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Twist Throttle

The old way on gasoline motorcycles was to have the twist throttle connect to a steel throttle cable to open and close the throttle valve on the gas engine.

Early electric motorcycles mimicked the mechanical system that the gasoline counterpart used, connecting the steel throttle cable to a clunky Curtis PB-6 pot box that many electric forklifts still use to communicate with the speed controller.

Modern electric motorcycles can now use an electronic twist throttle, the electronic throttle has a few electrical wires coming out that plug right in to the speed controller, when you are shopping for electronic throttles you’ll see a few types out there, the easiest throttle to work with is the 0-5K resistive twist throttle.
Some brands of speed controllers are starting to support a 0-5V Hall Effect throttle, so keep an eye out for new options.

New Options, for many years the Magura brand 0-5k ohm twist throttle was pretty much your only option and they have many happy customers, but now you have another choice thanks to a company called Domino that recently showed up with a 0-5k twist throttle for around $90 that looks to be even better built.

Speed Controllers

The box of solid state electronics that sits between the battery pack and the electric motor is the speed controller, communication with an electronic twist throttle tells the speed controller how much to vary the voltage going to the electric motor and thus controlling the speed of your motorcycle from a crawl, all the way up to full speed.

There are two main types of golf cart motor speed controllers, those for Series Wound motors and those for SepEx motors also known as Shunt Wound, and they are not interchangeable.
Less common in Golf Carts and NEV’s are 3 Phase, or brushless  AC motors and they are ideally matched with a motor controller/3 phase inverter.

How many Amps a speed controller is rated for can be deceptive.
You’ll see the peek rated or labeled amps of a controller and depending on the company it might be what it can put out for 10 seconds or others it’s up to 2 minutes, motors tend to have the same types of ratings, a  peek and continuous output.
Depending on your use, you’re going to want to look at the one  hour rating , that tends to be around 1/3 or less of the peek rating.
For example if you want a motorcycle that can cruse at 55mph and has a 48v battery pack, a 300amp speed controller with a 125amp 1 hour rating will be working at it’s limits most of the time, so on hills or hot days it might start cutting back where you will feel a loss of power.

A  non programmable speed controllers that tend to be burned in with a soft start designed for golf carts, while you can build a motorcycle with one of these controllers, it’s initial acceleration will be slow and might feel less safe if you ride in heavy traffic.
Programming doesn’t have to be rocket science, with Alltrax you’ll need a free download and a cord between the controller and your laptop, then it’s as simple as adjusting the volume on your radio.
Some other brands of controllers can be more complicated or require special programing tools, so it’s worth checking before you buy.

 

Sugested Parts List

It can be overwhelming, the basic Black Box Bikes electric motorcycle kit consists of hardware that allows a wide range of off the shelf golf cart and NEV motors to bolt on to your shaft drive Honda motorcycle frame, but what about the rest of the drive electronics?
You have a wide range of options, maybe too many options, to help give focus we’ve put together a short list of trusted companies that sell quality products, or  minimum specs you might want to look for.

 

Specifications

Many people at events want to know the specs on  the electric motorcycle that I bring along and the parts that were used to make a commuter bike on a reasonable budget.

Major Components:

Lithium Batteries: GBS brand,  sixteen 100 amp hour cells make up a 48 volt nominal pack, chemistry is LiFeMnPO4 pack weight is 112lb.

Speed Controller: Alltrax Axe4844   400 amp 48v, user programmable to adjust acceleration rate, throttle sensitivity, Max current, voltage cut off and a few other options.

Motor: Advanced DC Motor Series wound 36v/48v golf cart motor approximately 2.5/3.5hp continuous, around 20hp peek, top speed at 48v of 3,600 RPM, faster with a higher voltage.

Throttle: Magura electronic 0-5K twist throttle plugs directly into the speed controller.

Motor Adapter: Black Box Bikes kit connects the motor to the motorcycle frame and drive shaft.

Battery Charger: Elite Power Solutions 15amp battery charger with CANbus communication to the BMS.

Battery Management: Elite Power Solutions BMS with CAN bus communication.

12V Power: Surepower 10 amp DC-DC converter steps down the 48v pack voltage to 12v to run lights and other 12v needs.

Battery Disconnect: Albright 48v SW180 contactor connected to the key switch.

Top Speed: 60mph with the 48v pack, top speed is dependent on voltage, double the voltage and the speed doubles.

