Auto electrical and batteries
Car Battery Testing in Moorooka
A voltage reading on its own does not tell you whether a battery is any good. It tells you how much charge is in it right now, which is a different question. We load test or conductance test the battery at our Moorooka workshop and check the charging and starting side at the same time, so the answer covers the whole system. Call 0402 723 464.
Why voltage is not enough
Voltage tells you charge, not health
Put a meter across a rested battery and 12.6 volts or a little above means fully charged. Around 12.4 is roughly three quarters, 12.2 is about half, and anything sitting at 12.0 or below has been flat and has probably taken damage from it.
Here is the catch. A battery with one dead cell or plates that have shed most of their material can still show 12.5 volts sitting there doing nothing. Ask it to turn a starter motor and the voltage collapses. That is why cars get jump started, run all day, and refuse to start again the next morning while the owner insists the battery reads fine.
Load testing
Load test
Does what the starter motor does. The tester draws a heavy current, usually about half the battery's rated cold cranking amps, for ten to fifteen seconds while watching what the voltage does. A healthy battery holds up above roughly 9.6 volts at normal ambient temperature. One that dives towards 8 volts is finished, whatever it read at rest.
Conductance testing
Conductance test
Takes a different route to the same answer. It measures the battery's internal resistance and works backwards to an estimated cold cranking amp figure, compared against what is printed on the label. A battery rated at 600 CCA that now tests at 300 has lost half its capacity. Quick, works on a partly flat battery, and does not need the battery warm.
The full test
Why the alternator and starter get tested too
A battery is rarely the whole story. It is the part that shows the symptom, and the parts either side of it are what usually caused the symptom. An alternator that has stopped charging leaves the battery to run the car until it cannot, and the battery gets blamed. An alternator overcharging at 15 volts and up cooks a battery in months. A starter drawing far more current than it should flattens a healthy battery every morning and shortens its life.
So the test we run covers state of charge and battery health, cranking voltage while the engine turns over, starter current draw, charging voltage at idle and with the lights and blower on, and voltage drop across the main cables and earths. That is a few minutes of work and it stops the wrong part being replaced.
Brisbane lifespan
How long batteries last here
Around three to four years is the realistic expectation in South East Queensland. Somewhere cooler the same battery would often reach five or six. Heat accelerates the corrosion of the internal plates and drives fluid loss, and neither of those is reversible. Once your battery is past its third summer here, test it before it strands you.
Warning signs
Signs you should get it tested now
- Cranking sounds slower or heavier than a few months ago
- The car is fine after a run but reluctant first thing in the morning
- Headlights visibly dim while cranking
- You have needed a jump start even once
- Stop-start has quietly stopped working
- The battery is over three years old
Common questions
Frequently asked questions
How much does a battery test cost?
[CONFIRM: whether battery testing is free or a set price] It is a short job and we would rather test it than have you towed.
Is 12.4 volts a good reading?
It means about three quarters charged. It says nothing about whether the battery can still deliver current, which is what a load or conductance test is for.
My battery reads 12.6 volts but the car will not start. How?
Because voltage under no load is not capacity. A failed cell can read normally at rest and collapse the moment the starter draws current.
How long do car batteries last?
In Brisbane, generally three to four years. Heat shortens battery life more than cold does.
Can a battery be recharged instead of replaced?
Sometimes. A good battery flattened by a light left on will recover on a proper charger. One that has been deeply flat repeatedly, or that fails a load test, will not.
Do I need to leave the car with you?
No. Testing takes minutes, though booking means you are not waiting behind other jobs.
Can you test the battery at my place?
Yes. Battery testing is one of the jobs our mobile service handles across Brisbane, Logan, Ipswich, Moreton Bay and Redlands.
Will you test the alternator at the same time?
Yes, and the starter draw with it. Testing the battery alone answers only part of the question.
Does stop-start use a different battery?
Yes. Stop-start cars use AGM or enhanced flooded batteries, and they need testing on the right setting to give a true result.
My car is a hybrid. Does this apply?
The 12 volt battery in a hybrid or EV is tested the same way and fails the same way. The traction battery is a separate matter entirely.
Book a battery test
Test the whole system.
Replace only what failed.
Monday to Friday 8am to 5pm, Saturday 8am to 3pm. Mobile service available. All major cards and cash.