Winterizing your Vehicle—How to Prevent a Dead Battery

This is part 2 of our Winterizing Your Car series that will focus on the battery and charging system in your car. Check back frequently for more articles about winterizing your car!

Depending on where you’re located, the weather might just now be getting chilly at nights or you might already be in the throes of winter and under a foot of snow. Or, for those of you in the southern hemisphere, spring is in full effect and this article likely won’t apply to you for another 6 months! However, if you’re like most visitors to this site, you’re probably somewhere in North America and therefore know that winter is right around the corner. Not only does cold weather put a stress on our homes and heating units, it also adds additional stress to our cars. Many of us have had to deal with a dead battery on a freezing cold morning or have been late to work because the windshield was frozen over and wouldn’t defrost quickly enough; a little bit of maintenance and preparation can go a long way to preventing some automotive related headaches.

Probably THE most common cause of breakdowns during the winter months is a dead battery. I’m sure that just about everyone has tried to start their car on a cold morning in early winter only to hear that all-to-familiar sound of a car that won’t crank up because of a dead battery. Many people don’t realize it, but there are a lot of simple steps that you can take to help avoid that situation. Your car’s battery is but one part of the electrical system on your car. Everyone knows WHAT a battery does, but to understand how to take care of a battery, you need to know how it works in relation to the charging and electrical systems on the car.

Generally speaking, various parts of your car require a certain amount of electricity. Your headlights, spark plugs, radio, seat heaters, etc., are all powered by electricity that comes from your battery. All of those components would quickly drain your battery if there wasn’t another component in place that continually charged your battery. That’s what the alternator is for. The alternator converts mechanical energy that it draws from the engine and converts it to electricity for the battery to use. When the engine is running, a belt drives the alternator to produce this current to be used by the battery. All of the electrical components on your car, from the smallest sensor to the brightest light, require a certain amount of this electricity to operate. Auto manufacturers select batteries to use in their cars that will be more than strong enough to run all of the electrical components so that we don’t have to worry about overloading the battery and using too much electricity. So how does all of this relate to cold weather? Cranking up your car is the heaviest electrical load you’re likely to ever put on your battery. For that reason, one of the most important measures of a car battery is what’s called Cranking Amps (CA). Simply put, cranking amps represent the amount of electricity a battery can put out when it’s just sitting in your car and not being charged. Another very important battery measure is called Cold Cranking Amps (or CCA). CCA are identical to CA except that CCA are a measure of a battery’s output at a colder temperature. CCA ratings are always LOWER than CA ratings because batteries are simply less effective at lower temperatures. The chemical reactions that go on inside a battery that help produce electrical current proceed slower as the temperature drops, effectively limiting how much current a battery can produce at a given temperature. Once again, auto manufacturers take this into account when selecting batteries to use in the cars they make, but like most car parts, batteries do slowly wear out over time. We don’t necessarily see that slow degradation occur, but it happens. That’s when problems arise.

Let’s say that your car requires a minimum of 500 amps to crank up. Your battery is rated for 600CCA and 700CA. Over 4 years of use, your battery starts to degrade to the point where it’s now putting out 480CCA and 550CA. If it’s reasonably warm outside, your car will still crank up just fine because you’re only using 500 amps out of the 550 available. However, when the temperatures drop overnight and it’s freezing cold the next morning, the car won’t crank up because at the lower temperature your worn out battery can only put out 480 amps and your car needs 500 to start. This is what happens to millions of people every winter. The easiest way to prevent this from happening is to replace your battery before it ever happens. There are plenty of shops and auto parts stores that will test your battery for you at no charge. If it’s showing signs of age, go ahead and replace it before it gets very cold outside. Additionally, every battery has a manufactured date code stamped onto the battery.

Here’s a good link that explains how to dechiper that date code to determine when that battery was manufactured:

Most batteries that are over 5 years old are likely due for replacement soon and should at least be checked periodically. A visual inspection of your battery once every month will also go a long way to preventing an unexpected dead battery. Check the cables to make sure that they’re tight. Check for any signs of corrosion (usually a bluish-white powdery substance) on the battery posts and on the battery cables—you can clean most corrosion with a solution of water and baking soda and a wire brush. Check the water level inside the battery cells and add a little bit of water if needed. Check the condition of the alternator belt and make sure that there’s an appropriate amount of tension on the belt; a loose belt could prevent the alternator from converting enough mechanical power to electrical current to keep the battery fully charged.

In addition to checking the various components of the charging system, there are some other things you can do to help prevent a dead battery, particularly if you suspect that your battery is getting near the point of needing to be replaced. If possible, park in an area shielded from cold weather (i.e. a garage). Also, avoid short trips (i.e. 10 minutes or less). Your battery gets stronger the longer it’s charged in a warm operating environment. Several short trips prevent your engine bay from heating up completely and don’t allow your alternator enough time to fully charge the battery. If you do have to take a lot of short trips, try to leave the car running for a few extra minutes to let it get up to its full operating temperature, particularly if you’re using a lot of accessories like heated seats or the rear defroster or headlights. It not only charges your battery, but it also helps other parts of your car as well.

As you can see, taking care of your battery is quite easy and should only take a few minutes of your time. Doing so will greatly reduce your chances of having to deal with a dead battery at an inopportune time. We hope that this was an informative and interesting look at how to maintain your car’s battery and charging system. Be sure to look for more articles about preparing your car for winter. Check out our informative article about making sure that your tires are ready to go for the cold weather!