Battery fitting
AGM battery replacement
If the car was built with an AGM battery, the replacement is another AGM. We won't fit a weaker battery to save a step. We'll come to the car in London, Birmingham or Manchester, and register it where the car needs that.
Is this postcode in the fitting area?
What an AGM battery is doing on the car
AGM means absorbed glass mat. The acid is held in the mat, the case is sealed, and the battery is built to be cycled harder than a plain flooded unit. You will find them on many stop-start cars, on cars that recover energy as they slow, and often where the battery sits in the boot or under a seat.
The label usually says AGM, or the car data does. If the old battery is AGM, the new one is AGM. That is not a preference. An AGM must not be downgraded to EFB or to flooded. A flooded battery is the wrong part, and it will not be fitted.
Replacement at the vehicle
The fitter comes to the parked car, confirms the label, and checks the case. A healthy 12V battery rests around 12.6V. An AGM that has been deeply cycled may sit lower and still be the correct technology to replace like for like. Swelling, cracks, leaks or a frozen case mean no jump leads.
Running charging voltage is often about 13.8 to 14.7V while the battery is accepting charge. Smart charging can sit lower once the battery is reported full. If the car still thinks the old AGM is fitted, that profile can be wrong for the new one. Registration, where the model needs it, is part of the job, not an extra you discover later.
Registration and where the battery sits
Battery registration is commonly required on Volkswagen Group and many BMW and Mini models, and it varies on other marques. Plenty of those cars use AGM. The scan tool is told the new battery type and capacity so the charging strategy starts again from a new unit.
Boot-floor and under-seat AGM packs take longer to reach than an open engine bay. Trim, a seat base or a spare-wheel panel has to come up cleanly and go back. Say where the battery is on the quote form. The alternator is not a bulk charger, so we do not leave a new AGM to be sorted out by a short drive.
AGM against EFB and flooded
An EFB is a reinforced flooded battery used on many entry stop-start cars. It may be replaced with another EFB or upgraded to AGM. The traffic does not run the other way: an AGM car does not step down to EFB. A non-stop-start car on a plain flooded battery stays on flooded unless the vehicle data says otherwise.
Tell us the registration and that the battery is AGM, and type your mobile number. We call you back to confirm the unit and whether registration is required. Cover is London, Birmingham and Manchester, at the vehicle. There is no depot and no printed price.
| Point | Flooded | EFB | AGM |
|---|---|---|---|
| Construction | Liquid electrolyte | Reinforced flooded plates for cycling | Acid held in a glass mat, sealed case |
| Typical use | Cars without stop-start | Entry stop-start | Heavier stop-start, boot or under-seat packs |
| Replacement rule | Like for like on a simple car | Replace with EFB or upgrade to AGM | Replace with AGM only |
| If it is downgraded | Wrong if the car was EFB or AGM | Wrong if the car was AGM | Must not be downgraded |
Questions before you send a quote
Can you fit an EFB instead of an AGM?
No. An AGM battery is replaced with AGM. It must not be downgraded.
Can an EFB car take an AGM?
Often yes, as an upgrade, when the car and the registration step allow it. The callback confirms that car.
Do AGM cars need battery registration?
Many do, especially Volkswagen Group and a lot of BMW and Mini models. Other marques vary. It is confirmed per car.
How do I get a quote?
Use the quote form and type your mobile number. We call you back. The fitter then comes to the car in London, Birmingham or Manchester.