Battery capacity is measured in kilowatt-hours or kWh. This is very different from the way gasoline is measured in gallons, as it has nothing to do with weight or volume, but how much actual energy is available. Typically, kWh is used as a measure of work. You usually see this on your utility bill, where it indicates how much power you used.
For example, a 300-watt space heater would need to run for just over three hours to use 1 kWh, while a 60-watt lightbulb would need to run for over 16 hours. The average American household uses about 30 kWh a day.
The efficiency of electric cars is best measured as the number of kWh it takes to travel 100 miles, or kWh/100 miles. As with a gas car, more “fuel” doesn’t always mean more range; Efficiency also plays a major role.
It’s important to note that charging speed uses kilowatts, not kWh. A watt measures the rate at which energy flows; kWh is a way of measuring how much energy has flown.
Voltage: 400 Vs vs 800 V
Different electric car platforms are capable of handling different voltages. By increasing voltage, you can increase power (wattage) without increasing the amount of current (amperage). This means less heat, less cooling required, lighter weight components and greater efficiency. One of the most important advantages of EVs with 800-volt architecture is faster charging… assuming you can find a powerful enough charging station.
For the most part you’ll see 400-volt or 800-volt cars, although there are some outliers. The Lucid Air uses a suspiciously specific 924-volt architecture. Some vehicles, such as the Hummer EV, use 400 volts for driving and 800 volts for charging. Some have variable limits, such as the Porsche Taycan, which can temporarily charge up to 1,000 volts.
Ultimately, higher voltage systems offer weight savings and better performance but come with a higher price tag.
Batteries require direct current (DC) to charge, and they release stored energy in the form of direct current. But for Level 1 or Level 2 charging, the power that comes from your wall socket is alternating current (AC). Motors in electric cars run on alternating current (and recover energy in the form of alternating current) because alternating current allows them to deliver more torque and more consistent operation regardless of conditions.
Power inverters convert DC to AC and vice versa – although they do much more than that. This means they are a necessary component for both running your electric car and charging it at home. They convert the energy coming from the battery into a form that is usable by the electric motors, and they convert the energy recaptured by the motors, or the energy coming from a Level 1 or Level 2 charging station, to be used by the battery. convert appropriately.
Inverters are also capable of adjusting the frequency and amplitude of their outputs, which allows them to control the power and speed of an electric car’s motors. Alternating current comes in pulses, and when an inverter converts DC to AC it can control the frequency and amplitude (think, power) of the pulses. Increasing or decreasing the frequency of the pulses increases or decreases the speed of the motor, and increasing or decreasing the amplitude of the pulses increases or decreases the torque the motor produces.