Why Ballarat is hard on batteries
Sub-zero mornings, May to September
Temperatures here can dip below zero from May to September, and the average July minimum is 3.2 degrees. Cold weakens a battery's output just as a cold engine asks the most of it. A battery that started the car fine in February can be the one that clicks in June.
The cold cranking number on the label
Batteries carry a CCA rating (cold cranking amps, how much current they can deliver to start a cold engine). RACV says a replacement should have the same or a higher CCA rating than the car needs, and match its size and terminal positions. In a Ballarat winter, a battery that only just meets the minimum has nothing spare.
Foggy mornings, headlights on
Fog is common on autumn and winter mornings here, which means headlights on for the drive in. RACV counts lights or accessories left on among the usual causes of a flat battery, so a car without automatic headlights is worth a second look when you park.
The car that waits while you catch the train
If the second car sits for days while someone takes the V/Line to Melbourne, RACV lists long periods parked among the causes of a flat battery. Short trips of under 20 minutes don't give the alternator time to put the charge back either.
Battery or alternator?
Get both checked, because the signs overlap. RAC WA says slow cranking and fading dash lights can also mean a faulty alternator (the part that recharges the battery while the engine runs), and a multimeter test tells the two apart. RACV says the battery warning light on the dash can point to the charging system rather than the battery itself.
Ask the mechanic to test the charging system before fitting anything, or the new battery can end up flat on the next cold morning too.
Why the type matters on newer cars
RAC WA says AGM batteries suit hybrids and cars with stop-start. Some cars also need the new battery registered to the car's computer after it's fitted, and RACT notes some European cars carry a second, hidden battery. RACV warns that the wrong battery can seriously damage the electrical system, so the make, model and year matter when you send the job.
What a good written estimate for a battery shows
- The battery type (standard lead-acid or AGM) and its CCA rating, matched to what the car calls for.
- The result of the charging system test, not just the battery test.
- Any reset or battery registration the car needs, and whether it's included.
- The warranty on the new battery, written on the invoice.
- That the old battery goes to recycling: RAC WA says old lead-acid batteries go to a licensed recycling facility.
What you can do, and what to leave to the mechanic
You can
- Note when the slow starts began and whether they only happen on cold mornings.
- Look for blue or greenish residue on the terminals, or a swollen case, and mention it when the mechanic calls.
- Drive the car for at least 20 minutes once a week if it mostly sits, as RACV suggests.
- Lock the car even in the garage: RACQ says a keyless car left open stays awake searching for the key, and that draws power.
Leave to the mechanic
- Testing the battery and the charging system.
- Choosing a battery with the right type, size and CCA rating.
- Fitting it and doing any reset the car needs.
Where we'd start
If the battery is three years old or more, we'd have it tested in autumn, before the first hard frost, rather than wait for the morning it only clicks. NRMA recommends testing once or twice a year from about three years on. And if the car is already dead in the driveway, pick "Come to me": a mobile mechanic can test it and fit a new one where it sits.