THe Commodore SS-V’s battery is boot-mounted

You have to feel sorry for a car battery.

It’s crammed in under a hot bonnet, has to keep on working when the rest of the car is idle, must perform Herculean tasks to get the vehicle going, is often left without exercise for long periods… then gets abused when it gives up after two years.

A battery’s primary assignment is to start the engine, but it also provides extra power for ignition, lighting and accessories when their combined load exceeds the capability of the charging system, such as when the engine is idling.

It also provides power when the engine – thus the charging system – is switched off.
Have you ever thought about the stuff that needs power all the time?

Remote central door-locking needs a working receiver to know when you press the button.

Then there are security systems, audio system memories, clocks; even the computerised fuel injection wants some power at all times.

The demand placed on a battery by a modern, well-accessoried vehicle means that it may not last as long as it used to.

It’s now often said that even a well-maintained battery lasts for about two years, but there are many variables that will influence life span.

For example, the battery of a car that sits idle for weeks may not last as long as one that’s exercised every day.

Here are some things to consider when buying a new battery  will:
Type
Low-maintenance and maintenance-free are most common. Advantages of maintenance-free batteries are said to include longer life, greater overcharge resistance, faster recharging and less terminal corrosion. Plus, you never have to do anything with it!

Some argue that non-sealed batteries are better, particularly in warmer climates, as you can add water as required and test the specific gravity with a hydrometer.

You may come across something called a deep cycle battery. Regular car batteries are designed to produce high initial cranking amps to start an engine.

Deep cycle batteries are designed for prolonged discharges at lower amperage. They’re used in tandem with a regular battery in some vehicles, including electric winch-equipped 4WDs and in recreational vehicles to power the accessories.

Now widely available are spiral cell batteries. Claims for them are that they offer double the life of conventional batteries, a higher reserve capacity, low self-discharge and good vibration resistance. Pioneered by Optima, other companies make versions, including Exide. Rolls of lead plates are tightly compressed into spiral-wound cells, providing more than twice the surface area for the lead alloy electrodes compared to conventional designs. The catch: they cost more than conventional types.

Cold Cranking Amps (CCA)
This is a measure of a battery’s ability to start an engine and some say is the only figure that realty matters.
Some people like to buy a replacement battery with a CCA that exceeds that manufacturer’s recommendation (see your vehicle’s handbook) for a bit of extra oomph; the wisdom of doing this is debatable, except in colder climates where increased power is required to get a sluggish engine going. A battery’s not at its most efficient in the cold, either.

Exide says a battery needs 55 per cent more power to crank an engine at zero degrees Celcius than it does on a nice 26-degree summer’s day.

The right CCA depends very much on the engine type. A used import one-litre Starlet is going to need way less starting grunt than a big 4.2-litre Nissan Patrol diesel.

Reserve Capacity (RC)
This represents the number of minutes a fully charged battery at 26.7 degrees Celcius (or 80 degrees Fahrenheit) can be discharged at 25 amps until the voltage falls below 10.5 volts. More RC is always better.
Size

There might be room for a battery larger than the manufacturer provided. Larger may mean gruntier, but make sure a bigger one really will fit properly, that the cables will connect without being stretched, and that the terminals or cables won’t touch the closed bonnet.

Warranty
Check the warranty period and conditions. These usually involve some kind of pro-rata arrangement, meaning the older the battery is before it develops a fault the more you have to pay towards a replacement.