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8 tips for looking after your battery

By David Bonnici, 23 Apr 2020 Car Advice

How to maintain your car battery and what to do when it goes flat.

Battery light

Your car's alternator doesn't charge a flat battery

Contrary to popular belief you can’t charge a flat battery with the vehicle’s alternator by driving around or idling the engine. The alternator doesn’t recharge a battery, it tops up what it uses, which is called surface charging. Surface charging a weak battery will shorten its life.

Proper recharging can only be done with an appropriate multi-stage charger. A good charger can cost less than a new battery so you’re already getting your money’s worth. Watch the above video for more information on how to correctly charge your car's battery.

Don't disconnect the battery when not using your car

If the car isn’t being driven for more than a few weeks the battery will eventually go flat, but don’t disconnect it to save power.

Most cars now have clocks, alarm systems and trip computers that draw on the battery even when turned off, and might have issues working again should you totally disconnect the power for a long time.

Batteries slowly self-discharge even when not connected to a load anyway, so quick charge from time to time will keep the battery alive.

Battery cables don't hold the battery in place

Even if it’s a snug fit and held down by stiff battery cables, make sure your battery is securely clamped with a hold-down. A loose battery can get damaged or cause damage to other items under the bonnet or worse still short against metal and cause an explosion.

Best batteries for hot weather

If you live in a hot climate you’re better off getting an older style non-sealed battery so you can top up the water levels to stop the plates drying out. Maintenance-free batteries are sealed meaning you can’t top up the water if they start drying out.

READ NEXT: Hot-weather car and driving tips

Spare battery

The right water for topping up batteries

If you need to add water make sure you use distilled, de-ionised or de-mineralised water. Tap water contains minerals that can block pores in the battery plates which makes them dry out and fail.

Maintenance-free batteries aren't maintenance free

Even so-called maintenance-free batteries need a bit of looking after including making sure the terminals are clean, brushing away any corrosive residue and checking the alternator charge rate from time to time.

READ NEXT: How to jump start your car

Is that powdery stuff on the battery a bad thing?

Don’t worry if there is corrosive powder on the terminals as all batteries get it over time due to a reaction between the metal and electricity. Just be sure to remove it from the terminals and cable clamps with a stiff brush to ensure good connectivity.

Car battery powedery residue

What does the battery warning mean?

The battery light on your dashboard isn’t telling you your battery is faulty, it’s warning you that the alternator isn’t working and the car is being powered by the battery alone.

READ MORE: What does the check engine light mean?