search by type of vehicle or brand name.
For example, if you go to http://www.evalbum.com/type/MTCY , you'll see a wide variety of electric motorcycles. Different brand names, lithium and lead-acid battery types, and a wide range of costs of conversion. Likewise, if you want to see Scooters, Mopeds, and Minibikes, you can visit http://www.evalbum.com/type/SCMM

Give some thought to what cycle you would like to convert. Do you like sport bikes? Great! They have a lightweight and strong aluminum frame! Do you like standard? Great! There's lots of those out there and you can show off the motor and batteries. Hang out at biker events with your unique ride!

If you aren't sure what to expect in terms of range per charge and top speed, don't worry, online calculators can help you out.
EV RANGE/SPEED CALCULATOR
P
ower Use at Speed Calculator
and of course, a
GEAR RATIO CALCULATOR

For more on my electric motorcycle, electric car, and other projects, swing by my blog at http://300mpg.org/

If you are interested in building your own electric motorcycle, but want even more information, more details, and hands-on style instruction, check out the INSTRUCTIONAL VIDEO DVD that I created to teach how ANYONE can Build Your Own Electric Motorcycle!


 
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oyvisan3 months ago
My key switch can switch two circuits, one like a normal switch and one for an ignition (spring loaded). Which one am I supposed to use?
bennelson (author)  oyvisan3 months ago
You just use a regular on switch.
oyvisan5 months ago

What happens when you release the throttle? Does the motor just keep going in "neutral", or does it start breaking? Also, do you know what the "plug brake" switch in the controller settings does? (I'm using the AllTrax ControlPRO software).

bennelson (author)  oyvisan5 months ago
The vehicle just keeps moving forward in "neutral". There is no regenerative braking setup on my project. Kelly controllers support regen, but I've never heard anything good at all about the quality of that brand of controller.

Plug braking is a way to use the motor as a brake by shorting the system. It slows you down, but does NOT regenerate power. It's typically only used on off-road vehicles, such as forklifts and golf-carts.
oyvisan bennelson5 months ago

Alright, thanks! How do know how you activate the plug braking, and how fast it's breaking? We're building a monowheel, so we need a slow and steady breaking and it would be great if we could do that with just the motor.

bennelson (author)  oyvisan5 months ago

I haven't used plug braking, but I believe you use a reversing contactor, and then the throttle controls the braking. Consult the motor controller user manual for details. Alltrax has nice online versions of their motor controllers that you can download. http://www.alltraxinc.com/Doc_Depot.html

Aditya M5 months ago

It's really nice

i have a old panhead frame that i accuired from somewhere that i am thinking about making a ebike from it but i need to 55 miles round trip
Please don't cut up a pan head frame! That is history. I bet you could find a good Japanees frame to trade and still walk with a bunch of money for mechanicals or batteries.
bennelson (author)  thelurchmanfl2 years ago
Lithium batteries are where it's at if you need a range greater than 50 miles. Lead-acid works fairly well for anything less than that.
wouldnt that require a special charger
how would i make the battery pack out of a whole mess of aa type like the tesla roadster
and would this charger work
http://www.all-battery.com/TenergyBatteryCharger01224-1.aspx
bennelson (author)  thelurchmanfl2 years ago
Making a battery pack from cells that small sounds like a lot of work!

Remember, you need to have enough cells in series to get to the voltage you want, and enough cells in parallel to get the capacity that you want.

I haven't heard of anyone building projects with AA cells. There are a few projects that people have built from cells pulled out of DeWalt lithium cordless drill packs. Those are more like C or D cells.

That charger is the right chemistry and voltage, but it may too low amperage. My battery pack is 55AH at 48V. If the pack is run half-way down (23AH) and you recharge it at a rate of only 2 amps, that's going to take 12 hours to recharge, and a fully discharged pack might take a full 24 hours!
bennelson (author)  thelurchmanfl2 years ago
Lithium batteries with either use a different charger, or at least a high quality one that is programmed for lithium. Lithium batteries also typically need a battery-management-system.
bilalz4001 year ago
Can you use the existing transmission system of the bike??
bennelson (author)  bilalz4001 year ago
On most motorcycles, the engine and transmission are really a single, integrated unit. It's very difficult to remove the engine, but keep the transmission. You CAN build an electric motorcycle with a transmission, but the tranny takes up space that might better be used by having more batteries.

What a transmission in general really does is convert engine speed into torque. Electric motors tend to have HIGH torque at LOW speeds, so you don't neccessarily need a transmission.

