AGM & EFB batteries
AGM and EFB battery replacement for start-stop cars
If your car switches its engine off at the lights, it needs an AGM or EFB battery — usually the type it left the factory with — and many European cars also need the new battery registered with the car's battery management system. We bring the right battery to wherever the car is parked, fit it, and register it on site with a diagnostic scan tool.
Which cars need AGM or EFB
- Any car with start-stop, whatever the make. The battery restarts the engine dozens of times a trip, which a flooded battery isn't built for.
- Most recent BMW, Mercedes-Benz, Audi, Volkswagen, Porsche and Range Rover models, which usually leave the factory with AGM.
- Japanese and Korean start-stop models — many Toyota, Mazda, Nissan, Hyundai and Kia versions with idle-stop use EFB or AGM.
- Cars with heavy electrical loads — large infotainment systems, heated or cooled seats, dashcams and trackers running while parked.
The quickest check is the label on the battery you have now: it will say AGM, EFB or neither. If the label is gone, tell us the make, model and year and we confirm it before the van leaves. Our guide to AGM vs EFB vs flooded batteries explains the difference in detail.
Why a cheaper flooded battery is a false saving
A flooded battery fitted to a start-stop car usually fails within about a year. Before it does, the car often disables start-stop, shows battery or charging warnings, and runs the alternator harder trying to recharge a battery that can't keep up. You pay for two batteries in the time one AGM would have lasted.
| Flooded | EFB | AGM | |
|---|---|---|---|
| Built for | Cars without start-stop | Entry-level start-stop | Full start-stop, brake energy recovery, heavy electrical load |
| Restarts per trip | Few | Many | Many, plus deep discharge |
| Relative price | Lowest | Middle | Highest |
| Can replace | Flooded only | EFB or flooded (non start-stop) | AGM only — never downgrade |
Registration and coding, on site
Many European cars track the age and capacity of their battery and adjust how hard they charge it. Fit a new battery without telling the car, and it keeps charging the new one as if it were the worn-out old one — overcharging it, shortening its life and sometimes switching start-stop off. Registering the battery with a scan tool resets that strategy. It takes a few minutes and is part of the fitting, not an extra visit.
If you change the battery's capacity or type — say from 80Ah to 90Ah, or EFB to AGM — the car may also need coding to the new specification. See battery registration after replacement for which makes need it.
AGM and EFB brands on the van
Varta and Bosch are the original fit on many European cars and carry a 24-month warranty. Mobis is the genuine part for Hyundai and Kia start-stop models, and Autopart offers AGM at a lower price tier. Compare them all on the battery brands page.
Heat and AGM batteries
No battery chemistry is immune to Gulf heat. Under-bonnet temperatures near 70°C in summer speed up the corrosion that wears every battery out, AGM included, and a battery here typically lasts 18–30 months. AGM's sealed construction means it loses no water, which helps, but it is not a reason to skip a load test before summer.
What it costs
AGM and EFB batteries sit above flooded batteries in price, and the exact figure depends on the size your car takes and the brand. We confirm the price on the phone or WhatsApp before we come. It includes the battery, delivery, fitting, registration where the car needs it, a load test of the charging system, old-battery disposal and VAT.
Questions
Can I replace an AGM battery with a normal one?
No. A flooded battery in a car designed for AGM usually fails within about a year and can disable start-stop. Replace AGM with AGM.
Can I upgrade from EFB to AGM?
Usually yes, and it can make sense in heavy-use cars, but some cars need coding to the new type. We check before fitting.
Do you register the new battery?
Yes, on site with a diagnostic scan tool, for makes that need it — including BMW, Mercedes-Benz, Audi, Volkswagen and Range Rover.
How do I know if my car has start-stop?
Look for an "A" button with a circular arrow near the gear lever or on the dashboard, or check whether the engine switches off when you stop at lights.