How to Jump Start a Car Safely (Step-by-Step) 🔋

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Words: AutoTrader NZ
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Published 23 April 2026

A flat battery can happen to anyone – especially during colder months or if your car hasn’t been driven in a while. Knowing how to jump start your car safely is a simple skill that can save you time and stress.

Here’s how to do it properly.

1. What You’ll Need

  • Jumper leads
  • Another vehicle with a working battery
  • A safe place away from traffic

👉🏼 Top tip: Keep jumper leads in your boot – you never know when you’ll need them.

2. Safety First

Before you start:

  • Turn both cars off
  • Put them in park or neutral
  • Apply the handbrakes
  • Keep leads away from moving parts

Never attempt to jump start a damaged or leaking battery.

3. Connect the Jumper Leads in the Correct Order

Step 1

Connect the red clamp to the + (positive) terminal on the flat battery.

Step 2

Connect the other red clamp to the + terminal on the working battery.

Step 3

Connect the black clamp to the – (negative) terminal on the working battery.

Step 4

Connect the final black clamp to an unpainted metal surface (like the engine block) on the car with the flat battery – not directly to the battery.

👉🏼 This helps reduce the risk of sparks.

4. Start the Cars

  • Start the working car first
  • Let it run for a minute or two
  • Then start the car with the flat battery

Once it starts, let both cars run briefly.

5. Remove the Leads (Reverse Order)

  • Remove black clamp from metal
  • Remove black clamp from working battery
  • Remove red clamp from working battery
  • Remove red clamp from flat battery

6. After the Jump Start

Drive the car for at least 20–30 minutes to allow the battery to recharge.

If your battery keeps going flat, it may need replacing.

7. Alternative: Portable Jump Starters

Instead of using another vehicle, you can use a portable jump starter kit.

These are compact, battery-powered devices that allow you to jump start your car without needing another car. They’re especially useful if you’re travelling alone or parked somewhere remote.

Bottom Line

Jump starting your car is simple – but the order matters. Following the correct steps helps avoid damage and keeps you safe.

👉🏼 A little preparation can save you a lot of hassle when a flat battery strikes.