Currently most electric vehicles use either nickel metal hydride (NiMH) or lithium-ion (Li-ion) batteries providing a DC voltage as much as 500v, along with a power rating of everything from 18 to 50 kilowatt-hours. This is why you will need a charging station or a special kit to rapid-charge an EV battery. A typical household electrical supply simply isn’t capable of providing the amount of power required to carry out a quick-charge.
Li-ion batteries are actually preferred because, configured correctly, they can weigh less than half of the things a similar capacity NiMH battery pack weighs. Tesla’s current generation battery pack crams a great deal power into such a small footprint which they currently have the greatest energy density in the industry, then one pack could run a small house for a couple of days on one charge.
Tesla’s battery packs are unique in that they normally use thousands of 18650 form factor cells that are 18mm in diameter by 65mm long. The cells appear like AA batteries if you dismantled the battery pack. Tesla report that this form factor increases life of the battery and is more efficient for heat transfer.
The Chevy Volt, by comparison, utilizes a more traditional system of interleaved vertical plates packed together into modules, several of which can be stacked to form the entire battery pack – a T-shaped unit that sits behind the rear seats and protrudes down the centre of the car where a traditional transmission tunnel would be.