Luke's Car Advice: Car Batteries

By Luke Caesar - General Manager - August 03, 2017

Luke's Car Advice: Car Batteries

In modern cars, the car battery is absolutely central to keeping the car running as it’s the power source for the whole electrical system.

With a flat battery, you won’t be able to release the immobiliser, use the power windows, or start the car. So you can see, it’s really essential that you keep your car battery in good condition.

Caring for your car battery

Here's some things you can do to preserve the lifetime of your car battery:

  • Check that you don’t leave the headlights or interior car lights on when you leave the car parked.
  • Have the alternator and battery charging system checked when you get your car serviced.
  • Have your car serviced on schedule. Poor engine condition increases the load on the car battery and shortens its lifespan.
  • If you don’t drive very often, buy a battery charger so you can keep the battery charged up. When your car isn’t in use, make sure the battery is at full charge, then disconnect the negative terminal.
  • If you are storing the battery, keep it charged and somewhere cool. Heat is the primary cause of battery failure as it promotes corrosion inside the battery.
  • Replace the battery every 5-7 years.

The rule of thumb for car batteries is ‘use it or lose it’. If a battery is allowed to discharge in storage, from not being used, this shortens its lifespan.

If you’re going to be away for a long period of time, ask a friend or family member to start your car and take it for a short drive regularly. The other option is to connect it to a maintenance charger while you are away.

My car won’t start!

Usually the first sign that anything is wrong with your car battery will be that you can’t start your car. What you need to do next will depend on what’s caused the battery to run flat, and the age of your battery.

We’ll have a look at 2 common situations and how to tackle them and get your car started again.

1. You’ve left the lights on for a few hours.

If you’ve left the lights on by mistake and your battery runs flat, the situation may be salvageable.

An older car can be jumpstarted (see below for instructions) to get you back on the road.

Ideally, when you need to recharge a car battery that’s flat, you should do so slowly to get the best result and maximise the battery life. However, usually you’ll need to get going right away, so a jump start makes sense.

2. You’re battery is actually dead - and you’ll need to replace it.

Car batteries don't last forever, so eventually your battery won't be able to store charge and will need to be replaced. When replacing your car battery, you need to dispose of the old car battery carefully as the materials it's made of are toxic

Ask your local mechanic about where you can recycle your old car battery.

How to Jumpstart Your Car and When Not To

Older cars are safe to jumpstart, provided the battery isn’t cracked or leaking.

If a car is newer than 2010, you could do more damage with a jump start than it would cost you to call roadside assistance, or have your car towed.

This is because the surge from a jump start can seriously harm the computers that make up the car’s electrical system, and this could cost you thousands.

However, if you have an older car, you can hook up to another car and get back on the road. Here’s how:

Jumpstarting Your Car:

When jumpstarting a car, you're dealing directly with the eletrical circuits of 2 cars, so you need to be careful to follow these steps to avoid harming yourself or your car.

1. Position the cars

If you can, bring the cars as close as possible, nose to nose. Put the parking brake on and turn off the car.

Put both cars into neutral or ‘park’ for an automatic car.

2. Determine which battery terminal is +/-

Next you need to know which terminal of the battery is positive and negative. The positive terminal is usually red with a (+) symbol. It will usually be slightly wider than the negative terminal, which is blank, with a (-) symbol.

Do not touch the metal portion of the jumper cable clamps against each other, or any part of the car except the correct battery terminal.

3. Attach Jumper Leads

The jumper cable clamps should be clearly marked as positive or negative, often they will be coloured red or black.

Start at the dead battery. Attach one of the positive clamps to the positive terminal of the flat battery. Then other end of the positive cable is attached to the positive terminal of the good battery.

Next, attach the negative cable to the negative terminal of the good battery.

Your jumper lead cables are live.

Do NOT touch the metal part of the last negative cable clamp to yourself, or any part of the car, except the negative terminal of the flat battery.

4. Grounding the ciruit

The last negative cable will be attached to any metal section of the car, away from the battery. The reason we do this is to avoid sparks and other potential hazards at the battery.

Before startung the car, make sure no one is near the moving parts of the car engines.

5. Start the car

Start the engine of the healthy car, and allow it to run for 1-2 minutes. Rev the engine slightly by pressing the accelerator.

Then start the dead car. If it doesn’t run the first time, try again, but don’t make more than 3-4 attempts to start.

6. If the jumpstart works:

Once both cars are running, you can disconnect the jumper leads, starting with the black negative cable clamps, then the positive clamps. Be careful not to let the clamps touch each other until all parts are disconnected from both cars.

Be sure to drive for 20-30 minutes to allow the alternator to charge your battery, so it will restart when you next switch it off.

