The Battery Pack

After much investigation I have come to the conclusion that lithium rechargeable battery's are the battery of choice. They are the best value for money in terms of power to weight ratio. I have to keep the bike somewhere in the original weight range to get it registered, and i also want the bike to have as great a range as possible with the latest technology available. I am looking a making a battery pack consisting of 40 3.2V 40A lithium battery's that weight about 1.5kg each. So that gives me a total battery pack with a nominal voltage of 128V at 40A and a weight of 60kg. This works out to be a ~5kw battery pack. So it should run the 3kw motor for at least 1.5 hours.

I am going to make 40 fake batteries of the same dimensions that i am looking at using to make sure i can physically fit them in the bike. I have the leftover room where the electric motor is and petrol motor was, i also have some room up front near the headlight that I may be able to squeeze a few in and also where the air-cleaner was and of course under the seat where the petrol tank used to be. I also have to be careful to leave enough room for the battery charger and motor inverter.

3-Phase Motor

I have now got the electric motor. It is a 3-phase induction motor by CMG. I have had a cog machined up to fit onto the shaft of the motor. The motor will sit in the frame with the cog slightly forward of the original gearbox output, so i have to extend the chain by 3 links. I have had some motor mounting brackets made but they need some modification (the chain sits on the swingarm at the moment).

The motor is designed to take 380V-415v at 50Hz in star configuration. It is a 4-Pole motor and the speed of the motor when supplied with this is ~1425RPM at 82% efficiency. I am looking at running the motor in delta configuration which is 220V-240V at 50Hz, the efficiency is still 82%. Because the motor is actually 4-pole. I should be able to hopefully (this depends on how the motor is wound) make a modification inside to change the poles so that instead of in serial they are parallel. This will then bring the motor voltage into the 110V-120V range. Which is about the voltage of the battery pack that I'm planning on using. If i can do this it will simplify the inverter design.

I have also painted and fitted the mirrors.

1990 Suzuki Across

I found a 1990 Suzuki Across at a wreckers, I bought the complete bike minus engine for $800. It had been dropped with most of the damage being done to the front panels. It needed a good going over and a new paint job (the picture left is after the panel repair and respray, its not all together yet).

The original colour was black with a metallic fleck through it. I think the new paint will make it standout a bit more. I am also replacing the screws that hold the panels on with stainless steel allen key screws.

I cleaned up the frame and touched up the paint. Also recovered the seat.

There is heaps of room where the engine and petrol tank was for the electric motor, batteries and controllers.

Choosing a bike

There were many factors to consider when choosing the motorcycle to convert. The major factors were:

• Cost
• Aerodynamics (better airflow=more efficient)
• Weight (less energy to accelerate)
• Appearance
• Ease of conversion

After taking these factor into consideration the ideal bike to convert was the Suzuki Across. They are classed as sports-touring. The Across is fully faired so the aerodynamics are pretty good (at worst they are better than a cruiser), also the conversion can be hidden underneath the fairings with the main thing to distinguish it as different would be the absence of the tailpipe.

The bike is relatively light weighing in at 160kg dry according to spec sheet. The Bike is big enough that i would be comfortable riding it (I'm 6" tall). They are getting old now so they are cheap to buy and get parts for.

The other big advantage to the Suzuki Across is where the petrol tank is on a normal bike the Across has a boot big enough to fit a large helmet, and the petrol tank is under the set. This is perfect for the electric motorcycle because the unused petrol tank can be removed without affecting the look of the bike.

Project Aims

The aims of the Open Electric Motorcycle Project are to take an existing motorcycle and to convert it to be an electric vehicle, this bike is then going to be registered and use for daily commuting.

Using an existing motorcycle eliminates the need to design and engineer a complete bike. Only the electric motor brackets and battery pack will be need to be engineered for registration. The time in building a bike from scratch takes a lot of time and resources too.

• A range of at least 100 kilometers is required.
• A top speed of at least 100kph is required.
• All schematics and software for the battery management and motor control are released as open source.