Be kind to your battery as winter takes hold

It is frustrating to head out on a frigid winter morning, only to be greeted by the dreaded click-click-click from a dead battery. But winter’s cold, cruel grip isn’t the only cause of battery failures, as the heat of summer days can drive just as many batteries to the recyclers.

Knowing how a battery and charging system works can help you avoid those early morning commute disasters.

If the battery is over three years old, get it tested before the real bite of winter’s cold hits. It’s a relatively easy and quick operation; most shops can do this at no extra charge when completing seasonal maintenance.

A battery has two basic tasks — hold electrical power in reserve, and deliver that energy to the engine’s starter on demand. The other crucial part of the equation is the vehicle’s charging system, specifically, the belt-driven alternator.

On a winter day, when you start your engine, the battery is drained of a substantial portion of its charge or power reserve. As soon as the engine catches, the alternator starts recharging the battery, but that electric dynamo must also power all other electrical demands, such as the heater, lighting, defroster, fuel pump and injectors, and so on. And the output of the alternator is dependent on engine speed, among other things.

If you get your slightly older vehicle started and make a few short trips at low speeds — say, in stop-and-go traffic — with everything electrical powered up, chances are good that your battery will not fully recharge between starts. So the next day, after your vehicle sits all night in sub-zero temperatures, the battery might not have enough juice to get things going the next morning.

Newer vehicles are often equipped with charge-sensing systems that can let onboard computers bump the recharge power back to the battery to prevent this, but many entry-level rides and older vehicles, don’t have this.

The worst thing you can do to a battery on a frosty day is make two or more short runs that don’t let the engine fully warm up, and have everything electrical turned on full tilt. If you absolutely can’t avoid these scenarios, turn the HVAC blower fan down a few speeds as soon as your windows have defrosted, and leave the fog lamps off — unless you’re driving in fog, they don’t do any good anyway.

Also avoid letting the engine run at lower speeds, as the alternator’s output is dependent on engine speed, and switch to a lower gear when you’re stuck in slow traffic to keep the revs up a bit. For the last couple of blocks of your trip, turn everything electrical down (or switch it off, if possible) to let as much of the alternator’s power get to the battery.