If your car shuts off automatically at traffic lights and restarts the moment you lift your foot from the brake or press the clutch, you have a stop start system. To make that type of system work reliably, your vehicle needs a specific type of battery built to handle it.
Standard car batteries are designed to start the engine once per journey. Stop start vehicles can restart the engine dozens or even hundreds of times on a single urban drive. A conventional battery simply cannot cope with that kind of demand, which is why dedicated stop start batteries exist.
In this post, the Filter Services UK team will explain what stop start batteries are, including the most common types available.
How Does a Stop Start Battery Work?
A stop start battery does three things that a standard battery cannot do well:
- It powers the vehicle’s electrical systems while the engine is switched off
- Restarts the engine rapidly when you pull away
- Recharges quickly during the short periods the engine is running.
To achieve this, stop start batteries are built with greater cyclic durability than standard lead acid batteries. Cyclic durability refers to how many times a battery can discharge and recharge before its performance begins to degrade. In a stop start vehicle, that cycle happens far more frequently than in a conventional car, so the battery needs to be rated for it.
There are two main types of stop start battery: EFB and AGM.
EFB Batteries (Enhanced Flooded Battery)
EFB stands for Enhanced Flooded Battery. It is a development of the traditional lead acid battery, featuring thicker plates, improved separators and better electrolyte circulation. These improvements give it significantly better cyclic durability than a standard battery.
An EFB battery can handle approximately 270,000 engine starts, compared to around 30,000 from a standard flooded battery. EFB batteries are typically found in smaller to mid-size vehicles with simpler stop start systems and lower electrical demands. They offer a cost-effective solution for entry-level stop start applications.
If your vehicle came fitted with an EFB battery, you can replace it with another EFB or upgrade to an AGM. You should not downgrade to a standard flooded battery.
AGM Batteries (Absorbent Glass Mat)
AGM stands for Absorbent Glass Mat. Instead of free-flowing liquid electrolyte, the acid is absorbed into a fibreglass mat inside the battery. This makes AGM batteries maintenance-free and leak-proof.
AGM batteries are the premium option for stop start systems. They can handle as many as 360,000 engine starts and typically last between five and eight years. They are found in higher specification vehicles with greater electrical demands, including those with heated seats, advanced infotainment, air conditioning and regenerative braking systems.
If your vehicle came factory-fitted with an AGM battery, you must replace it with another AGM. Fitting a standard or EFB battery in its place will immediately disable the stop start function and can cause premature battery failure.
GM vs EFB: Which Do You Need?
The choice between AGM and EFB is largely determined by your vehicle rather than personal preference.
Check your existing battery label first. If it says AGM, you need AGM. If it says EFB, you can replace like for like or upgrade to AGM. Both AGM and EFB batteries are monitored by an Intelligent Battery Sensor (IBS) that communicates the battery’s voltage, starting capacity and charging needs to the vehicle’s management system. When you fit a replacement, the system needs to be told a new battery has been installed. This process is called battery registration or validation. Skipping it can cause the stop start system to malfunction or dashboard warning lights to appear.
As a general rule, smaller and mid-range petrol vehicles typically use EFB, while larger vehicles, diesel engines and cars with extensive electrical equipment are more likely to require AGM.
How Stop Start Batteries Affect Your Vehicle Filters
At Filter Services, our core expertise is vehicle filtration, so it is worth understanding how stop start systems interact with your filters over time. If you drive a stop start vehicle, staying on top of filter replacements is just as important as fitting the correct battery.
Oil filters: Each engine restart moves oil through the system under pressure. Frequent pressure cycles can place additional demand on the oil filter. Poor quality oil or a clogged filter in a stop start vehicle can accelerate engine wear, which is why manufacturers often specify higher-grade oils and filters for these cars.
Air filters: Urban stop start driving exposes the air filter to repeated short bursts of intake air mixed with dust and soot. Over time this can cause the air filter to clog faster compared to steady motorway driving.
Fuel filters: More frequent restarts mean the fuel pump primes more often. A partially blocked fuel filter can cause harder starting and place additional strain on the pump. Keeping the fuel filter clean is particularly important in stop start vehicles.
Cabin filters: When the engine shuts off in stop start mode, the climate control blower can continue to draw air through the cabin filter from the battery. This means the cabin filter sees more use than it would in a conventional vehicle.
Have A Stop Start Battery? Ensure Your Vehicle Filters Are Up To Scratch
If your personal or company vehicles have stop start batteries, then it’s key to understand how this different technology can impact other areas within the vehicle.
Filters play an important role in maintaining the health of your vehicle, especially if you have a stop start battery. So if it’s time to replace any of your filters, you’re in exactly the right place!
Simply head over to our filters page to view our available stock.
Filter Services is based in Chesterfield with additional locations in Leeds and Leicester.
For any help or enquiries, please send us a message or give us a call on 01246 802 822.