I finalized the powertrain design, and purchased and received the major EV components. With my design and component selection I should be able to achieve my riding goals:

1. Ride at speeds between 35-50mph (55-80kph) for sixty miles (100km). all of
2. Have good acceleration from traffic lights and stop signs.
3. Maintain or slightly exceed posted speeds going uphill.
4. “Punch it” and occasionally ride at 60 mph (100kph) for a few miles at a time.
   

The Major Components:

EV’s have relatively few components compared to traditional internal combustion engines (also referred to as “ICE” in the EV world). Here are the most important components and how they are related to each other:

The Battery sends power through a Controller that sends commands to tell the Motors what to do. It will slide into this spot I have made in the frame:

Let’s look at each component:

Battery

I’m using 72-volt Li-ion with a capacity of 6.3kw and a continuous amperage of 380 amps. I’m going to explain each of the numbers.

• Voltage: The higher the voltage the higher your potential speed. If you want to go 100kph on a bike you need 72 volts. Lower voltages provide less speed, and more volts (to a point) will give you more speed. For example, a golf cart runs at 48 volts and a Tesla runs at 400 volts.
• Capacity of a battery is like the size of your fuel tank. Here’s an example of what I’m talking about: I have a Heinkel Kabine Microcar EV that consumes an average of 100 watts of electricity per mile of driving. With a 6.3kw battery (6,336-watt hours to be precise) I should be able to drive 63.36 miles. Since my scooter will weigh half of what my car weighs, I should be able to go further (although I won’t know exactly until I drive it, and there’s no one to ask yet).
• Continuous Amps: Amperage flow is like water pressure. The higher the amps the more force you have available to propel yourself.

Here’s a picture of the battery. It’s a beast and weighs 80 pounds!

It will slide into this area in the frame:

The Controller

The Controller is the brain that tells the motor what to do. You will connect the throttle to it (among other things) and then you set parameters to tell the scooter how to behave. tell it how you want your scooter to behave. Setting parameters is like kitting your bike with software instead of carbs or expansion chambers. Do you want acceleration like a jet plane (“logarithmic” acceleration)? You can do that. Want to have a reverse “gear” on your scooter? Sure, no problem. You get the idea. The important things about the controller are that it’s matched to the voltage (72 volts in my case) and can handle the amperage that the battery can send though it. I’m using a Fardriver 72680 controller, which can handle 72 volts and 680 amps.

If you are in Europe: The controller you use is important because some countries certify your build based on the controller you’re using (I’m told that is how Germany does it).

The Hub Motor

I’m using a QS-Motor QS260 5000 watt (5kw) 12” hub motor with the same tire as a modern Vespa GTS scooter. According to the specs I should be able to achieve 110 kph with this motor. The key considerations when choosing the motor are the combination rim/tire height, and the amount of power the motor can provide. I selected 5kw because I could get a 12” rim and a little more “oomph”. 5kw is probably more than I need, but the “there’s no replacement for displacement” rule applies to hub motors as well as internal combustion engines. I’d rather have the capacity when I need it.

Some Other Components Worth Mentioning:

There’s a few more components in the mix worth mentioning.

One is the DC-to-DC converter. This lets you run 12-volt lights, etc. from the 72-volt EV system. The important feature here is the controller I’m using is “fully isolated”, which reduces the chance of high voltage shocks or surges from impacting me or the rest of the bike. “Fully Isolated” means the high and low voltage circuits are completely isolated from each other.