Fossil fuel-powered cars may have reached their peak and may soon be only used in marginal areas like deserts. This is because the United Kingdom/ Europe plans not to have any fossil fuel vehicle being sold there by 2025-2030, it may seem a long way ahead, but is it?
Most Africans buy secondhand cars from Japan or Europe, but 2025 might be the last year to get polluting cars. I must add that if the generation of power is done using coal, you’d rather get a guzzler (not literally), but ironically mining of lithium which is a critical part of the battery also destroys the environment. So pragmatically, there is a balance to strike there, however, despite the damaging effects of mining lithium, the emissions here are minimal compared to petrol/ diesel-powered cars.
So, if you are a tree hugger like me, have the dexterity mechanically, and you love to learn, this is a guide to convert your vehicle to using electricity as the prime mover. This guide is relevant whether your car is a Mercedes Benz S63 or a Ford Model T or a bus.
An EV system comprises a motor, controller, gearbox, and batteries. This may sound simple, but we haven’t even scratched the surface yet. So, let us start from the beginning, a car needs a prime mover i.e. Engine or motor, the ability to steer, brake, and lights, and have comfortable features.
The first check we need to do is to check if the Anti-Lock Braking System and the power steering in your car are purely electric, if they are, we can start. If they are not, we need to find compatible parts to replace these so that we have predictable performance.
When choosing a motor to move the car we must consider;
- The weight of the car and how much horsepower we want the car to have depending on the number of passengers or luggage to be hauled.
A bus would have a powerful motor as it ferries 40-50 people plus luggage, a small car however can have a motor of 50-120 horsepower. A sports car designed for speed might have 150-300 horsepower, or even a configuration having more than one motor. Once we have decided on the motor and how many motors, we might need to go to the next stage to consider the battery.
There also exist double motors that can connect to each axel in the front or the rear offering high and immediate torque unlike a Petrol or diesel engine.
When designing electric vehicles, it is important to note that when choosing the battery pack the longer the range the bigger and heavier the battery. It is a trade-off between weight and range; technologically batteries are improving and getting better year by year.
- The best battery is the one that can handle your daily commute and periodic travels, the minimum battery range recommended is 100 miles
Electric vehicle batteries help make the car stable as they are located at the base of the chassis. Lithium batteries are chosen to be used by electric vehicles because of their high energy density compared to their weight. It is an advantage to convert light cars to be electric vehicles as battery packs may be very heavy, consider the case of the Tesla Roadster where its batteries weigh 482 kilograms.
After successfully choosing a motor and battery we need a controller.
The controller is used to input power from the batteries to the motor, the accelerator pedal in an electric car is holed to a rheostat (variable resistor) which provides a signal to the controller whether to provide full speed current or to just slow down. The batteries in electric cars store power as Direct Current, the controller therefore has a DC to Alternating Current AC converter as the motors used are alternating current motors.
- DC motors can be used, however one of the drawbacks of these motors is that they are expensive to maintain, and they are more expensive to buy. However, you can still make an electric vehicle using a DC motor but for this article I will be using an AC motor.
The controller receives DC power from the batteries which is then converted to 3 phase AC power the transmitted to the AC motor using large transistors which switch on and off rhythmically to produce a Sine wave. With the motor powered and a signal from the gear box, the car can now accelerate depending on the resistance on the rheostat.
A charging system is also needed to replenish spent energy from the batteries and to monitor the battery condition when charging to reduce the risk of damage while charging. A well-designed charging system will examine certain metrics to minimize charging time while at the same time monitor batteries (the metrics are battery temperature, voltage and flow of current).
Now, remove engine, clutch, fuel tank, exhaust and radiator. Attach adapter plate and mount motor using custom mountings, on transmission, pin gear 2 to offer gear reduction to ensure smooth driving at start up. Mount batteries on the lowest part of the car and install carefully to ensure no cells are damaged, also mount controller at this point. Connect air conditioning, ABS systems, power steering and vacuum pump for brakes to the electrical system in the car. Install a small DC to DC converter to low run some utilities in the car to reduce dependence on the batteries. At this point you connect the batteries to the controller using the welding cable and install the charging system and install it correctly. Install a rheostat and connect it to the accelerator and rewire the ignition switch to the contactor that starts the car with almost no sound.
If you follow all these steps now you have your own electric vehicle with so much torque and fun to drive and the exact opposite of a loud exhaust Subaru!
Author: Sam Ndegwa
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