For the (future) driver of an
Electric Auto (EA) it is very important to know how much "fuel", i.e. how much electric energy it consumes and
how the consumption is measured.
Electric Energy for Electric Autos is usually not measured in liters or gallons, but in
kilo-Watt-hours (kWh), a measurement unit you can find on your electricity bill, for example.
A kilo-Watt-hour (kWh) is the product of kilo-Watts (kW) and hours (h) :
1 kWh = 1 kW x 1 h
1 kilo-Watt (kW) = 1000 Watts (W)
That means : If you have a vacuum cleaner which consumes 1 kW (= 1000 Watts) and you let it run for 1 hour (h), then it has consumed 1 kilo-Watt-hour (kWh) of electric energy.
Within a
battery the electric energy is stored by
charge carriers (electrons, ions, ...).
You could also say : Before you want to ride your Electric Auto you must "feed" the charge carriers in the batteries with electric energy, i.e. you must
charge the batteries.
The number of charge carriers within a battery for Electric Autos is usually called
capacity and measured in
Ampère-hours (Ah).
The amount of electric energy that can be carried by a certain number of charge carriers within a battery is called
voltage, measured in
Volts (V) and depends on the materials the battery is composed of (e.g. lead, nickel, lithium, ...). Voltage could also be described as
"energylevel of the charge carriers".
If the voltage in a battery is on a level of 1 Volt (V), then 0,001 kWh of electric energy are carried by 1 Ah of charge carriers :
1 V = 0,001 kWh/Ah
The battery system of the
Toyota RAV4 EV has a nominal voltage of
288 V (= 0,288 kWh/Ah) and a capacity of
100 Ah.
That means that the amount of electric energy, that can be stored in this battery system, is ca. 28,8 kWh, because
0,288 kWh/Ah x 100 Ah = 28,8 kWh.
Other common units for energy are
kilo-Calories (kcal) or
kilo-Joule (kJ), that you can find on food packages for example.
1 kcal = 4,18 kJ = 0,0011611 kWh
100 grams (ca. 0,2 pounds)
Basmati rice contain
ca. 350 kcal of
food energy, which is equivalent to
ca. 0,4 kWh of
electric energy.
1 liter (ca. 0,26 US.liq. gallons = ca. 0,22 Imp. gallons) of
gasoline or diesel contains
ca. 35.000 kJ of
chemical energy, which is equivalent to
ca. 10 kWh of
electric energy.
So
28,8 kWh are equivalent to ca. 2,88 liters (ca. 0.76 US. liq. gallons = ca. 0,64 Imp. gallons) of gasoline or diesel, a
Toyota RAV4 EV can drive
ca. 160 km (100 miles) on it.