If you need to replace the battery or connect it to a battery charger outside the car (for example, for overnight charging), then it will have to be removed from the vehicle. Why would you want to replace a battery? Well, the battery powers not just the ignition and lights, but also supplies the power for the heater fan, heated rear window, stereo, fuel injection and other computer-controlled functions of a modern car. If the battery is not up to par, the first you will become aware of it is when the starter becomes sluggish or refuses to operate altogether.
BATTERY DOS & DON’TS
√ DO keep your battery clean, fully topped up with ionized (distilled) water and properly charged.
⊗ DON’T ever put water straight from the tap into your battery – it will destroy it.
√ DO replace your battery on a regular basis. Your car will thank you for it!
Remove the negative (black) terminal first using a spanner to undo the securing nut, then the positive (red lead) [A], to avoid causing any sparks. With the battery disconnected, the clamp which holds it in place can be undone [B and diagram, HOW TO DISCONNECT AND REMOVE THE BATTERY]. Often, these can be corroded and may need oiling before trying to undo the nut. Different cars employ various methods of clamping down the battery, such as fitting over the battery or clamping the lower lip of the battery to the battery tray, as shown here.
With the battery clamp undone, lift the battery from the car and check the battery tray for corrosion. You do not want your new battery falling out of the engine bay! Make sure your new battery has the same type of terminals as your old one. There are square terminals, which the leads bolt to, and round ‘post’ type terminals, which the leads clamp onto. Check, as well, that the positive and negative terminals are in the same position. The leads are connected to the new battery (positive first, then the negative) before the battery clamp is tightened. Add some form of terminal protector to prevent corrosion[C]. This can be bought from accessory shops, but petroleum jelly works just as well. Without protection the terminals, especially the positive one, will corrode and become difficult to remove in future.
Continual short journeys, often with the headlights on, have weakened this battery.
To remove the battery clamp from the battery tray, carefully place the socket over the nut , then twist until loose. The nut may need lubricating if there is any visible corrosion.
Charging the battery
You can charge a battery using a charger in situ or out of the vehicle (for example, overnight). Whichever method, the battery leads must be disconnected before con- necting the charger.
Some chargers can be set to fast charge or ‘trickle’ charge for a slow charge over long periods, while others, usually cheaper models, are only set to trickle charge. It is better to trickle charge but depends on how quickly you need the battery up and running. Adjust the charging rate as necessary.
TIP: When using a battery charger with the battery still in the car, disconnect your battery’s leads before charging.
pic 5 Connect the red positive charger lead to the positive battery terminal and the black negative lead to the negative battery terminal. Finally, connect the charger to a mains supply and switch on.