What if the jumpstart doesn't work?

If a jump start fails, or the car battery goes flat again, and it’s 4-6 years old, you may need to replace it. You can also try another ground point for the negative terminal, and adjust the clamps to make sure they are properly attached to the battery terminals.

If you’re battery is reasonably new, there could be another problem, such as a faulty starter connection or ignition switch, faulty alternator, battery corrosion, or fuses that need replacing.

Car Battery Failure

Battery failure is failure is one of the most common causes of vehicle breakdown. There’s no warning signs before it happens. This means if your car battery is 5-7 years old, it’s a good idea to get it checked regularly, and to perform some basic battery maintenance.

Changing my car battery

If you can’t jump start your car, or the battery is 4-7 years old, it could be time to replace it.

Post 1990 model cars have electronics inside the car that are connected to the battery, even when it’s not in use. If you disconnect the battery, this could affect the software memory, and your settings could be scrambled.

When you have your battery changed over by a mechanic or roadside assistance, they’ll use a ‘memory-minder’ to ensure that this does not occur.

Basic car battery maintenance:

Your car battery is found in a heavy duty plastic case, and two terminals connect the positive and negative wires to the car.

The positive terminal of the car battery connects to your car’s power distribution centre which provides power to your car and it’s computers.

The negative terminal connects to the chassis to complete the ground circuit. Both connections are essential for power to be fed to your car.

If you are removing the cables on the battery, take a picture before you do anything, so you don’t reverse the positive and negative cables when you reconnect the battery.

What to do with a flat battery:

If your car battery becomes discharged, sulfate crystals may form, decreases the battery capacity and ability to recharge. If your battery does become flat, it’s best to charge it slowly with low amps to prevent sulfation.

Of course, you might not have this luxury as you’ll usually only notice that your car battery is flat at the very moment that you need to drive somewhere, so you’ll restart it using jumper leads.

Preventing Corrosion

Keeing battery terminals free of corrosion is important to prolong the life of the battery. Every 6-8 months, remove the connectors and scrub them using either baking soda, or you can even use cola.

Any corrosion that has formed will be acidic, so you use a mixture of baking soda and water to neutralise the acid, before scrubbing the corrosion away with a stiff brush.

Once dry, put a small amount of petroleum jelly onto the terminal to protect it from future corrosion.

Two types of car battery

A car battery is usually a 12V ‘lead-acid’ battery.

The purpose of the battery is to power the lights and start the car. After this the power needed for the car and it’s accessories is generated by the engine.

The exception to this is some models of performance car, and electric vehicles, which have a lithium ion battery, but that’s a topic for another time. And a hybrid car like the Toyota Prius has a nickel metal hydride battery that’s used to help run the car.

There’s 2 main types of car batteries: a ‘wet cell’ or ‘flooded’ battery, or an ‘Absorbed Glass Matt’ (AGM) or ‘dry’ battery.

Wet Cell Car Batteries

‘Wet-cell’ car batteries are generally cheaper, and don’t require maintenance. It’s made up of plates of lead (Pb) and lead dioxide (PbO2) suspended in an electrolyte solution of sulphuric acid. The positive plate and negative plate are kept separate in sealed compartments.

Dry Cell Car battery

An AGM (absorbed glass matt) battery doesn’t have fluid, the electrolyte is absorbed in a glass matt separator, which allows the battery to be mounted in any direction, it doesn’t have to be kept upright.

Both types of batteries have 6 cells. As the battery discharges, the lead and lead dioxide is converted to lead sulphate.

If you drive at least once a week for a steady hour, your car battery should stay charged.

Can I buy a second hand battery to replace a dead battery?

Searching on eBay or Gumtree you’ll find that there are lots of second hand car batteries for sale. Should you take the cheaper option, or fork out for a new battery?

The answer lies in how long you’ll be driving the car for. If you’ve got an old car that you’re just trying to squeeze a few more weeks or months out of, a second hand battery might be your best bet to avoid spending too much.

You would want to find out how it’s been used, and whether it’s still under the warranty period. If you’re going to buy a secondhand battery, then a wrecking yard is a good place to go.

Cars can be written off with an almost new battery, so you could score a good deal that will last for 4 years or so.

Recycling your old car battery

When your battery does get replaced, whether you do it yourself, at the mechanic, or by a roadside assistance service, it pays to know how it’s going to be disposed of.

Car batteries contain toxic lead which is dangerous if it gets into the environment, to both humans and animals, as well as 2-3 litres of sulphuric acid. The good news is that if properly taken care of, 96% of materials comprising the battery will be recovered, and the acid is neutralised.

Check that your car battery will be responsibly recycled at a location near you and do that little bit extra to protect the environment for the future.