How does a battery make an electric car's wheels turn?

An all-electric car carries energy in a large traction battery. The battery supplies direct current, or DC: electrical current with one overall direction. In a common electric drivetrain, an inverter uses electronic switches to turn this supply into controlled alternating current for the traction motor. Changing that electrical supply helps control the motor's turning force and speed.

Inside the motor, magnetic interactions create torque on a rotating part. Electrical energy is transferred into mechanical work as the shaft turns. The motor can rotate much faster than the car's wheels, so reduction gears connect the two. An 8:1 reduction means the motor makes eight turns for one turn of the driven axle. A motor turning at 4000 rpm would therefore correspond to an axle speed of 500 rpm in that example.

The gears trade rotation speed for a larger turning effect. They do not add energy. Neither do the other components pass along every joule as useful output. Electrical resistance, friction and other effects transfer some energy into heat. The illustration supplies example efficiencies for each stage: 1000 joules leaving the battery becomes 812.25 joules at the wheels, with the remaining 187.75 joules accounted as conversion losses.

Real cars have different motors, gearing and operating conditions, so those numbers are teaching inputs rather than a vehicle specification. Cooling systems manage heat, and controllers coordinate the parts. The main connection is the same: stored battery energy passes through controlled electrical conversion, becomes motor rotation and reaches the road through gears and wheels.