For a commercially-built EV cycle WITH a transmission, take a look at the Brammo Empulse.
But couldn't you gear that high torque down to get better top speed/further range?
bennelson (author)  bertzie1 year ago
For higher top speed, you would use high gearing, which would pull greater amps. Pulling higher amps creates more heat, shortens battery life, and reduces how far you can go per charge.

In general, to increase top speed, you are best off increasing your system voltage.
migglez8131 year ago
how fast can it go?
bennelson (author)  migglez8131 year ago
I live right outside a city, so I geared the cycle low, to a 45mph top speed (the speed limit right outside my house).

Changing the cheap front sprocket out for one with a few more teeth would give the cycle a 65 mph top speed with no other changes.
shinigaimi1 year ago
Hey all, Great instructable Ben!

I am wondering if anybody knows a reputable place and possibly a wholesaler that sells lithium batteries? or if other batteries are better than AGM lead acid batteries? that wont cost an arm and a leg :)
bennelson (author)  shinigaimi1 year ago
I haven't ever ordered lithium batteries, but the prices are continuing to fall. Another advantage of an electric motorcycle is that the battery pack is smaller than an electric car. So, if you DO want to pop for lithium batteries, it's always going to be more affordable than a car.

The Electric Auto Association is also a good place to start for general info, including some vendor links.
http://www.electricauto.org/?page=EVinfo
itscasper1 year ago
The Optima Yellow battery specifications state good for 300+ discharge/recharge cycles. Does this mean you potentially have to replace your four batteries once a year for a daily driver? Even every two years seems a steep price. Do the batteries degrade slowly over time? I'm very inspired by your instructable!
bennelson (author)  itscasper1 year ago
I've had my Optima Yellowtops for 5 years now. Still working great.

If you don't "dig too deep" in discharging, batteries last much longer. My average trip is 10 miles, so I'm typically discharging the batteries only about a third of the way.

I do sort of baby my batteries, but they WERE the most expensive part of the entire project. By taking good care of them, and always recharging them right away, they have been great!

As far as lead-acid batteries go, I don't think I could be happier.
This could be the best write-up I have ever read. Thank you so much Ben for this wealth of information! But, I do have a few questions.

1) Does anyone have a simple schematic for the electrical? I've looked at Alltrax's schematic, but it includes all sorts of diodes and extra fuses that I don't think are really necessary.

2) What is the coil voltage for the contactor in this project?

3) What is the voltage rating for the keyed switch?

4) Could you just use a heavy duty red switch in place of the entire contactor?

Thanks!
bennelson (author)  charlesfries2 years ago
Curtis also has nice wiring diagrams in their controller manuals. Really, I can't draw one any nicer than they already have! See page 9 of this Curtis Manual for a good diagram.

The coil voltage on this cycle is 12V.

They keyed switch is rated for 48V.

Yes, you could use a very heavy-duty switch in place of the main contactor. The advantage of a contactor is that it REMOTELY controlled, so a very small and conveniently-located switch can turn it on and off. It's also easy to rig one or more safety switches in series to the main contactor. For example, so that you can set it so that the drive system can't power up if the kickstand is down, etc.
What I really don't understand is the wiring diagram for the Alltrax AXE4834.

http://www.alltraxinc.com/files/Doc100-081-A_DWG-AXE-PermMag-no-Rev-wire-dia.pdf

Some of the parts in the diagram I am confused about:

Diode IN4004

6AMP Diode Reverse Protection

Fuse 5A Max

Are these parts really necessary? What do they do? Thanks!
bennelson (author)  charlesfries2 years ago
Yeah, I guess those parts are a little confusing....

You SHOULD have a DIODE IN4004. It just goes across the main contactor. Since you are using a magnetic field to hold the contactor shut, when you turn it OFF, that magnetic field collapses and creates voltage. I theory, it can get pretty high and create a brief spike of voltage that can be bad for components. The diode stops that from happening. You can get that part at radio-shack, it's no big deal, but you should have one.

The 6amp Diode reverse protection - Frankly, I'm not sure why that's there.... I don't see anything that should cause a reverse of polarity that should be protected against.

The "Fuse 5A Max" you should have - it protects the logic portion of the motor controller. Pretty much anything with power running through it should be protected by a fuse, including your "ON" power through the key switch.

One more note on this particular controller. On the diagram, you can see that Pin #1 is right next to buss bar B-...... Note that Pin#1 connects through the keyswitch to the plus side of the battery pack. That means you practically have both ends of of your battery pack coming together to only half an inch apart. Always make sure that ALL POWER IS DISCONNECTED when working on your motor controller. Keep in mind that some power can still be stored in the capacitors inside the controller. A short circuit from accidentally touching the pin#1 wire to the B- bar (like when giving it a tug to pull it off) is enough to vaporize a 1/4" spade connector. Please use insulated spade connectors.....

