Almost every car sold in Australia since around 2015 has some form of Stop-Start technology — the system that shuts the engine off at the lights to save fuel. It's a clever bit of engineering, but it's brutally hard on car batteries. Fit the wrong one and you'll be back on the side of the road inside 12 months.
What Stop-Start actually demands from the battery
A regular car starts maybe 4-6 times a day. A Stop-Start car can restart its engine 30, 50, even 100 times in a single trip through Perth peak hour. Every restart pulls a massive burst of current (300-800 amps) from the battery. Between restarts, the battery also runs the climate control, lights, infotainment, and engine management — all with the alternator switched off.
Standard flooded batteries (the kind in cars from the 90s and 2000s) can handle about 30,000 charge cycles before failing. A Stop-Start car will burn through that in 6-9 months. The battery doesn't just die — it loses capacity gradually, the Stop-Start system disables itself to protect what's left, and the dash starts throwing warning lights.
EFB vs AGM — the two valid choices
EFB (Enhanced Flooded Battery)
Think of it as a heavy-duty version of a normal battery. Thicker plates, a polyester scrim wrap to stop the active material falling off the plates during heavy cycling, and improved grid design. Handles around 85,000 cycles. Cheaper than AGM, and the right choice for most mid-range cars with basic Stop-Start (Mazda CX-5, Toyota Corolla, Hyundai i30, etc.).
AGM (Absorbed Glass Mat)
The electrolyte is held in a fibreglass mat rather than sloshing around as liquid. Sealed, spill-proof, vibration-resistant, and rated to around 360,000 cycles. Required for cars with regenerative braking (which dumps charge back into the battery in big bursts) and most European cars with stop-start plus heavy electronics — BMW, Mercedes, Audi, Volvo, late-model VW.
Critical: never downgrade
If your car came from the factory with AGM, you must fit AGM again. Downgrading to EFB will cause the battery to fail in 6-12 months and can confuse the car's battery monitoring system, leading to drive-system warnings.
How to tell what's in your car now
- 1Open the bonnet and look at the battery label. AGM batteries are always labelled 'AGM' clearly on the case. EFB is usually marked too.
- 2Check the owner's manual — most have a 'battery specifications' page that lists the required type.
- 3Look for a Stop-Start button or icon on the dash. If you have it, you need at least EFB.
- 4If in doubt, take a photo of your existing battery label and send it to us — we'll spec the right replacement for free.
Common Perth cars and what they need
| Vehicle | Required battery type | Common size |
|---|---|---|
| Mazda CX-5 (2017+) | EFB | Q85 / Q-85 |
| Toyota RAV4 Hybrid | AGM (auxiliary) | S46B24R |
| Hyundai Tucson (2016+) | EFB | DIN65 EFB |
| BMW 3 Series (2012+) | AGM | LN3 / H7 AGM |
| Mercedes C-Class (2014+) | AGM | LN5 / H8 AGM |
| Toyota Hilux (post-2015 diesel) | EFB / Heavy duty flooded | N70ZZ / N70ZZL |
| Volkswagen Golf (2013+) | AGM | LN3 AGM |
| Ford Ranger (2015+) | Heavy duty flooded | N70ZZ |
Don't see your car? We carry every common Perth fitment on the van — call us with your rego and we'll have the right one with us.
What it costs to get it wrong
A few customers a month find us after a major chain has fitted a standard flooded battery to their Stop-Start car. The battery typically fails inside 8-12 months. The original chain refuses warranty because the wrong battery was fitted in the first place, so the customer pays twice — once for the cheap battery, once for the correct EFB/AGM. The total bill is always higher than just doing it right the first time.
Need help speccing yours?
Tell us your rego and we'll tell you exactly which battery your car needs, the warranty, and the on-site price — no callout fee, no obligation. We'll fit it on the spot anywhere in Perth, 24/7.
Frequently asked
Can I just keep fitting standard batteries and disable Stop-Start?+
You can disable Stop-Start (it usually has a button), but the alternator and battery management system are still tuned for a Stop-Start battery. Standard batteries will still fail prematurely and you may get dash warnings.
Is AGM always better than EFB?+
Not necessarily — AGM is overkill (and more expensive) for cars designed for EFB. Stick with what the manufacturer specified.
Why does my Stop-Start sometimes not engage?+
The system needs the battery state-of-charge above ~80%, cabin at temperature, and engine warm. If your battery is weak, the car protects itself by disabling Stop-Start. That's usually the first sign the battery is on its way out.
Do you carry EFB and AGM on the van?+
Yes, every common size for Perth cars. We have Q85, DIN65, DIN75, DIN88, LN3, LN5, S46B24R and more in stock on every callout.
Common service areas for this guide