Range: 50 miles on open roads with a few stops, 35 miles in towns with stopping every few blocks, 100 to 150 watt hours per mile.

Weight: 440 Pounds, about 40-80 pounds below stock curb weight.

Cost: Total cost was $3,500 including the cost of the donor motorcycle.

 

The Kit

Our kit is the missing link DYI electric motorcycle builder wishes they had, it’s not only the brackets that hold the motor to the frame, but it also connects the motor to the rear drive wheel and it does it without wasting any space.

Our bracket kit bolts on to the frame using the same 3 bolts as the lower half of the engine, while the adapter shaft lines up perfectly with the swing arm’s drive shaft, 4 more bolts hold the motor securely in place.

It’s the best way to quickly start your project, and save money by eliminating the need to buy custom made sprockets or hiring a machine shop to make costly one off parts for you.

 

Batteries

Our goal is simple, to  help you build an awesome electric motorcycle, we don’t want to convince you that you need to buy batteries from us just so we can be a middle man.
As the electric car market grows the options of quality used EV batteries grows too, so Nissan Leaf, Chevy Volt and even a few Tesla S batteries are becoming more common on the used market, so if you are up for a good scavenger hunt you might luck out and find some used EV batteries that would work great on your motorcycle, if not then what we recommend is to seek out large format lithium batteries, such as those sold in the hobbyist market by GBS, Calb, or Winston Thunder Sky.

How many batteries can you pack on your bike? with most builds the CX500 frame can  handle about 150 pounds of battery weight on top of the weight of the motor, speed controller, battery box and peripherals while still being near the stock wet curb weight of the gasoline motorcycle.
Going above the stock curb weight is not advised, as the brakes and suspension would be pushed to their limits.

Options for batteries could even include spill proof sealed lead acid batteries, if you are simply looking for a low up front cost and can live with a range of 10 to 15 miles that lead acid might give, then lead acid batteries might be a worth while consideration.

Safety first! be sure you have a good understanding of the safety required before working with any battery pack of any voltage, batteries store a lot of energy and has the potential to do a great deal of damage or even kill if not handled carefully.

Motors

Our kit is designed to work with 19 spline golf cart and NEV (Neighborhood Electric Vehicle) Motors, so you have a wide range of used stock motors to choose from if you are on a budget, as well as a large selection of high performance motors that are available.
All of these motors are designed to be as compact as possible, freeing up valuable space on your motorcycle, while also bolting on with a common bolt pattern so you have used options from your local golf cart shop or NEV dealer, or dozens to choose from if you choose to shop around for something with even more power!

The two most common types of golf cart motor out there are Series Wound motors and SepEx motors.
With 3 Phase Brushless AC motors slowly gaining popularity, but are still somewhat rare.

Series Wound motors are one of the most powerful motors for their size and weight, they also tend to be low cost because they don’t use any rare earth magnets, the draw back is they do not support easy, cost effective regenerative braking.

SepEx or Shunt Wound motors are slightly less powerful then series wound motors, they tend to be low cost as well, their advantages include easy regenerative braking, simplified reversing by sending a signal to the speed controller and under light loads SepEx motors can be more efficient, leading to all around greater range with the same size battery pack.
The main draw back is that they are slightly less powerful with less peek torque from a dead stop.

AC 3 Phase motors are pretty new on vehicles even tho the motors have been around in factories for decades, the main reason is that AC motors that you want to vary the speed of require a speed controller that is also an alternating current inverter with a 3 phase output.
3 Phase motors tend to be some of the most efficient, many of the 3 phase speed controllers also offer regenerative braking, so if you want to get the most miles per charge they are a great choice, the biggest disadvantage is the motor and speed controller combination also tend to be the most expensive of any option.

Built On Experience

The Black Box Bikes electric motorcycle kit is years in the making.
With over 30 years of experience with renewable energy, almost 20 years of experience building and riding electric bicycles, 15 years of experience repairing, rebuilding and riding motorcycles, and 7 years of owning and rebuilding two vintage electric cars I thought life couldn’t get any better.
Then I took a friend’s electric motorcycle for a short ride where I quickly realized that none of the motorcycles I had in my collection came close to the thrill that comes with the quite, clean, swift acceleration of electric power, so I started out to build my own.

