Your Corner Wrench: Signs your vehicle needs a new battery

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Just because you’re rewarded with the click-click-click death-knell sound when you hit the ignition on your daily driver doesn’t necessarily mean it’s time for a new battery. A charging system problem can give the same symptom, leading to an unnecessary battery purchase if an easy diagnosis isn’t completed.

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No matter how expensive or advanced your ride might be, it’s still started by an old-style lead-acid 12-volt battery. When operated year-round in our lovely weather, these units have an average life expectancy of between three and five years, and after three years on an original or replacement battery they should be tested annually. Most shops will provide this test for regular customers upon request at no charge. Other than that, you shouldn’t pay any more than $25 for it.

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Your Corner Wrench: Signs your vehicle needs a new battery Back to video

The test is usually referred to as an AVR test (it stands for “alternator voltage regulator”). With the right equipment, a tech can apply a measured electrical load to the battery and monitor the results. He or she can also display the output of the alternator and the amount of power the starter draws when engaged.

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Slow cranking to start should be your first sign that you may have a battery problem. A defective starter can give a similar symptom, so having the battery tested before replacing it is a good idea.

A case of a non-responsive battery can be caused by an internal fault or from lack of recharging power from the engine’s alternator. An easy method of detection as to which is the cause is to restart the vehicle with a safe jump-start or boost, letting the engine idle to warm up with the booster pack or power-donor vehicle still hooked up to the dead battery. Then remove the cables and let the engine continue to idle. If it a check engine light comes on and/or the engine eventually stalls out (after five or so minutes) the probable cause is lack of power to the battery from the charging system.

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A fuel-injected engine can run without a functioning battery but needs a continual source of electrical power to keep fuel pumps, injectors, computers, and the like operating.

If a vehicle with a dead battery is exposed to extremely cold temps (think any ‘balmy’ January or February chiller) the liquid electrolyte fluid in the battery’s cells can freeze and expand. This will almost always relegate the battery to the recycling center. Before even attempting to boost a possibly frozen battery, carefully check its sides for bulging caused by any frozen electrolyte. This can damage internal cells and weaken the case causing acid or fume leaks increasing the risk of a fire or explosion.

Overcharging can kill a battery quicker than under-charging it. When a voltage control system fails in an alternator, it can quickly overheat the battery and literally boil the electrolyte away. This condition is usually marked by strong sulphur-like odours and a battery that’s warm to the touch. Never try to boost a vehicle in this condition as those smells indicate a strong presence of very volatile fumes.