Walk into any battery supplier and you’ll hear three terms thrown around: conventional, EFB and AGM. Fitting the wrong type can cost you battery life — or stop a Start-Stop system working at all. Here’s the plain-English version.
Conventional (flooded) batteries
These are the traditional lead-acid batteries that have powered cars for decades. The electrolyte is a free-flowing liquid, and they suit older vehicles with simple electrical systems and no Start-Stop.
Best for: older runabouts and cars with minimal electronics. In our range: Bosch S3, Energizer and Energizer Plus.
EFB (Enhanced Flooded Battery)
An EFB is an upgraded flooded battery built to handle the extra cycling that Start-Stop driving demands. A polyester scrim on the positive plate stabilises the active material, roughly doubling the number of charge cycles compared with a conventional battery.
Best for: entry-level Start-Stop vehicles. In our range: Energizer Premium EFB.
AGM (Absorbent Glass Mat)
In an AGM battery the electrolyte is held in a glass-fibre mat rather than sloshing around freely. This makes the battery completely spill-proof, highly vibration-resistant, and capable of up to three times the cycle life of a standard battery. AGM is the top tier for demanding modern electrical systems.
Best for: Start-Stop vehicles with regenerative braking and heavy electrical loads. In our range: Energizer Premium AGM and the silver-alloy Bosch S5 for vehicles with ABS, GPS and multiple ECUs.
A quick rule of thumb
| Your car | Battery type |
|---|---|
| Older, simple electrics | Conventional |
| Entry-level Start-Stop | EFB |
| Start-Stop + regen braking | AGM |
The golden rule: you can usually upgrade (fit AGM where EFB is specified) but you should never downgrade. Fitting a conventional battery to a Start-Stop car will dramatically shorten its life.
Still not sure?
Don’t guess. Call Randwick Car Batteries with your make, model and year and we’ll confirm the exact battery your car needs — then fit it while you wait.