Explained
How a electric car anatomy works.
How an electric car works
An electric car swaps the engine, fuel tank and multi-speed gearbox for a battery, one or more electric motors and the power electronics that join them. Most modern EVs are built on a skateboard layout: a flat battery pack fills the floor between the axles, with a compact drive unit at one or both ends. The body and cabin sit on top. This model is a generic car, not any particular brand.
Putting the heaviest part of the car low in the floor gives it a low centre of gravity, which helps handling. It also frees up space: with no engine in front there's often a storage compartment where it would have been, and the cabin floor can be flat.
Battery, cells and the BMS
The battery pack is made from thousands of lithium-ion cells, grouped into modules and wired in series and parallel to reach a high voltage, often around 400 or 800 volts. Some cars use cylindrical cells, named for their size; an 18650 cell is 18 millimetres across and 65 millimetres long. Others use flat pouch or prismatic cells.
The battery management system is the pack's guardian. It measures the voltage and temperature of every group of cells, balances their charge so none is overcharged, and limits power when the pack is too hot or too cold. A liquid cooling loop runs under the modules to keep them in the right temperature range, warming them in winter and cooling them during fast charging.
Motors, inverters and regenerative braking
The battery supplies direct current, but most EV motors run on alternating current. The inverter switches the DC on and off thousands of times a second to make AC at whatever frequency the motor needs, which sets its speed and torque. Electric motors pull strongly from a standstill and spin happily to very high speeds, so most EVs use a single fixed reduction gear instead of a gearbox.
Lift off the accelerator and the inverter runs the motor as a generator. That slows the car and sends energy back into the battery, which is called regenerative braking. The friction brakes are still there for hard stops. Explode the model to lift the body off the skateboard, or open Play to remove one system at a time.
Parts glossary
- Body shell
- The body sits on top of the skateboard-style chassis. Here it is shown see-through so you can see what's underneath.
- Interior
- With no engine or transmission tunnel, the floor can be flat and the cabin roomier for the car's size.
- Battery pack
- The pack fills the floor between the axles. Its weight sits low, which helps the car corner and resists rollover. Fun fact: Cylindrical cell sizes are named by their dimensions: an 18650 cell is 18 mm across and 65 mm long.
- Battery modules
- Thousands of cells are grouped into modules, joined by busbars into a high-voltage string.
- Battery management system
- The BMS watches the voltage and temperature of every group of cells and keeps them balanced and within safe limits.
- Drive units
- Each drive unit is an electric motor with a single-speed reduction gear. With one at each axle the car has all-wheel drive. Fun fact: Electric motors deliver strong torque from a standstill, so most EVs need only one gear ratio.
- Inverters
- The inverter turns the battery's direct current into the alternating current the motor needs, and controls the motor's speed and torque.
- High-voltage cables
- Orange cables carry high-voltage power between the pack, the inverters and the charger. The colour is a safety convention.
- Charge port and onboard charger
- The charge port on the rear wing takes the plug. The onboard charger converts AC from a home charger into DC for the pack. DC fast chargers bypass it and feed the battery directly.
- Cooling loop
- Coolant loops and a radiator keep the battery, motors and electronics at the temperature they work best at.
- Heat pump
- A heat pump moves heat instead of making it, warming the cabin and battery in winter using far less energy than a resistive heater. Fun fact: A heat pump can deliver two to three units of heat for every unit of electricity it uses.
- Crash structure
- Bumper beams and crumple rails at each end, plus strong side sills, absorb crash energy and protect the battery pack.
- 12-volt (LV) battery
- A small low-voltage battery runs the lights, screens and computers and wakes the high-voltage system up.
- Suspension
- Springs and dampers at each corner, much like any other car.
- Brakes
- Friction brakes are still fitted, but much of the slowing is done by the motors running as generators. Fun fact: Regenerative braking turns the motor into a generator, sending energy back to the battery as the car slows.
- Wheels
- Large wheels and low-rolling-resistance tyres help efficiency.
Fan-made educational model, not affiliated with or endorsed by Tesla, Inc. or any brand mentioned.
