Can You Jumpstart an Electric Car? UK Guide 2026
EV Charger Guidance • Page 15

Can You Jumpstart
an Electric Car?

Yes you can jumpstart an EV but only the 12V auxiliary battery, not the main traction battery. The 12V battery powers the car's computers and controls. Get that running and the EV can wake up and access its main battery. Here is the UK procedure.

Authored by: NAPIT Approved Engineers
Reviewed: April 2026
Coverage: Bedford, Milton Keynes, Northampton, Luton
Quick answer

Yes for the 12V auxiliary battery, no for the main traction battery. Modern EVs have a small 12V lead-acid battery that powers the car's computers, lights and accessories. If this 12V battery dies the car cannot wake up to access the main traction battery. A standard jumpstart from another car or jump pack restores the 12V system and the EV becomes operational again. The main traction battery cannot be jumpstarted and must be charged through the proper charger.

12Vlead acid

Battery That Jumpstarts

EVs have a small 12V lead-acid battery alongside the main traction battery. The 12V is what jumpstart procedures actually charge.

20%

Of EV Breakdowns

Around 20 percent of UK EV breakdowns trace to the 12V auxiliary battery failing. The single most common EV roadside issue.

5mins

Typical Jumpstart Time

A successful EV jumpstart from another vehicle or jump pack typically takes 5 minutes from start to engine ready (or rather, ready to drive).

4-6yrs

12V Battery Life

The 12V auxiliary battery lasts 4 to 6 years on average. Less than the main traction battery and the most common service item.

In this guide

What this page covers

01What 12V battery jumpstart looks like 02Why traction battery cannot be jumpstarted 03Step-by-step jumpstart procedure 04How to avoid 12V failures

How to jumpstart an electric car safely

The first thing to understand is that EVs have two batteries. The main traction battery (the big one in the floor) provides power to the motor. The 12V auxiliary battery (a small standard lead-acid like a petrol car has) powers the computers, lights, infotainment and the contactors that connect the main battery to the rest of the car.

If the 12V battery dies, the EV cannot wake up. The contactors stay open. The car has no power to its screens, no responsive controls and cannot draw from the main traction battery even if it is fully charged. The car appears completely dead from the driver's perspective.

Why the 12V battery fails

The 12V battery powers the EV's computers continuously, including the security system, remote unlock and the cellular modem that talks to the manufacturer's servers. Even when 'parked', the car draws a small amount of 12V current. If you leave the EV unused for several weeks, the 12V battery can fully discharge. Cold UK winters accelerate the drain.

Other causes include accidentally leaving lights or accessories on overnight (some EVs are good at warning, others are not), age-related battery degradation (4 to 6 years is typical service life) and connector corrosion.

Why you cannot jumpstart the main battery

The main traction battery operates at 350V to 800V depending on the EV. You cannot jumpstart something at this voltage from another car or any portable jump pack. If the main traction battery is fully drained, the EV must be plugged into a charger to recover. Modern EVs have software that prevents the main battery from discharging below safe minimums but if it does happen (rare), only proper charging restores it.

Jumpstart procedure

The 12V jumpstart procedure for an EV is essentially the same as for a petrol car. Connect a donor vehicle or jump pack positive to the EV's 12V positive (often a remote terminal under a flap, not directly on the small battery). Connect negative to a chassis earth point. Power the donor vehicle on, wait a few minutes for charge to transfer and try to power up the EV. Once the EV is alive, disconnect in reverse order.

Authoritative context

UK roadside recovery providers including the AA, RAC and Green Flag publish specific procedures for EV jumpstarts and have trained their fleet recovery operatives accordingly. EV manufacturer handbooks include 12V jumpstart procedures with vehicle-specific connection points highlighted. The 12V auxiliary battery system is governed by general automotive electrical safety standards under ECE regulations. Modern EVs include sleep-mode optimisations to extend 12V battery life when the vehicle is parked for extended periods.

EV battery system overview

Main traction battery
The large lithium-ion pack powering the motor. 350 to 800V. Cannot be jumpstarted. Requires charging through proper charger.
350-800V
12V auxiliary battery
Small lead-acid battery powering computers, lights and accessories. Standard jumpstart works.
12V
DC-DC converter
Module that charges the 12V battery from the main traction battery while driving. Failure causes 12V depletion.
Auto

EV jumpstart procedure

1

Locate the 12V terminals

Most EVs have remote 12V jumpstart terminals (often under the bonnet or in the boot). Check the vehicle handbook for exact location.

