What You Need

  • Replacement battery (match the specifications on your old battery: group size, CCA cold cranking amps, voltage)
  • 10mm or 13mm spanner (most battery terminals use one of these)
  • Gloves and safety glasses — batteries contain sulphuric acid
  • Battery terminal cleaner or baking soda solution (optional)

Step-by-Step Battery Replacement

  1. 1

    Park on level ground and turn off the ignition

    Turn the car completely off. Remove the keys. Some modern cars require specific procedures before disconnecting the battery — check your owner’s manual for any pre-disconnect steps (some European cars have battery sensors that need registering).

  2. 2

    Disconnect negative terminal first

    Locate the battery (usually in the engine bay, occasionally in the boot). Identify the negative terminal (marked − and usually with a black cable). Loosen the clamp bolt and wiggle the terminal off the battery post. Move it well away from the battery and secure it so it cannot accidentally touch the post.

  3. 3

    Disconnect positive terminal second

    Loosen and remove the positive terminal (marked + with a red cable). Keep the positive cable away from metal surfaces — contact with the car body can cause a spark or short circuit.

  4. 4

    Remove the battery hold-down and lift out

    A clamp or bracket holds the battery in place. Remove it. Lift the battery out carefully — car batteries are heavy (15–25kg). Support from underneath, not by the terminals.

  5. 5

    Clean the terminal clamps and tray

    Inspect for corrosion (white or green powder on terminals). Clean with a wire brush or baking soda solution on a toothbrush. Rinse and dry. Clean terminals ensure good electrical contact.

  6. 6

    Install new battery — positive first, negative last

    Place the new battery in the tray ensuring correct orientation (positive post on the same side as positive cable). Secure the hold-down bracket. Connect the positive cable first, tighten firmly. Then connect the negative cable and tighten. The opposite order to removal.

  7. 7

    Start the car and reset electronics

    Start the car — it should start immediately. You will likely need to re-enter the radio code (if your radio has a code) and reset the clock, power window positions and other memory functions that clear when power is disconnected.

Disposing of the old batteryCar batteries contain lead and sulphuric acid — do not put in general waste. Most auto parts stores (Supercheap Auto, Repco, Battery World) accept old batteries for free recycling when you purchase a replacement. Council waste facilities also accept them.

Frequently Asked Questions

Check the label on your current battery — it shows the group size (e.g. NS70, 55D23L), voltage (12V for all standard cars), and CCA (cold cranking amps). Match these specifications or use a battery finder tool at auto parts stores (enter your car’s make, model and year). Going to a higher CCA than specified is generally fine and beneficial in cold climates — never go lower.
Typically 3–5 years in Australian conditions. Heat accelerates battery degradation — batteries in Queensland and WA often last closer to 3 years. Signs of a failing battery: slow cranking (engine turns over slowly on starting), dashboard battery warning light, needing jump-starts, or a battery more than 4 years old in a warm climate.