Will a car run without a battery


Pro Tuner
Staff member
2002 Clio 172
If you took the battery out of a car after starting it would it still happily run?

I've had a flat/dead battery before and the car seemed to work ok after it had been jumped. But I need your help to settle a debate!

I thought the alternator provides enough current to bypass the need for a battery and that the battery is just used to start the car.

A friend says you need the battery to act as a buffer but I'm pretty sure the alternator kicks out enough current and this fluctuates depending on engine demand.

What are your thoughts?

HDi fun

TC ModFather
Buckinghamshire UK
Passat 2.0 TDi
The battery is simply a very large electrolytic capacitor. The alternator does supply sufficient current but the battery acts as a smoothing capacitor which protects delicate DC systems from voltage ripple. In some cases it also acts as a voltage reference but I think this is less relevant now than it was say 30 years ago.

Similar threads