Electric Vehicle Frequently Asked Questions

BUILDING A CONVERSION

How much does it cost to convert an ICE to EV?

Conversions have been done for less than 5000USD, but that is not the norm. As with many aspects of conversion, what you want from the vehicle affects the cost.

A high performance EV needs a controller that can put a lot of amps into the motor for high torque, and a high voltage battery pack for high speed. The need for high current leads to the selection of advanced AGM batteries, which in turn drives the requirement for sophisticated charging and battery balancing technology. Each of these selections drives up the cost.

An EV for everyday use runs the middle of the road. Depending once again on how many features are designed into it, these conversions can cost from 6000 to 10,000 not including the cost of the base vehicle.

If you are just getting into EV's and want to get your feet wet without spending a lot of money, consider buying a used conversion. Usually these are much less expensive (and a lot less work) than doing a conversion right off the bat. Check out the EV tradin' post for used EV's. A used EV can be a great learning experience for those who may not be sure what they want in an EV, and do not know if they want to do a full-up conversion themselves right away.

How do I choose the best car to convert?

This depends largely on what you expect to get out of the vehicle. If you want range above all else, the ability to carry a lot of batteries is an overriding concern, so you would look for a vehicle with a lot of carrying capacity. If performance is your ultimate goal, then a light, aerodynamic vehicle with a high performance suspension would fit the bill best. Some converters combine both of these, and have a motto "less iron and more lead". This is fine, but I speak from experience when I say that a unibody can and does bend over time. This can lead to being permanently out of alignment, with resulting added drag, abnormal tire wear, etc. It is important to make sure that every aspect of the base vehicle can handle the added weight.

The most overriding guideline is to go with a vehicle you really like. Otherwise, you will wind up with an EV you don't care too much for after the uniqueness has worn off. EV owners tend to keep their vehicles a relatively long time, so you want a car you will be happy driving well into the future.

In general, look for a lightweight, relatively aerodynamic vehicle with a high gross vehicle weight rating as compared to the actual weight.

There are many other things to consider besides this, and they are covered in the free technical paper "Choosing a car to convert" available from Bob Batson at Electric Vehicles of America.

How can I build a very fast/quick EV?

If performance is your goal, then your general design guidelines are going to include the following:

1. Start with a small, light, high performance donor vehicle, preferably one that you can get performance suspension parts and brakes for.
2. Choose a controller that can deliver lots of amps to the motor (more amps equals more torque).
3. If using lead-acid batteries, use sealed (AGM style) batteries. This type can deliver high currents more easily than flooded batteries with less capacity loss at higher currents.
4. Choose a battery capacity that is close to what you need with minimal reserves. This will minimize the weight of your battery pack.
5. Use a high voltage (> 120V) battery pack for higher speeds at lower currents. The newest "everyday" controllers will let you use packs of up to 300V nominal. The highest performance EV's use pack voltages of 240 volts and up, with 2000 amp controllers!
5. Don't forget to switch to higher performance brake components, so you can stop just as quickly.

How can I build an electric motorcycle?

The same way you build a car, only smaller.

The basic parts are the same: Batteries, a motor, and motor control. The specifics are different. Magura makes a nice, if expensive, twist grip throttle that uses a 5 kilo-ohm potentiometer which is a pretty standard value for scooter and some larger motor controllers. Batteries can be whatever you want, from flooded (wet) lead acid to sealed AGM lead-acid, nickel cadmium or nickel metal hydride. A small, light battery made of more exotic batteries is easier to afford on a motorcycle than a car. A charger is still needed, and the more costly the batteries, the more you want a charger that won't damage the batteries. Just like in a car.

Motors are the one place where motorcycles can be found to be different. While DC conversion cars tend to use series wound brushed DC motors almost exclusively, brushed permanent magnet motors, brushless permanent magnet (synchronous) and series wound motors can all be found on motorcycles. Brushless DC and brush permanent magnet motors are less common on car sized EVs often due to cost (brushless motors usually have expensive and strong magnets) or inadequate power (brush permanent magnet with less powerful and less expensive magnets). But on a lighter motorcycle they might be just fine.

