An EV conversion is an Internal combustion engine car (ICE for short) that has its engine, exhaust and fuel tank removed and replaced with an electric motor to drive the wheels and batteries to power it.
You need a controller to adjust the power of the electric motor faster and slower or more simply on and off. Up to date conversions using an AC motor will need an inverter to change the electric battery power from Direct Current (DC) to Alternating Current (AC) to drive the motor. A charger is needed to replace the energy consumed by the batteries. The charger will need a charging port to connect to the energy source that will replenish the batteries electricity, for example a household plug (3 KW) or something more powerful like a wall charger (7 KW).
There are lots of different types of EV conversions with some using DC motors instead of AC, please check the motors section for detail on this. There are various types of batteries you can use, for example in early conversions lead batteries are fitted, more recently Lithium batteries are now becoming increasingly common as prices come down. Lithium batteries are better as they weigh much less, are smaller in size and more energy dense. You will hear the term energy density used quite a bit, this basically means the level of power for the size. The higher the energy density of a battery the better. Space tends to be a big factor on range and power when it comes to EV conversions, as ICE cars are not built with batteries in mind this can make fitting all the batteries you need or want a struggle.
With regards to power the higher the voltage the more power a car can have.
The Speed, pack KWh rating, driving conditions, aerodynamics, vehicle weight, terrain, climate, driving styles all play a factor in distance.
An EV conversion can be as simple as the video below which made me laugh when I watched it. I wonder what the range and the top speed is?!