Beat the battery blues

Spare a thought for the battery in your vehicle.

The lead-acid battery has an impressive survival record. For more than a hundred years the lead-acid battery has been part of the motor car. Engineers and scientists have been trying to find something better, something lighter, more efficient. But so far they have not come up with a practical, economical alternative.

A car battery is a device in which chemical reactions make an electrical current flow from one battery terminal through an external circuit to the other terminal when the battery is discharging.

When the battery is being charged, the process is reversed: an external current source - the alternator or a charger - forces current through the battery in the opposite direction and the chemical reactions now return the battery to a charged state.

The primary purpose of a car battery is to supply current to the starter motor to crank the engine at start-up and to power up the ignition system at the same time so that the engine will start.

It is therefore natural to point an accusing finger at the battery when the engine doesn't start.

If it cranks the engine lustily and yet the engine doesn't start, the fault lies elsewhere .

Even when the starter motor begins to emit slow, wheezing noises, it is by no means certain that the battery is at fault.

The problem might be located in the starter motor itself, or in the heavy cables carrying the current to and from the starter.

And should it be established beyond doubt that the battery is the problem, the question still remains: did the battery really expire because of old age and neglect?

Or is it just temporarily out of breath because the alternator can't keep it fully charged? In the latter case it would be pointless to buy a new battery; it is also going to run out of breath soon.

What can we do to avoid expensive and infuriating battery blues?

l Buy the biggest, meanest lump that will fit into the available space in your car.

l A battery can die suddenly but that is rather unusual. There are usually early warning signs, most noticeably a sluggish starter.

l The worst thing you can do to a lead-acid battery is to leave it in a discharged state for weeks.

l A battery charger will quickly pay for itself by extending the life of car batteries.

l Excessive heat shortens the life of a battery.

l Keep the electrolytes topped up to the indicated level on older batteries. Use only distilled water.