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Current affairs: How do I maintain my car battery?

I read your story on keeping batteries charged in parked vehicles. I was wondering if batteries need maintenance, even if a car gets used all the time? My battery is supposed to be maintenance-free. – Jocelyn

With great power comes great responsibility, if you're Peter Parker.

But if you're a driver with a maintenance-free battery, experts say the biggest chores are getting the terminals checked to make sure they're clean – and making sure your battery doesn't get drained in the first place.

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"The life-span of automotive batteries is greatly influenced by how they are used, or abused," says Stephen Leroux, automotive professor at Centennial College in Toronto. "Every time a battery becomes fully discharged, the life expectancy of the battery decreases."

To put it plainly, every time you leave lights or a radio on overnight and the battery dies, the battery gets damaged. "The battery builds up heat as the power drains, and the elements inside start to deteriorate," Leroux explains.

With sealed, maintenance-free batteries, you don't have to check electrolyte levels and top them up regularly with water. In fact, you can't add water to them.

That's a change from the old-fashioned flooded cell battery – the water inside was electrolyzed to hydrogen and oxygen and evaporated. That meant you had to add water.

"Maintenance-free refers to the fluid level – they have a gel inside to maintain the water," says Patrick Brown-Harrison, instructor at SAIT Polytechnic in Calgary. The change was made "to reduce service requirements and to keep contaminants from being added to the fluid," he says.

But even with maintenance-free batteries, you still need to have the terminals checked to make sure they're tight, properly connected to the battery and free of corrosion. If there's corrosion there, they need to be cleaned.

"Batteries still require terminal service. Traditionally this is done as part of yearly service," Brown-Harrison says.

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Brown-Harrison says it's better to leave this to a professional.

"It's possible to strip or damage the bolts," he says. "And if you're not paying attention it's possible to neutralize the battery acid."

Leroux says cables also need to be inspected for cracks in the insulation, and the battery case should be checked to make sure it's clean.

"Batteries sometimes vent and the vapours settle on the battery case in a liquid form," Leroux says. "The liquid may be conductive or corrosive and this can lead to the battery becoming discharged."

And that fluid could also corrode any wiring harnesses near the battery – so it should be cleaned off, Leroux says.

In addition, dust or debris on the battery case can act as a conductor, which can discharge the battery. Leroux suggests cleaning the battery case with baking soda and water.

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When getting the battery inspected, Leroux suggests also getting the drive belts, the belt tensioner and the alternator checked.

"They all help maintain the battery at an adequate state of charge," he says. "Alternator output will need to be checked to make sure it's capable of supporting the electrical loads exerted on the battery.

"Dealerships and service centres usually offer a fall inspection that will check these before winter hits," he says.

Have any battery tips to share? We're hoping for a, er, charged discussion below.

If you have any repair or maintenance queries for Jason, send him a message at or contact him through Twitter: @JasonTchir

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