Can you jump-start an electric car?

If your electric or hybrid car is refusing to start, you may well have a flat battery. But did you know that there are actually two batteries that could be causing the problem?

One is the main lithium-ion unit that powers the car itself, but there’s also a secondary 12-volt battery that powers the car’s ancillary features, such as the radio, headlights and wipers. This is the same type of battery that's also found in all combustion-powered cars.

Not only does this smaller 12-volt battery power the creature comforts, but it also ensures that the lithium-ion battery can be charged. If you've run out of electricity and need to recharge your car, it's likely that you'll have to jump-start this battery first.

Can you jump-start an electric car?

You may need to jump-start an electric car if its batteries have been completely drained, or if the 12-volt battery is worn and struggling to hold a charge. The lithium-ion batteries may not be able to be recharged unless the vehicle is jump-started via the 12-volt system, allowing the electronics that manage the charging process to operate first. 

The process of jump-starting an electric or plug-in hybrid vehicle is no different to any other car, but what might prove a bit more difficult is locating the 12-volt battery. The location of the 12-volt battery can differ between models, but your car’s handbook will tell you where it can be found.

Once you've located the battery, use a battery starter or another vehicle to boost it with appropriate jump leads, ensuring they’re firmly attached to the battery’s terminals in the correct order. If you're receiving a boost from another vehicle, this must be a petrol or diesel vehicle. An electric vehicle shouldn't be plugged in to charge when you jump-start it, either, as this may fry some of the on-board electronics and cause expensive damage.

The dead electric car must not be plugged into a charger when you attempt a jump-start. Only plug it in once you’ve completed the procedure, the car has fired into life, and the jump leads have been disconnected.

Can you jump-start a hybrid?

Like electric vehicles, plug-in hybrids can also be jump-started. The process should, in fact, be slightly easier because the battery will probably be located next to the engine – as it is in a conventional car. If it isn’t, consult your car’s handbook.

Can you use an electric car as a booster vehicle to jump-start other cars?

It's not recommended to use an electric or plug-in hybrid car to jump-start another vehicle. Doing so can put the on-board electronics at risk and potentially cause serious damage. Nissan advises owners of the Leaf not to use it as a booster vehicle, as its battery can't supply enough power to jump-start another car. Meanwhile, the handbook for BMW plug-in hybrids states they shouldn't be used for jump-starting. These are two specific examples, but it’s best to simply not use any electric or hybrid car to boost another vehicle.

If you can’t find a petrol or diesel car, or a battery booster, to restart your car, it’s time to make use of your breakdown cover – all the major providers will be able to resurrect an electric car unless the problems run much deeper. Should the problem be more severe, it’s recommended that your electric car is taken away on a flatbed truck, rather than by being towed behind another vehicle, as this can also cause damage.