December 23, 2020
Before electric cars started rolling out of the assembly lines of auto giants and electric vehicle (EV) start-ups, enthusiasts of green energy have been modifying existing internal combustion engine cars to run entirely on batteries to achieve energy efficiencies which IC engines cars cannot even dream of. A steep decline in the costs of batteries over the last decade and improved technology of motors have made it possible to convert old cars into EVs that outperform their predecessors both in terms of power and mileage. Given the necessary financial resources and some technical expertise, it is theoretically possible to convert any IC engine car to an EV!
Basically, the conversion to an EV from an existing IC engine car requires removing the engine from the car and all the other associated hardware such as fuel tank, exhaust, muffler, starter and the radiator. The gearbox or the drive train needs to be kept in place, and modifications are required for power steering, hydraulics, air conditioning and heating systems. In place of the IC engine goes a powerful DC or AC motor that’s capable of matching the engine and a simple set up of electronic components required to run the motor and charge the batteries. To power, the motor a series of batteries need to be stacked in the form of a battery pack in the car.
There are two ways to go about converting an IC engine car to electric. The first is to compute power requirements and battery capacity based on the driving speeds, the weight of the car and the desired range to order components that match the requirements. The second way is to buy custom kits that are tailored to specific car models or universal kits that can be installed on a wide range of car models. Custom electric kits come with all the essential components that only need to be installed into the vehicle while universal kits require some components to be fabricated by the builder such as battery boxes, motor mounts etc.
Here is a more detailed breakdown of what goes into the conversion of an IC engine car to an EV:
Taking apart the donor car
As mentioned earlier, any car can be converted into electric; however, if a new “donor car” needs to be purchased to convert it into an EV it’s best to choose one that comes with a manual transmission, lightweight construction and a decently aerodynamic body. Anything related to the IC engine systems and redundant components that add excess weight should be taken out. That means the engine, fuel tank, exhaust, starter, radiator, coolant systems, fuel lines and filters.
Electric Motor Installation
That engine shaft that supplies power to the transmission is replaced with the motor shaft. To do that there are two things that need to be done. First, the motor needs to securely attach to the transmission using an adapter plate which has to align the motor with the transmission perfectly. Second, a strong coupling needs to be machined out of existing parts such as the clutch plate to accommodate the motor shaft. Since there will be no shifting of gears, the transmission will be pinned to the second or third gear. There are both induction (AC) and DC motors available for use in EV with a range of torque and power to choose from. Both the motors lend themselves to regenerative breaking and can be used in EV conversion projects looking for the maximum efficiency.
A motor controller is an electronics package that goes in between the batteries and the motor to regulate the amount of energy going into the motor. Without the controller, there will be significant power wasted as heat when the EV is running at slow speeds. Many of the motor controllers lately also feature a supporting system for regenerative breaking where some of the energy is recovered when the vehicle decelerates to charge the batteries.
The batteries are the most significant component of any EV as they determine the range, weight and power available for the vehicle. There are several battery options to choose from based on budget constraints and power requirements. Many EVs use the nickel-metal hydride (NiMH) batteries as they balance costs, power output, range and weight quite well. The lithium-ion batteries are close to ideal due to their lightweight, large energy density and 2000+ charging cycle life; however, they are costly and out of range of most conversion budgets. Lead-acid batteries are also conventional for conversions, but they are inferior compared to NiMH and Li-ion batteries. To charge the batteries, a DC charger will have to be built into the car that can vary the charging rate based on the state of the battery. It should also be able to accept varying AC inputs to make it versatile and usable wherever one may choose to charge the batteries.
Gages for monitoring speed and batteries
A voltmeter and ammeter is all that’s needed to monitor the start of charge and the current drawn out of the batteries during operation. The voltmeter is similar to the fuel gauge in an IC engine car, and the ammeter gives an idea of how quickly the batteries are being drained. A digital speedometer can be attached to the wheel to display the speed of the vehicle in any unit.
Typically a 12v system run by a separate battery is maintained to operate the headlights and other instruments such as the heating components, radio and power windows in the EV.
To conclude, given the budget and the availability of components, it’s possible to convert any existing IC engine car into an electric vehicle.