Electric Vehicle Frequently Asked Questions

EV TERMINOLOGY

What does the term ICE mean?

ICE is an abbreviation for Internal Combustion Engine; generally meaning either a conventional gasoline or diesel fueled engine. On the EV Discussion List ICE is frequently used as a general reference to conventional automobiles.

What is an electric vehicle (EV)?

An EV (electric vehicle) is a motor vehicle propelled exclusively by electricity. While generally used in reference to electric powered automobiles, a great many non-road going vehicles including forklifts, burden carriers, and golf carts are electric powered. As an extreme example even the Lunar Rover used by the astronauts on the moon would be considered an EV.

What is a hybrid (HEV)?

A hybrid or HEV (hybrid electric vehicle) is a motor vehicle propelled by two sources of power, one of which is electricity. Most HEVs are gas/electric hybrids such as the Toyota Prius. Generally, in order to be considered a hybrid, a vehicle must either be able to move using either power source, or supplement one power source with another. For example a Toyota Prius is a hybrid because it uses two drive systems, one electric powered and one gasoline powered, and can operate on either one. In comparison a diesel/electric locomotive, while it does combine both electric and diesel elements in its drive system, would not be considered a hybrid, because it cannot move without using the diesel engine to supply power. In a diesel/electric locomotive, the electric drive component actually represents a transmission rather than a power source.

What is an neighborhood electric vehicle (NEV)?

An NEV (neighborhood electric vehicle) is a classification for a small electric vehicle designed for low speed operation in restricted areas. By law they are not permitted to exceed 25 miles per hour, or be operated on roads with higher speed limits than 35 MPH. Because of their limited use they are not required to meet all conventional Department of Transportation safety standards. They are not yet legal in many states.

What is a flooded battery?

The term 'Flooded battery' generally refers to a conventional lead-acid battery with a liquid electrolyte inside. These batteries are equipped with removable caps to replenish the water lost during charging. Some EVs, which use these batteries, are equipped with automated watering systems. In addition to lead-acid based batteries, some nickel-cadmium and nickel-iron batteries are made in flooded versions. Flooded batteries tend to be less expensive and more forgiving of overcharging that sealed batteries, but they can require addition cleaning and servicing.

What is a sealed battery?

A sealed battery is one that is not designed to vent to the atmosphere, under routine conditions. A rechargeable flashlight battery is an example of a sealed battery. Sealed batteries do not require the addition of water or other servicing. Sealed batteries tend to be more expensive than flooded batteries, and require more sophisticated charging systems. They are also typically capable of delivering higher currents without damage.

What does AGM mean?

AGM is an abbreviation for Absorbed Glass Mat. This is a method of construction used in some sealed batteries. The mat itself is a sponge-like material that acts as a medium to absorb and retain the liquid electrolyte of the battery. Most AGM batteries can be installed in almost any position.

What does VRLA mean?

VRLA stands for Valve Regulated Lead Acid. VRLA batteries are sealed batteries equipped with pressure safety valves. Under normal conditions these valves stay closed, and prevent any gas escaping or loss of electrolyte. However, if charging currents become too high, or the battery overheats, the gas pressure produced inside the battery may open these valves, causing gases and electrolyte to vent. Once these have escaped there is normally no means to replace them, so the battery will permanently lose some capacity.

What is regen and why is it desirable?

Regen is short for regenerative braking. This basically is a system by which the energy of a decelerating EV is harnessed, either by using the drive motor as a generator, or by driving a separate generator. The electricity created by this process is fed back into the drive battery pack, restoring some of the charge. Regenerative braking seldom has a significant effect on overall range, but it does improve drivability, and reduces brake wear. Most AC drive electric vehicles include this feature, but it is only rarely found on DC drive EVs.