Electric Car Voltage and Power Requirements

by Aaron
(CA)



Why do people us 6v batteries in their electric cars and not 12v or 24v? And what are the average power requirements for the average motor that is used in a converted electric vehicle?

Hi, Aaron -
In DC electric car conversions, with very simple inexpensive controllers, 6v batteries conserve battery power better than higher voltage batteries, so your range ends up being longer with 6v batteries.

In AC EV conversions, 12 volt batteries are more common.

As for 24 volt batteries, I've never seen them.

Power requirements?
People tend to put at least 120 volt systems in their medium sized cars. (A small car like a VW Bug or a Geo Metro can get by with a 72 or 96 volt system, but it's not going to be a tire-burner; )

As for amp-hours...there's a trade-off. The more amp-hours a battery has, the longer it can run your car, but the heavier it will be. There's a sweet spot, generally somewhere around 200 amp hours, that most people use.

Regards,
Lynne



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Battery voltage
by: Anonymous

There's always a trade-off between voltage and current in a battery. A 6 volt battery typically has bigger cells than a 12 volt battery. Bigger cells can provide a higher current than smaller cells or a given current longer than smaller cells can.
The cell voltage of a battery depends on it's chemistry. A lead acid car battery provides a nominal 2 volts. A 6 volt batter is simply a group of three 2 volt cells tied together. A 12 volt battery is a group of six 2 volt cells.
I have seen a 24 volt battery. I was simply a group of twelve 2 volt cells. It came out of a ship.
A battery will typically do better when the current is kept lower than when it is higher. A slower drain is easier on most batteries.
Modern electric vehicles will typically use a higher voltage and lower current. The Prius, for example, has a drive voltage of 273 volts.

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