With new technology to power up the complex electronics driving today’s new cars, it is hard to believe that the humble battery is still the cause of most breakdowns reported each year to the motoring organisations. Or is it?

So many simple power consumers such as lights and heaters can adversely impact on the battery and alternator’s ability to provide constant energy, particularly in winter, that the nominal output of the alternator can be easily exceeded by the time you have reached the first traffic jam.

And we are only talking about modern cars with healthy batteries. More than one million call outs last year to the AA and RAC were due to flat batteries that had been neglected or were simply too old. But the effect on modern batteries of too many power drainers left on at the same time can also be costly, both in terms of reliability and excessive fuel consumption.

Sound advice from the battery experts at VARTA is to use heavy current consumers like heated screens, fans and seats sensibly, turning them off as soon as they have done their job after starting your winter journey.

In a Volkswagen Golf the alternator produces almost two kilowatts. To see how this can easily be eroded, lighting, including brake lights and instrument panel, requires around 200 watts, rear window heater up to 400 watts and a massive 1,000 watts for a heated windscreen. The heater fan at its highest setting will consume another 400 watts and heated seating 100 watts per seat..

These consumers already exceed the nominal output of the alternator, without any allowance made for engine electronics. The fuel pump, injection, ignition system and Lambda probe can nowadays guzzle up to 500 watts.

Sitting in traffic with the engine idling and too many current consumers switched on places an even greater strain on the car battery in winter. The colder it is, the more then engine will have difficulty turning over with its dense oil. The current-producing chemical processes at work in the battery will be more sluggish too, and it will be harder to start the engine even when the battery is fully charged.

So conserve power whenever you can. Turn down the fan as soon as the windscreen had cleared and the rear window heater when the frost has cleared. Switch off you heated seat when you are warm enough and avoid using fog lights unnecessarily.

If you are still not convinced, consider the cost implications. The car’s power must be generated by the alternator, which also needs power. In stop-start traffic there is little output required by the engine, and the power required by the alternator adversely affects fuel consumption.

Anyone who frequently drives with lights, windscreen, seat heaters and other accessories switched on can get through between half and one litre of extra fuel over a 60 mile journey.

It is also wise to check the condition of your car battery before the onset of winter. Many VARTA stockists offer this service free of charge.

If you need a replacement, VARTA’s range of premium quality BLUE dynamic batteries for European cars and ASIA dynamic for Japanese cars use the same calcium-silver technology as fitted to most new vehicles today. Calcium-silver batteries provide 20 per cent longer service life than conventional lead acid car batteries.