Jump-starting a dead car battery may seem simple. However, incorrect use of jumper cables can damage your vehicle and cost you a lot of money. Here’s a practical guide to safely recharge your car battery, avoid costly mistakes, and know when to call a professional.
If your car battery is weak, use a car battery charger instead. If it’s fully dead, the safest thing to do is call Roadside Assistance.
Of course, you can also boost your car yourself. Follow our tips while making sure they match the procedure recommended in your vehicle’s owner’s manual.
What to check before jump-starting a car battery
Make sure the two vehicles don’t touch.
Check that the dead battery isn’t frozen or swollen. Avoid jump-starting if the casing is wavy or bulging to prevent premature wear or even an explosion.
Keep flames and sparks away (no smoking!): batteries release hydrogen gas, which is highly explosive.
Wear gloves and safety glasses, and remove jewellery and bracelets. Battery leaks are rare, but the electrolyte inside can cause severe burns. If it comes into contact with your skin, rinse thoroughly with water and seek medical attention.
Turn off all electrical accessories (heating, lights, AC) and apply the parking brake.
Manual transmission: put the gearshift in Neutral.Automatic transmission: select Park (P).
If in doubt, call Battery Service if you’re a member. It’s the safest way to recharge a dead car battery without damaging the terminals or electronic components.
How to jumpstart a car battery step by step
This method also applies if you’re using a portable car battery booster instead of another vehicle.
1. Open the hoods of both vehicles and connect the red clamp to the positive (+) terminal of the dead battery.
2. Connect the other red clamp to the positive (+) terminal of the good battery.
3. Connect the black clamp to the negative (–) terminal of the good battery.
4. Connect the other black clamp to te engine block of the disabled vehicle.
Pro tip
“You can also connect the black clamp to a metal component of the engine, such as the alternator bracket. Avoid the negative terminal of the dead battery and body panels. Keep the connection at least 30cm from the battery.”
6. Try starting the car with the dead battery according to your owner’s manual. Don’t crank the starter for more than 15 seconds to avoid damaging it.
7. Leave the cables connected for 5 minutes after the car starts to reduce the risk of a power surge. Run the heater and defroster for a few minutes to stabilize the charge.
8. Remove the cables in the reverse order of installation.
Your vehicle’s ECU (on-board computer) may need a ECU reset after a dead battery. Turn the key to ignition on for a few minutes, then start the engine and let it idle.
Some components—such as the clock, radio, power windows, sunroof, or steering—may require specific resets. Consult the owner’s manual or a mechanic if needed.
Warning: Not following instructions when jump-starting with a booster battery can cause serious injury. CAA-Quebec cannot be held responsible for any personal injury or property damage resulting from the use of this method.
Common mistakes to avoid when jump-starting a car battery
Jump-starting isn’t complicated, but it requires basic knowledge. You must connect the cables correctly and follow the right sequence. For example, improper handling can fry the on-board computer and cost at least $1000 to replace. Here are 3 mistakes to avoid—and their consequences:
Disconnecting cables too quickly = Power surge
Connecting clamps to the wrong terminals = Fried computer
Connecting directly to the negative terminal of the dead battery = Explosion risk
Damage after a jump-start: What does your auto insurance cover?
The jump-start went wrong and your vehicle is damaged? Who pays for the repairs—you or your insurer? It depends on the situation.
Professional jump-start: Covered by their liability insurance. CAA-Quebec and its partners carry this coverage. If a problem occurs, you’ll receive compensation.
You: Your auto insurance may reimburse you if you have “Comprehensive” auto insurance coverage (also known as Section B3 or fire, theft and vandalism coverage).
Friend/Good Samaritan: Your auto insurance (under the conditions above), and your friend’s liability insurance if the mistake was unintentional. A deductible always applies—usually between $50 and $500 depending on your policy.
Frequently asked questions (FAQ) – Jump-starting and car batteries
Q1: Can I jump-start my car battery myself? Yes, but only by following the guide, your owner’s manual instructions, and by using jumper cables correctly. A mistake can be very costly.
Q2: What are the risks of jump-starting? Improper handling can cause a power surge, damage electronic components, or trigger a battery explosion due to gas buildup.
Q3: How can I avoid these costly mistakes? Connect the cables in the correct order, don’t disconnect them too quickly, and avoid connecting to the negative terminal of the dead battery.
Q4: Who pays if my car is damaged during a jump-start? Professional: their insurance. You or your friend: your auto insurance (under certain conditions) or theirs. A deductible of $50 to $500 generally applies.
Q5: How long should the cables stay connected to safely recharge the battery? At least 5 minutes to fully recharge the battery and reduce the risk of a power surge.
Q6: What’s the difference between jump-starting and boosting a car battery? There’s no real difference. “Boosting” is a commonly used term in Quebec to describe recharging a vehicle’s battery. “Booster cables” or “boosting cables” refer to jumper cables.
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