bike

The Electric Motorcycle
Everything you wanted to know about building an EV Motorcycle

Step 4: Parts!
The Motor kit: Electric Motorsport

It includes most of what you will need to build your bike less batteries. The Schematic that comes with the Alltrax controller will be close to what you need. I have included my version of what an EV motorcycle should have for wiring. The DC to DC converter can be replaced by a small battery if needed.
Motorcycle Wiring

I priced the parts separately but getting a kit still a better deal.

The kit comes with:
A newly developed Mars "ETEK" RT Motor (Permanent Magnet Motor)
Alltrax AXE 7234 controller
Magura twist grip throttle 0 to 5K
Contactor, Wire kit, Fuse and holder.

This set up was designed for the best performance at 72 volts. (6 Batteries) You can run it at 48 volts, but your top speed will suffer. We wanted 55 MPH when needed. Most of what we will see will be in the 45 MPH range.

Motor:

The motor itself is the heart of the bike. There are several types out there.  There are some really cheap versions on EBAY and in most cases not worth putting on your ride. The latest version of the Etek R and RT motors are the best bang for the buck. The “R” version is a high RPM motor and will do great if you have a really light bike. The “RT” is a torque motor and since this is a around town bike carrying both of us we chose that one.

Batteries:

Here is where the rubber meets the road, sort of. The choice of batteries will dictate how well the bike will perform and last (MPC? Miles per charge).

The type and performance of batteries:

  • Wet cell: Lowest cost and performance.
    Gel cell (Optima): Better, but heavy and large, higher cost
    Dry cell (Odyssey): Smaller and has really good reserve capacity. Same cost (even cheaper from Summit Racing) than Optima.
    Lithium: Best choice as they are light weight, has thousands of charge cycles, but at this time, very expensive.

We went with the Odyssey Dry cell, 925. (as in 925 CCA!) We ordered 6 of them from Summit racing and since they are a dry cell, no issues shipping them via Fed EX.
Two days later they were at our door.

We had used this 23 pound battery on our supercharged dragster. It had no issues running all day with out a charge from an alternator or external charger. These batteries do require a slightly different charge voltage.  A Schumacher “Ship and shore” charger met all of the voltage numbers required for long battery life. You can use any charger, but we wanted to get the maximum out of these batteries. This charger was fairly cheap to purchase. Charging these types of batteries is best done one at a time but running a 72 volt charger will work too.

Battery Cables:

Our kit came with enough 6 gauge cable for this project. The cable was the soft wound type which is more flexible and much easier to work than standard car battery cable found at your local auto parts store.
 
Chain and sprockets:

The bike uses direct drive. No clutch is needed. The ratio on a regular bike is about 2.5 to 1 (shown sometimes as 2.5:1).  An electric bike should really have between a 4:1 and 5:1. This means a 5:1 will have 10 teeth on the front and 50 on the back. Any combination of teeth that get you there is fine. If you have a torque motor and want high speed, you will be more toward the 4:1 range. We wanted 55 MPH at times, but 45 MPH was the main speed. We have an 11 on front and a 48 on the back giving us a ratio of 4.3:1.  

 This is a motorcycle, so do not use a go cart chain. A 420, 520 or 530 chain will work great. The front gear for an electric motor is cut a bit different, more for industrial use. We were advised to purchase industrial chain and found out it was much cheaper than the $100 + motorcycle chain. Since the only noise you hear is the chain, I am not sure it is any quieter than the standard motorcycle chain. If I get to test both I will report on that later.

The Voltmeter:

The electronic “Gas” gauge.  A LCD meter works with very little power consumption and can be seen in the day or night if you get a lighted version. Ours was a new unit and ran $24 from a company on EBAY.
I recommend getting one that measures the total voltage of your project, not just one battery.    Link 10 makes a meter that measures volts, amps, amp hours consumed and operating time remaining. The Link 10 allows you to select Automatic, Sleep and Scanning modes and calculate and display charging efficiency. It is all on how much information you want.

Step 5


The required disclaimer: This information is about what we learned on our project and is not intended to do anything but show you how we did ours. LEARN all you can before starting any project with this much voltage.  A 9 volt battery, applied correctly, can kill you. Think about what 6 - 12 volt car batteries can do if not wired correctly.

If you feel that this page helped you save time,
effort and hopefully money, please let me know.

If you have any questions or
suggestions, please contact me!