What do kW, kWh, A, and Ah mean? Today we discuss each of the terms. These are some units in electrical engineering, and they are related to the electric vehicles also. kW vs kWh, A vs Ah are also will be explained below.
Never get confused with these terms anymore!
Have you ever come across a lot of terms related to electric vehicles? We have a list of electric vehicle-related terms and brief explanations here in this Electric Vehicle Glossary: The complete list of electric vehicle-related terms
kW vs kWh (kiloWatt and kiloWatt-hour)
First of all, let’s see what kiloWatt (kW) and kiloWhatt-hour (kWh) are. Watt is the unit of power and Wh is the unit of energy consumption.
What is kW?
Watt is the SI unit of power which is equal to 1 Jule per second. It’s equivalent to the rate of energy consumption in an electric circuit where the potential difference is 1 Volt and Current is 1 A.
The unit of power is Watt named after James Watt. When we write the unit, the letter W should be in the capital.
1 kiloWatt (kW) is equal to 1000W.
What is kWh?
kWh is the unit of energy. Equipment of 1kW rating consumes 1kWh energy if it operates for 1 hour. If electrical equipment of 1W operates for 1 hour, it consumes 1Wh.
So, 1Wh is equal to 3600 Jouls.
1 W = 1 J/s
1 Wh = 1 J/s X 1 hour
1 Wh = 1 J/s X (60 X 60) s
1 Wh = 3600 J
If 100W equipment operates for 10 hour then it consumes 1kWh.
In the case of Electric Vehicles, how this kWh is important?
The battery rating of Electric Vehicles is mentioned in kWh (Ah also). A battery of 1 kWh capacity can supply 1000W load for 1 hour.
- 1kWh battery can supply 100W load for 10 hour
- 1kWh battery can supply 500W load for 2 hour
So in an electric vehicle, if a 250W motor continuously operates, it consumes 1kWh in 4 hours.
kW vs kWh
What is the differene between 1 kW and 1 kWh?
1 kW is the power rating of and equipment and 1kWh is the energy consumed by the equipment of 1kW power rating if it operates for 1 hour.
As we explained above, if an electric vehicle has a motor of 1kW rating and it works continuously for 1 hour, then the energy consumption would be 1kWh. So a battery of capacity 1kWh can supply a motor of 1kW for one hour.
Or it can drive a motor of 250 W for 4 hours.
Do you understand the difference of kW and kWh?
A vs Ah (Ampere vs Ampere-hour)
What is A?
An Ampere is the unit of electric current in an electrical circuit. It’s the measure of the rate of electron flow in an electrical conductor.
One Ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) moving past a specific point in one second.
The Ampere is named after Andre Marie Ampere.
What is Ah?
Ampere hour is a unit of electric charge that has a dimension of electric current multiplied by time. One Ampere hour is equal to 3600 coulombs.
1 Ah = 1 Coulomb/s X hour
1 Ah = 1 Coulomb/s X (60 X 60) s
1 Ah = 3600 Coulomb
Ampere-hour shows how long an electric battery can supply a specific electric current. For example, 1 Ah battery can supply one Ampere current for 1 hour.
It can deliver 2 Ampere current for half an hour. Or 0.5 A current for 2 hours.
The voltage rating of a battery has to be mentioned along with Ah capacity of a battery.
- 24V, 2 Ah battery – The energy in the battery is equal to 48Wh
- 48V, 2 Ah battery – The energy in the battery is equal to 96 Wh
The Watt hour rating of the battery depends on the voltage of the battery also.
Have you tried the tool: Ah to kWh Calculator?
Conclusion
We have discussed a few terms (kW and kWh, A and Ah) related to an electric vehicle in detail. More terms related to electric vehicles are listed and explained in Electric vehicle glossary.
We explained kW vs kWh, A vs Ah and how they are important in an electric vehicle.
Key points
- kW is the unit of power and kWh is represents energy consumption
- kWh represents the capacity of a battery in an Electric Vehicle
- A is the unit of electric current
- Ah is represents current flow for an hour
