Why jumpstarting your car is not a good idea

Mechanic checking a car battery
  • There are computers in modern cars that control the major and minor functions – jumpstarting your car can damage them
  • There’s a bigger risk of doing damage when you jumpstart a modern car compared with a pre-2000 model
  • It is safer to leave the revival of a flat battery to an expert, such as an NRMA technician

There are a lot more complex electronic systems in today’s cars than those of a decade, or even five years ago, which is why jumpstarting your car is never a good idea.

Great gains in luxury and convenience have come with the extra electronics, which have given rise to features such as satellite navigation and Bluetooth connectivity, and life-saving safety equipment such as airbags and electronic stability control.

But one of the downsides becomes clear when you have a flat battery – in a modern car, there’s a greater risk of expensive damage to the on-board electronics than in an older model, as NRMA technical trainer Darrin Tucker explains.

Why you should never attempt to jumpstart your car

“The big change from then to now is computers and it’s not as if a modern car has just one – a Mercedes-Benz S-Class from a few years ago has 64 ECUs (Electronic Control Units),” he said. “Hooking up jumper leads can zap these computers.

“Jaguar warned us that you could damage the whole wiring harness if you try to jumpstart one of their cars, and that warning is probably applicable to most vehicles built in the past five years.

“A five-year-old Audi was recently taken to an NRMA approved repairer with an electrical system so badly damaged by an attempted jumpstart that, in the end, it was actually cheaper to write the car off rather than repairing the damage.”

“Well-meaning car owners can do massive damage very easily,” Darrin says.

Special NRMA patrol vehicles are equipped with surge protectors to safely revive a flat battery in a modern car.

While some jumper leads and booster batteries you can buy at a spare parts store come with a surge protector, it must be oriented the right way and connected in the correct sequence, and even then there is no guarantee you won’t damage your car.

It’s best to leave the revival of your car’s flat battery to an expert. If you need help book NRMA roadside assistance or call 13 11 11 to request a patrol.

Need assistance?

The NRMA will give you the right advice or replace your car battery if required