January 4, 2006

Starting your car on a cold morning
by Jim Kerr

Cold winter evenings, long winter nights, and bone chilling wind chills make curling up with a blanket and warm drink very appealing. Unfortunately, your vehicle doesn't have that option. Many of them sit outside, waiting in the cold to be called into service at a moment's notice. While most of the time, everything works fine, occasionally they just don't start.

One of the most important parts of your vehicle during cold weather is your battery. Battery life can be as short as a few months, while some may last 7 years or longer. Outside temperature and charging system operation are major factors in determining how long a battery will last. Hot southern climates cause battery life to be very short; one year or less. In our climate, most good quality batteries should last 4 to 5 years.

Almost all automotive repair shops have the equipment required to test battery condition. Testing is a two-step operation. First the battery is checked for it's "state of charge. To properly test a battery, it must have at least a 75% charge. Any battery with a lower "state of charge" will fail the next test even though it may be good.

Next, an electrical load is placed on the battery using a battery load tester. Power is drained out of the battery for 15 seconds at a rate determined by the size or capacity of the battery. At the end of 15 seconds the battery voltage must remain above 9.6 volts. This indicates the battery is in good condition and should provide starting power during cold weather. A battery that drops below 9.6 volts at the end of the test may work fine in warm weather but won't start an engine when the temperature drops.

There are newer type battery testers that can test a battery even though it is mostly discharged, but even these testers sometimes require the battery to be charged before an accurate evaluation of battery condition can be performed.

When buying a new battery, drivers should buy the best battery that will fit in their vehicle. This doesn't mean the most expensive battery. There are only 4 or 5 major battery manufacturers in all of North America and they are all very competitive when it comes to quality so look for a battery with the best warranty and a supplier that backs that warranty.

Better batteries will have a high power capacity. A common method of rating batteries is by using their Cold Cranking Amperage capacity (CCA). This rating is a test of the battery's ability to supply power for 30 seconds at -18 C while staying above 7.2 volts. It sounds complicated but all you have to remember is the higher the rating for the CCA, the more power your battery will provide in cold weather.

Typically, smaller vehicles use a battery with a rating of 450 CCA to 650 CCA while vehicles with large engines or lots of electrical accessories may use batteries with a rating of 900 CCA. The amount of lead inside a battery is the major factor in determining the CCA rating. The heavier the battery, the more power it can supply.

Keeping a battery in good condition involves cleaning the battery cables, making sure the charging system is charging at the correct rate, and keeping the battery charged during storage. A battery that is allowed to completely discharge 4 or 5 times will most likely need replacement. This happens because the lead coating on the plates inside the battery starts to fail when a battery is dead; Four or five complete discharges and the battery doesn't work well.

Freezing a battery will also destroy the lead coating and make a battery useless. Fortunately, a fully charged battery will not freeze until the temperature drops far below -50 C, so as long as the battery is not discharged, it won't freeze in our climate.

Environmentally, batteries have had a bad reputation, but 99% of a lead/acid automotive battery can be recycled. Battery manufacturers would rather melt down recycled batteries than use new materials because it is cheaper for them. Please help save our environment by disposing of your old auto batteries where they can be recycled.

Jim Kerr is a master automotive mechanic and teaches automotive technology. He has been writing automotive articles for fifteen years for newspapers and magazines in Canada and the United States, and is a member of the Automotive Journalist's Association of Canada (AJAC).

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