Components
The basic design concept used the frame of a gas powered motorcycle. The motor and transmission from the old motorcycle was removed and replaced with an electric motor and batteries. A direct drive system was used to replace the transmission.
Bike
Suzuki 1974 GT750
Motorcycle Selection: The desired motorcycle chassis had to meet the following specifications:
- Large Engine to provide ample space for batteries and electric motor
- Steel frame for ease of modification
- Lowest possible weight
- Rear sprocket
- Operation brakes
- Good tires and suspension
- No damage to the frame
- Low cost
The motorcycle chassis chosen was a 1974 Suzuki GT750 purchased from Lemon and Barrett’s in Mineral Wells, WV. The GT750 had a 738 cc, 3 cylinder 2 stroke engine. The large engine created an ideal amount of space for an electric motor and four 12 volt batteries. Unfortunately the motorcycle had a very heavy frame compared to some of the other motorcycles that were considered. Another deciding factor was the steel frame. This made welding other components to the frame easier. The price also made it attractive at only $250.
Motor
Briggs and Stratton Etek-R
Model EMC-R
8 HP - Continous
15 HP - Peak
160 In-lb Torque
The electric motor kit selected for the design was a Briggs and Stratton E-Tek R. The E-Tek R is a 48 volt electric motor. It delivers a peak horsepower of 15 HP and 8 continuous HP. Also, a Magura twist grip throttle, wire kit, and a 250 amp fuse were purchased. The cost of the motor kit was $1075 and was ordered from electricmotorsport.com.
Controller
Alltrax 4834
Input: 24-48 volt
Current: 300 Continous amps
Batteries
48 Volt System
4 - BB Batteries
Model EB50-12
The desired specifications for the battery were as follows:
- Deep cycle batteries
- 12 volts for 48 total volts
- High amp hours
- light weight
- Compact size
- Reasonably priced
Four EB50-12 batteries, manufactured by B.B. Batteries,
were selected for the power source. The batteries are 12 V batteries and weigh in at 36.4 lbs each. The EB50-12 has an amp hour (Ah) rating of 50 Ah. The EB50-12 battery is lighter and smaller than a typical 12 V car battery that was
originally considered. The cost for one battery was $145.
The battery charger purchased for the project was a 48 V, 4 amp charger produced by Soneil. This charging system will charge fully discharged batteries in eleven hours.
Contactor
White Rogers 12-4T
Coil Voltage: 12 VDC
Rated Voltage: 12 VDC
Continuous Current: 200 amps
Fault Current: 1000 amps
Throttle
Magura Twist Grip 0-5k