3 phase AC (asynchronous) motors are not common, on motorcycles likely due to inefficiency at such a small (motorcycle) size and the fact that most AC controllers use high voltage which means lots of batteries. That being said, there is no reason that you can't use any of these motors,they just involve tradeoffs. A larger motorcycle perhaps with a sidecar could have 336V of batteries and an AC induction drive, and some minibikes run car starter motors at low voltage (24-48V) and high current.

Motor controllers must match the motor. There may be a few more controllers available to the EV motorcycle crowd because the power requirement is a bit lower and things like forklift or golf car controllers that might be marginal on a car could be just fine on a motorcycle.

Once all the drive parts are collected, then the power transmission needs to be figured out. Luckily chains are relatively inexpensive and parts can be purchased or adapted easily, be it from bicycles or sporty motorcycles. Custom sprocket sizes are fairly common on motorcycles (try sprocketspecialists.com). Others use a friction drive on the rear tire, like the EV Warrior bike. More powerful motorcycles will likely want older motorcycle frames, chains, series wound motors and low voltage (36-48) controllers.

Some people prefer belt drives, which can be quieter and have good efficiency. A Gates Polychain GT belt is a relatively common choice and there is extensive engineering information on the Gates website.

Brakes are important as the conversion will weigh more than the original motorcycle. Most motorcycles have good brakes stock, but bicycle to light motorcycle conversions should consider at least mountain bike disc brakes. And good tires. The "Hookworm" or other "baldy" mountain bike tire will be acceptable on the road. Motorcycle conversions again have less to worry about in this department.

If you want it to be a real motorcycle then it will have to conform with the local and Federal laws. This is easiest to do if you started with a motorcycle and kept the lights, horn, turn signals and such. You may consider low power versions of these components. Often, LED lamps that fit in existing lamp holders are available and they offer better reliability as well as saving the energy to propel you down the road.

Finally, places like the EV discussion list [ http://www.madkatz.com/ev/evlist.html ] or the Yahoo power-assist group [ http://groups.yahoo.com/group/power-assist/ ] have information on EVs and human power assist (EV and ICE) respectively

How can I build an electric scooter?

This question has not yet been answered.

How can I build an electric lawn mower?

A lawnmower is an excellent choice for a conversion, since the small engines they use typically pollute far more per gallon of gas used than a car engine. There is also the benefit of being able to mow early or late when it is still cool out without disturbing your neighbors.

There are as many ways to do this as there are different kinds of mowers out there. I discuss push mowers here. In general, the more like a tractor the mower is, the more like a regular EV conversion it will be, both in complexity and expense.

If you are comfortable using a motor with a cord, the expenses are minimal, and the installation is simple. In this configuration, use a standard AC motor of the appropriate HP rating (usually 1-2 HP) in place of the ICE motor. Make sure the motor is rated for outdoor use (enclosed) and is properly cooled. Motors are available from tool warehouses, motor repair shops, motor distributors (look in the yelow pages), and some home stores. Sometimes you will have to have a machine shop machine a special adapter to attach the blade to the motor shaft, but usually these modifications are minimal. Safety items include a switch rated for the appropriate voltage and amperage, and a fuse or circuit breaker. A second switch should be incorporated to automatically open when you take your hands off of the handle, like the ICE cutoff lever on most newer mowers. This can be done by attaching a momentary contact switch of the appropriate rating to the existing ICE dead-man handle. The only difference is that when you grab the handle again after shutting down for a moment, the motor will start up without having to yank on a rope. Of course, you should keep all the guards and safety items already on the mower.

If you want to go cordless, then you have to add provisions for battery mounting to the mower, and use either a DC motor or a properly sized inverter. The DC motor should be of the shunt or permanent magnet variety, because a tendency to seek a constant speed is the preferable mode of operation for a mower blade. Usually, DC motors are a little more expensive than AC, and DC switches can be harder to find. A charger must also be provided, though for a push mower, an external charger makes more sense than an onboard.

For exciting developments in production EV mower technology, visit www.zeromow.com!