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How to maintain your truck or car battery

The average lifetime of a vehicle battery is around 3-4 years, but it depends on their maintenance, operating conditions and how frequently they are used. If your battery fails at a critical time it can cause a lot of inconvenience, cost and even danger as it could leave you stranded in a remote area.

Batteries don’t usually expire suddenly, it’s more likely that they will lose their capacity to perform over time. This degradation in performance is caused by:

  • Vibration in the vehicle
  • Changes in temperature and humidity
  • Constant charging and discharging

Not maintaining the battery or exposing it to extreme climate will accelerate its failure. The first clue that a battery is nearing the end of its life is if it struggles to turn the engine over. At this point, you could get the battery load tested and the alternator output checked. This process will take 15-30 minutes. If you get a clicking sound from the starter motor, the battery is no longer storing enough charge to crank the engine.

Another sign that your battery is about to expire is if it starts to bulge.

If the battery warning light comes on on your dashboard, this doesn’t necessarily mean your battery is faulty; it means that the battery is not getting any charge from the alternator. Your vehicle will continue to function until the battery goes dead. However, it’s not good to let the battery go dead as discharging a vehicle battery fully shortens its life.

How does cold weather affect battery performance?

Batteries work better in warm climates. When the temperature is in the twenties, you will get around 100% power output from the battery. At freezing point, though, the battery could have lost more than 35% of its power. At -17C, it could have lost up to 65%.

How do you maintain your battery?

If your battery is in a battery box like this, it will resist corrosion

Some batteries are low-maintenance or ‘maintenance-free’ but that just refers to the battery itself and means you won’t have to top up the electrolyte fluid.

This battery has a battery acid level indicator

You still need to check other things every month:

  1. Clamps that hold the battery are tight
  2. Cables are firmly connected to the terminals and are not crimped or pinched
  3. Terminals are not corroded
  4. Electrolyte levels are high (if required)
Corrosion around the terminals (the blue fuzz) should be cleaned off, but be careful with it as it is crystalised acid

Truck drivers should be doing a visual check of items 1-3 every pre-trip inspection, plus check any pins or bolts on external clamps.

Truck batteries are often much more exposed to the elements and need to be checked more frequently.

If you are leaving your truck or car for a while, it’s best to trickle charge the battery to keep it fresh.

A solar-powered trickle charger like this is ideal for trucks in a yard
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Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers' Guild

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