The cold is once again taking its toll on car batteries. Some are no longer able to start the engine at sub-zero temperatures. Could it be that the power consumption of the lights are to blame? Don’t worry, headlights and other lights are not the bad guys here.

Admittedly, it’s often older people who fear a flat battery, and therefore gladly drive without lights for as long as possible. This group of drivers were deeply scarred by 6-volt electrical systems and DC generators. And they could still forget to turn off the lights, really leaving the battery flat.

Today, clever circuits and acoustic signals make sure that this doesn’t happen anymore. And modern AC generators not only charge at idle speeds, but also produce up to ten times more energy than their predecessors. Nevertheless, many drivers including young ones tend to think that lights have a disastrous impact on a healthy on-board electrical system.

Compared to the biggest power consumers in cars, lights are hardly worth mentioning. The halogen version takes 150 watts. Xenon and LED take approximately 100. Many people are not aware where to find the real guzzlers. The fan heater gobbles up around 800 watts. The rear window heater isn’t far behind. And two heated seats easily get to the same level as the lights.

But then all these loads aren’t really the problem. Flat batteries mainly occur for three reasons. First, they may be old and worn-out. As with all things, there are big differences in quality when it comes to car batteries. Some give up the ghost after just two or three winters, and others last for seven years. Sometimes, people cut corners when it comes to the capacity of the battery. Breakdown mechanics have found that the combination of the widest permissible tires and the smallest possible battery is quite common.

Another reason is an unfavorable driving profile. If the car is only going a few miles on a cold winter morning, the generator won’t have a chance to get the battery back to its full charge, considering the charge it gobbles up during start-up – the starter easily uses about 2000 watts – and with all the guzzlers switched on that I mentioned above. This applies in particular if there are many traffic lights, traffic jams or other places where the engine is idle. Then the battery will lose some charge every day which will no longer be topped up.

If your set of wheels still messes you about even with a new high-quality battery, there may be a problem with the charge controller. Then you should get your battery’s charging voltage checked. It shouldn’t be below 13.2 volts – with the lights switched on, of course. Because that never hurts.

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