AGM and EFB Battery Fitments Explained

If you have a Start-Stop engine, you need a Start-Stop battery. These batteries have been developed specifically for Start-Stop engines and can quickly recover power lost as a result of starting the engine. On many modern cars, the battery isn’t where you think it might be; other than in the engine bay, the battery can be found in the boot, under the passenger seat or under flooring. It can take up to two hours to change the battery on some vehicles! Even if the battery is in the traditional area, it can take a long time to fit a replacement battery; the battery box may be under another part or tucked behind a difficult to remove piece of equipment. 

Absorbed Glass Mat (AGM) and Enhanced Flooded Batteries (EFB) have increased cyclic ability compared with a conventional battery and require a specific testing and fitting procedure. AGM and EFB batteries are monitored by an Intelligent Battery Sensor (IBS) which communicates the battery’s voltage, starting capacity and charging needs to the alternator. When an AGM or EFB battery is replaced the IBS needs to be told a new battery has been fitted, this is called battery validation. If the new battery isn’t validated it could fail prematurely, the Start-Stop function could be affected, and dashboard warning lights could come on. 

It's important to note that if you have a Start-Stop AGM or EFB battery already fitted in your car, you must replace it like for like. Using a conventional battery in place of an AGM or EFB battery could cause serious and costly issues. 

 All our technicians are trained to test and fit all batteries, including Start-Stop AGM and EFB batteries. 

Still Need Help? - Find your Car New Battery here:

All batteries can be purchased at your local Protyre. With same day fitting available. 

Find My Protyre

About the author

David Sholicar

David is the National Retail Operations Manager for Protyre. One of David’s areas of responsibility and ...

View author

Related Articles


The winter months put additional strain on batteries and ensuring they are in good working order and that they are charging correctly will ensure that those early morning or late night breakdowns become far rarer industry sources suggest that one of the principal reasons for breakdown call outs is a faulty battery.
Find out more

How To Change Your Battery

Changing your car battery is one of the most important elements of vehicle maintenance. Your battery can run flat for a number of reasons including the age of the battery or car itself, accidently leaving headlights on or there could possibly be a fault.
Find out more

How To Charge Your Car Battery

Charging your car battery is an important aspect of vehicle maintenance. Your battery’s power can run low for of a number of reasons including age, a fault or leaving the headlights or other electrical features of the car on for a prolonged period. If you don’t feel up to disconnecting and charging the battery yourself then consult an expert.
Find out more