How to Jump Start Your Car
Learn how to safely jump start a dead battery with jump leads or a jump starter pack. Essential skill for all UK drivers.
⚠️ Critical Safety Warning
- • NEVER connect cables in the wrong order - can cause sparks, fire, or explosion
- • Both cars must have 12V batteries (check before starting)
- • Never let the jump lead clamps touch each other
- • Remove metal jewelry and keep away from moving parts
- • If battery is cracked, leaking, or frozen - DO NOT jump start, call for help
What You'll Need
- Jump leads (heavy-duty cables with clamps) - £15-30
- A donor car with a good battery (or a portable jump starter - £40-100)
- Owner's manual - some cars have specific jump start points
Step-by-Step Instructions
1. Position the Donor Car
Park the donor car close enough so the jump leads can reach both batteries, but make sure the cars are NOT touching. Put both cars in Park (automatic) or neutral (manual) with handbrakes on.
Tip: Check your handbook - some modern cars have specific jump start terminals, not direct battery access.
2. Turn Everything Off
Turn off both car engines and all electrical items (lights, radio, heater, etc.) in both cars.
3. Identify Battery Terminals
Locate the batteries in both cars. Identify the positive (+) and negative (-) terminals:
- Positive (+): Usually has a red cover or red cable
- Negative (-): Usually has a black cover or black cable
4. Connect Red Cable to Dead Battery Positive (+)
Take the RED jump lead. Attach one red clamp to the positive (+) terminal of the DEAD battery.
⚠️ Make sure the clamp is secure and making good contact with the terminal.
5. Connect Red Cable to Donor Battery Positive (+)
Attach the other end of the RED jump lead to the positive (+) terminal of the DONOR (working) battery.
6. Connect Black Cable to Donor Battery Negative (-)
Take the BLACK jump lead. Attach one black clamp to the negative (-) terminal of the DONOR (working) battery.
7. Connect Black Cable to Earth Point
Attach the other end of the BLACK jump lead to an unpainted metal surface on the dead car's engine block - NOT the battery negative terminal.
Good earth points: Engine block, metal bracket, or chassis. Check handbook for recommended point.
⚠️ DO NOT connect to the negative terminal of the dead battery - this can cause sparks near the battery.
8. Start the Donor Car
Start the donor car's engine and let it run for 2-3 minutes. This charges the dead battery slightly.
Optional: Rev the donor car gently to about 2000 RPM to help charge faster.
9. Try to Start the Dead Car
With the donor car still running, try to start the dead car. It should start within a few seconds.
If it doesn't start after 3-5 seconds, stop and wait a minute before trying again.
10. Remove Cables in REVERSE Order
Once the dead car is running, remove the jump leads in the EXACT REVERSE order you connected them:
- Remove BLACK clamp from dead car's earth point
- Remove BLACK clamp from donor battery negative (-)
- Remove RED clamp from donor battery positive (+)
- Remove RED clamp from dead battery positive (+)
⚠️ Don't let the clamps touch each other or the car body while removing them.
11. Keep the Engine Running
Keep the jumped car running for at least 20-30 minutes to recharge the battery. Don't turn it off or you might need another jump start!
Quick Reference: Connection Order
| Step | Cable | Connect To |
|---|---|---|
| 1 | RED | Dead battery POSITIVE (+) |
| 2 | RED | Donor battery POSITIVE (+) |
| 3 | BLACK | Donor battery NEGATIVE (-) |
| 4 | BLACK | Dead car EARTH point (NOT battery negative) |
Remove in REVERSE order!
⚠️ After Jump Starting
- 1. Drive for 20-30 minutes: This recharges the battery. Don't turn off the engine
- 2. If it won't start next time: Your battery may be dead and needs replacing
- 3. Get battery tested: Visit a garage to test the battery and charging system
- 4. Check alternator: If battery keeps dying, the alternator may not be charging properly
Common Reasons for Dead Battery
- •Lights left on - Headlights or interior lights draining battery overnight
- •Old battery - Car batteries last 4-5 years on average
- •Short journeys - Battery doesn't have time to fully recharge
- •Faulty alternator - Not charging the battery while driving
- •Extreme cold - Cold weather reduces battery performance
- •Car not used regularly - Battery drains over time when not used
Track Your Battery Maintenance
Log battery replacements and all car maintenance in AutoChain. Keep a complete digital service history and get reminders.
Jump Starting a Car: Common Questions
How long should I run the engine after a jump start?
After a successful jump start, drive the vehicle for at least 30 minutes to allow the alternator to recharge the battery. Avoid switching off the engine for short-stop errands during this time. Ideally, take the car for a longer drive on an A-road or motorway where the engine can run at higher revs and the alternator produces maximum charge. If the battery is old or has deep-discharged repeatedly, driving may not be enough to fully restore it — consider using a dedicated battery charger overnight for a complete recharge.
Why does my car keep going flat and needing jump starts?
Repeatedly needing jump starts usually means the battery needs replacing or there is an underlying electrical fault. Common causes include: a battery that has reached the end of its service life (typically 3–5 years); a faulty alternator that is not charging the battery while driving; a parasitic drain from an electrical component that stays active when the car is switched off; or a battery that has been deeply discharged too many times and has permanently lost capacity. A garage can test the battery and charging system in minutes to identify the cause.
Can I jump start a modern car with stop-start technology?
Jump starting a modern car with stop-start, AGM (Absorbent Glass Mat) or EFB (Enhanced Flooded Battery) technology should be done carefully. These vehicles use more sophisticated battery management systems that can be sensitive to voltage spikes from conventional jump leads. Many manufacturers recommend using a CTEK or similar smart battery charger rather than jump leads where possible. If you must use jump leads, follow the vehicle manufacturer's specific instructions in the handbook. Connecting leads incorrectly to vehicles with sensitive electronics can damage the ECU or other modules.
What is the correct order to connect jump leads?
Connect jump leads in this order: first, red (positive) to the flat battery positive terminal; second, red (positive) to the good battery positive terminal; third, black (negative) to the good battery negative terminal; fourth, black (negative) to an unpainted metal earth point on the engine block of the flat car — not the flat battery negative terminal. This order reduces the risk of sparks near the battery. Disconnect in reverse order after starting. Never connect the cables to a frozen battery as this can cause it to crack or explode.
Can I use a jump start pack instead of another vehicle?
Yes — portable lithium-ion jump start packs (also called jump starters or booster packs) are an excellent alternative to relying on another vehicle. Modern compact units can start a petrol engine up to 3.0 litres or a diesel up to 2.0 litres from a device small enough to fit in a glovebox. They are particularly useful if you drive alone or park where other cars are not easily accessible. Ensure the pack is fully charged before winter, as lithium batteries lose capacity in cold temperatures. Most also double as USB power banks for charging phones.
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