Why are my car battery terminals all corroded?

Alright, so you’re popping the bonnet after your Suzuki Swift wouldn’t crank over in the Pak’nSave carpark out in Rototuna, and you spot some weird white crud on your battery terminals. Looks like fluffy powder or crust. Sound familiar?

Corrosion on car battery terminals is pretty common around Hamilton, especially with all the stop-start driving down Heaphy Terrace or out towards Nawton, and with our crazy switch between cold foggy mornings and blazing summers. What actually happens is the battery releases a bit of hydrogen gas (all batteries do), and when it mixes with stuff like sulfuric acid… bam, you get corrosion building up right on the terminals. Some cars cop it worse than others too – we’ve seen everything from an elderly lady’s Peugeot 307 to a late-model Honda Odyssey in from Cambridge with the same problem. It doesn’t matter if it’s a Ford Everest or a purple Daihatsu Sirion, corrosion doesn’t discriminate.

Learn more about why corrosion occurs >

If you leave that build-up sitting there, it can slow down the flow of electricity between your battery and the rest of your car. That might mean your battery doesn’t charge properly, or you find yourself calling for a jump every couple of weeks. We always reckon – if you spot any white gunk, check it out sooner rather than later.

How do you know battery terminals are giving you grief?

Slow crank or won’t start: This is a classic. Last week a lady from Matangi brought in her Toyota Avensis, saying it’d struggle every cold morning, especially on those foggy Glenview starts. Big sign your battery’s not up to scratch – and corrosion could be the cause.

Battery runs flat quick: Get in your VW Golf, flick on the lights or the Bluetooth, and within half an hour the battery’s toast? Terminals so corroded they stop the battery charging properly. Seen it plenty on older Nissans and hybrids alike.

You can see the corrosion: White powder, sometimes bluey-green stuff, right on the terminals or the cable ends. Especially if you drive on rough spots like Pukete Road with all those potholes and speed bumps – vibration helps the corrosion along.

How to keep corrosion away from your battery terminals

Here’s what we tell anyone who comes into the workshop, whether they’re from Te Kowhai or Tamahere:

  • Give those terminals a regular clean: About every six months (maybe every WOF), check for build-up. Get in with an old toothbrush and a mix of baking soda and hot water. Just scrub it off, rinse, and dry before putting the cables back on.
  • Use a protectant: After you’re done cleaning, whack on a bit of battery terminal grease or spray-on protectant. You can grab this from most parts shops, and it’ll make the corrosion slow right down. Easy as.

Cleaning corrosion off your battery at home

The no-fuss way: mix up a tablespoon of baking soda in a cup of hot water. Dip a toothbrush or kitchen scrubbing brush in, and get stuck into the terminals – you’ll see the fizz working straight away. Got cables that are crusty too? Dunk the ends in that hot water. Rinse and dry everything well before you chuck it all back together. You can even pour the mix over the battery if you like, just watch you don’t splash it all over the engine bay.

(You can turn on CC for closed captions in the vid above if that helps.)

Other reasons your battery keeps going flat

Sometimes it’s not just corrosion. Could be your alternator’s on its way out, or there’s something slowly draining the battery when the car’s off (like a dodgy alarm). Or it might just be time for a new battery – most just don’t handle more than four, maybe five years with Hamilton’s rough roads and weird weather.

  • A faulty alternator or charging system
  • A drain on the battery even when the key’s out
  • Old battery – just needs replacing

Alternator Repairs    –    Car Battery Replacement  


Car Battery Terminal Cleaning & Repairs – Hamilton & Surrounds

Whether you’re grabbing groceries in Hillcrest, carpooling the kids from Morrinsville, or just want a hassle-free start every morning, keeping those battery terminals clean makes a huge difference.

If your battery’s looking a bit rough, or you’ve had to jump it more than once lately – no stress. Pop into the workshop. One of our techs will clean up those terminals properly. You’ll get a better spark, and your battery and the rest of the electrics will love you for it. If the problem’s bigger, we can sort alternators, starter motors, or swap your battery if needed. We play with all sorts: Toyotas, BMWs, Isuzus, big old Subarus, even the odd Mercedes van from Raglan.

  • Battery replacement
  • Alternator inspection and replacement
  • Starter motor checks and replacement
  • Full diagnostics for your ignition and electrical system

If you’re after reliable battery terminal cleaning or repairs in Hamilton, just give Grimmer Motors a buzz or swing by. Advice is always free over the counter – we’re just here to help keep you moving.

Book Now