2

Connect positive to positive

Donor vehicle or jump pack positive to EV's 12V positive jumpstart terminal. Use proper jump leads rated for the current.

3

Connect negative to chassis earth

Connect negative to a chassis earthing point on the EV (typically a bare metal bolt or designated earth tag), not directly to the 12V negative.

4

Wait, then power on the EV

Allow 2 to 3 minutes for charge transfer. Press the EV's start button. The car should wake up and the dashboard come to life. Disconnect in reverse order.

Key facts UK EV drivers should know

12V dies most often

Around 20 percent of UK EV breakdowns are 12V battery related. The single most common cause of an EV that will not start.

Standard jumpstart works

Any donor car or jump pack rated for 12V automotive use will successfully jumpstart an EV's auxiliary battery system.

Main battery cannot be jumped

If the main traction battery is fully drained, only proper charging restores it. No jumpstart from any source can revive it directly.

Replace 12V every 4 to 6 years

Replacing the 12V auxiliary battery proactively before failure prevents most EV roadside issues. Cheap and quick service item.

Petrol car jumpstart

  • 12V battery powers starter motor
  • Engine cranks once 12V restored
  • Direct connection to 12V battery
  • 5 to 10 minute typical procedure
  • Once running, alternator recharges 12V
  • Similar across all petrol cars

EV jumpstart

  • 12V battery wakes up computers
  • Car powers up once 12V restored
  • Often remote 12V terminal not directly on battery
  • 5 minute typical procedure
  • DC-DC converter recharges 12V from main battery while driving
  • Procedure varies slightly by manufacturer

12V battery management is one practical EV ownership topic. The wider EV Charger Guidance hub covers home charger install, running cost, the buying decision and the dozens of practical questions UK drivers ask about EV ownership.

If you are dealing with EV recovery scenarios, our guide on can you push an electric car covers the moving-a-dead-EV question. The towing version is in can you tow an electric car. For parked battery drain see do electric cars lose charge when parked.

Recovery

Can you push an electric car

 Recovery

Can you tow an electric car

 Battery

Do electric cars lose charge when parked
Frequently asked

Common questions

Can I jumpstart my EV from another EV?
Yes provided the donor EV has a 12V jumpstart terminal you can access. The donor car powers the recipient through the 12V system. Some EVs (Tesla, Hyundai Ioniq 5) have specific procedures for donor mode. Many EVs prefer being woken up by a jump pack or petrol car donor rather than another EV. Check both vehicles' handbooks.
What if my main traction battery is completely flat?
If the main traction battery is fully discharged (rare but possible if the car has been parked for many months), it must be charged through a proper EV charger. Some manufacturers require a dealer visit to wake the car up first. Plug the car into a slow charger and leave it for several hours. The car's onboard charger will recover the main battery from a deep discharge state.
Will jumpstarting damage my EV's electronics?
Not if done correctly. Use proper jump leads rated for the current. Connect to the designated 12V jumpstart terminals identified in the vehicle handbook (often remote terminals, not directly on the small battery). Connect positive first, then negative to chassis earth. Reverse the order to disconnect. Following the manufacturer procedure carries no significant risk to the EV's electronics.
How can I prevent my 12V battery from dying?
Drive the EV at least once every 2 to 3 weeks if possible. Plug into the main charger occasionally even if you don't need to charge much. Replace the 12V auxiliary battery proactively every 4 to 6 years before age-related failure. Consider a smart trickle charger if the car is parked for very long periods. Some EVs have a 'maintenance mode' that periodically tops up the 12V battery from the main pack.
Why do EVs even have a 12V battery?
Two main reasons. First, almost all automotive electronics (lights, infotainment, ECUs, security systems, remote modems) are designed for 12V because the rest of the automotive industry runs on 12V. Using a 12V auxiliary system is far cheaper than redesigning everything for 350V to 800V operation. Second, the 12V system can power critical safety systems even when the high-voltage main battery is disconnected for service or in an accident.

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