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Discussion Starter · #1 ·
Hi there!

I have a few basic questions about building an EV. Ive been reading up on the forum, but I can't help but feel im missing the picture.

How do you make an electric car function, beyond just mounting the motor to the drivetrain? Ive heard about controllers, are these connected to the car's accelerator pedal, and so give the motor current when the pedal is pressed?

What is a controller, what function does it serve, and what inputs does it receive and from where to allow the EV to move/function?

Is an EV conversion, in terms of merely having a moving vehicle, the replacement of an ICE with an electric motor, and a controller to control it, as well as a battery/ power source?

Thanks!
 

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Here are some basic answers to your questions:

1. In short, yes. Once the motor is mechanically connected then you need to control the motor which is done by a motor controller and yes it takes a throttle input. The motor controller needs to be of the same type as the motor DC or brushless or whatever and also needs to be rated to the voltage and amperage you plan on running.

2. A controller controls the speed and direction of the electric motor. It needs throttle signal input and input DC voltage from a battery at minimum.

3. Yes that is the basics of it.
 

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Discussion Starter · #3 ·
What other parts are needed to convert a donor car to an EV, besides the controller, throttle potentiometer, the battery, BMS, and the motor?
Do I need a separate component for charging? Is there a universal charger that exists?
 

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What other parts are needed to convert a donor car to an EV, besides the controller, throttle potentiometer, the battery, BMS, and the motor?
  • You have a contactor which completes the high voltage circuit once the key is turned.
  • There's also a vacuum pump which creates a vacuum for your brakes since that vacuum was previously created by your engine, which you don't have anymore.
  • A shunt is connected to the high voltage circuit and resists some of the current to the voltmeter and ammeter (like a JLD404) which displays how much current and voltage is flowing through your system.
  • An inertia switch cuts power to the car on impact, like in an accident, so that your car doesn't just keep moving after an accident
  • A DC converter converts the high voltage from the main batteries down to about 12 volts to charge your 12V accessory battery, much like an alternator does
  • And then you have fuses and a circuit breaker to protect your important components like your controller and batteries from being blown if the current/voltage spikes too high potentially damaging important parts in your system
Do I need a separate component for charging? Is there a universal charger that exists?
Yes, you will need an onboard charger to convert the AC voltage to DC and to also stop charging the batteries once they have fully charged. A J1772 charger and port is pretty universal but some chargers will require an AVC2 or AVC2.r board (the only difference in these boards is that one has an internal resistor and the other doesn't, so you'll have to match the board with the resistor (AVC2.r) with the J1772 port that doesn't have a resistor and vice versa). This board basically communicates with the onboard charger to know to start charging.
 
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