Having spent time in a machine shop I knew that making a few new pieces from scratch would lead to a more reliable, safer and cleaner looking machine compared cobbling pieces together. So I designed the brackets and couplings from the ground up to be solid and reliable while making sure they would be simple to bolt on to the stock motorcycle frame.

Now, Black Box Bikes can make it easy for you to build an electric motorcycle of your own and enjoy the silent ride.

Ryland Erdman

Menomonie, Wisconsin

The Long Story

Most home built electric motorcycles tend to follow two different paths.
One way is to build it with all off the shelf parts, some electric vehicle conversion companies sell a “kit” of off the shelf parts such as the motor, speed controller, battery cables, although those tend to be sold without a particular motorcycle in mind so you end up making or having someone else make custom mounting brackets and sprockets to make those parts work.
That gave way to two issues, the off the shelf parts didn’t always fit on the motorcycle and the custom parts were expensive one of a kind pieces of hardware,  leading to a high cost electric motorcycle or poor performance followed unless you start out with a huge budget.

The other path was scrounging parts, then modifying them by hammering, filing, bending and welding them until you get something that fits and works.
This route can work great other then the fact that replication is nearly impossible and the end result is as much a sculpture as it is a vehicle, while there have been some amazing motorcycles built in this fashion and they can be built on a limited budget they tend to take 100’s of hours to build that could have been spent riding.

A number of people I know have converted gasoline cars to electric on the cheap by using old forklift motors and I had to wonder if I could do the same thing with a motorcycle, after some searching locally and coming up short I started looking online, I figured I might start by just looking for a motor to see if I could base my search for a forklift off of a common motor that was the size that I could fit on a motorcycle.
My searches started turning up golf cart motors, the exact size of motor I was hoping to find and it turns out they are not only common, but they are cheap to buy used and they tend to be standardized with a lot of aftermarket options and even some  warehouse vehicles, factory service vehicles and Neighborhood Electric Vehicles (NEV) that are based off the golf cart platform but with much heavier components.
The more I researched the more I felt that a golf cart motor would be the perfect motor for a motorcycle because you could use a motor from a two person golf cart or a motor from an 8 passenger NEV depending  the performance you wanted.
Now, one complaint that seemed common with home built electric motorcycles was the motor was either too long and required modified foot pegs to give a wider stance or when a short compact motor was used that was not powerful enough.
I never liked the noise that chains made on electric motorcycles and I liked the clean, enclosed design that shaft drive motorcycles have, a shaft drive also meant that it wouldn’t matter how long the motor was, then I thought back to my time working in a motorcycle repair shop where I saw a handful of Honda CX500 motorcycles come in and I was always impressed by their styling and that they were always well cared for.
The CX500 has a water cooled V-twin engine that was designed for light touring, a fantastic bike for it’s day but with a fatal design flaw, the water pump is above the alternator, over time the rubber seals crack or wear out and coolant leaks, if this persists it drips in to the electronics where it causes additional problems, the first step in replacing this small, inexpensive seal is to remove the whole engine, it’s at this point where many motorcycles owners choose not to have it fixed.
The CX500 is an interesting design, the engine is a stressed part of the frame, so when you remove the engine there is no down tube (the frame tube next to the front tire) it’s also designed for a faring and saddle bags, so it has the brakes and frame to handle some extra weight.

When I started telling friends about my desire to build an electric motorcycle I would hear stories about some neighbor or uncle who was an electrical engineer who I should meet because they had dreams of building an electric motorcycle too.
I’ve been building and working on electric vehicles for years and I’m not an electrical engineer and I don’t need to be; all of the components are well engineered already with very nice, clearly labeled wiring diagrams that take the guess work out of connecting it all together.
All I have to do is buy off-the shelf components and connect them together as the manufacturer instructed.

So, now I found a common, cheap motor that has been industry proven, I found a high quality motorcycle  that doesn’t cost much to buy used, the electronics are all off the shelf, I just need to connect it all together pack them in to a motorcycle frame and ride it down the road, right?
At that point I realized I would be in the same place I would be if I paid thousands and ordered an electric motorcycle kit from an electric car conversion company.
So I developed and built the Black Box Bikes kit;  a kit that takes these common, low cost used parts and common off the shelf parts and connects them to a motorcycle frame without cutting or welding it, by bolting everything together you should be able to build your own electric motorcycle in a weekend.

Now, Black Box Bikes can make it easy for you to build an electric motorcycle of your own and enjoy the silent ride.

Ryland Erdman

Menomonie, Wisconsin