That 5amp fuse can also be pulled when you work on the controller as well.
What happens when you back up, say like backinging up to a curb to park? If you use a small forward throttle response to act as a brake as you would on a ICE bike, you might reverse polarity or generate a small amount of reverse polarity power. Just like yanking a piece of paper out of a printer and frying it.

Just a thought......... Cool Scoot BTW.

Dan
bennelson (author)  dlemke1 year ago
I don't usually even have the power on when I am backing out of my garage or backing into a parking space.

Built in to the motor controller are diodes that prevent the improper back-flow of power. You'd have to be backing up pretty fast to be able to generate any amount of power at all, but no worries, it's not a problem.
crackHacker2 years ago
i love this and i liked the car conversion you did. my question is: why not use the motor to charge the batteries as it moves? or maybe a generator to capture the energy from the wheel(s) as they turn to charge the battery? i know that the bearings are not up to snuff yet to replace the center of the wheels but maybe mount something above the front wheel physically connected to the wheel by chain or belt drive that does nothing but charge the battery as your moving down the road?

i dont know was just a thought due to the fact charging takes freaking forever and i am sure if i built this i wouldn't be allowed to charge it at work: government employee, making it impossible to get home likely.
bennelson (author)  crackHacker2 years ago
You have to keep in mind that energy has to come in from an EXTERNAL source. On a gas vehicle, it's when you put the gasoline in the fuel tank. In an electric vehicle, it's when you charge it from the wall.

The stored energy in the batteries powers the motor, which pushes you down the road. If you have any sort of mechanical dynamo or generator running from the wheels or motor, this puts additional load on the batteries, thus wearing them down faster. Generating electricity comes at the expense of mechanical motion, thus either wasting battery power and/or slowing you down.

The only time this makes sense is when you WANT to slow down. That's the "regenerative braking" that you hear about on hybrids and electric cars. You regenerate a small amount of energy by converting mechanical energy (slowing you down) into electrical energy (to put a little power back into the batteries.)

To use the batteries to power the motor to turn the wheels to run a generator to charge the batteries has no external energy source, so all that can happen is losing energy (generally as heat and friction) by converting it to another form.

One fun project might be a generator side-car. The side-car could carry a generator and fuel tank, and would connect to the motorcycle's batteries. If it were rated for the average energy use of the motorcycle, it would just run continuously, more or less passing the energy through the battery pack to the motor. (Think of a Chevy Volt version of a motorcycle!)
I am beginning to think that in order to sign up for an account here instead of doing a Captcha you should have to prove you've read and understood the laws of thermodynamics...
are there batteries with higher than 55 amps that i could use
bennelson (author)  thelurchmanfl2 years ago
Sure, batteries are available in a number of capacities. The next size up is right around 100AH.

For my project, they wouldn't have fit inside the unmodified motorcycle frame, but would be great for a "chopper" or custom frame.
What was the total amount to do this?
bennelson (author)  simpleplan5712 years ago
$2000
The budget is laid out in Step 14.
I just started on electric toy. I'm converting a Wheel Man G-Wheel
http://m.youtube.com/watch?v=2CptvxAdOdA
to electric power charged by motion. Never running out of power sound great. Check this out and think of the custom fit application on all of your toys. http://www.synchrony.com/products/magnetic-bearings.aspx?_kk=fusion%20bearing&_kt=0315a12d-4121-4ddc-9f5e-988d79a13269&gclid=CJCB59yo6bACFUFV4AodnVKUhg

Thanks to the Wheelman Club of Moscow for making such a great video that shows the advantage of superior transportation.
RichieRichSr
dattajack2 years ago
First off, love the detail provided on this project. I plan to use it all summer until both wheels are rolling down the street. I'm all about converting the guts of the vehicle and keeping the soul. Not every bike you want to make immortal will have a nice open frame. If this is the case, you can transfer the existing frame into SolidWorks, or some other 3D drafting program, and from there you can design a new frame to fit your electronics, motor, and batteries. SolidWorks, and a few other programs, have fatigue testing ability. In this case vibration and static loading would be the main causes of failure to your new frame designs. Iterate the design as needed. Don't let a good soul die.
This was supposed to be posted on the "which frame to use" slide. In hopes one or two readers would not decide to abandon their donor bike just because it had a small frame. :) sorry for the confusion.
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