Guide to AGM & EFB Automotive Batteries

🔋 Your Guide to AGM & EFB Automotive Batteries

Choosing the right battery for your car, especially a modern one with Stop-Start technology, can be tricky. This guide breaks down two of the leading advanced battery types: AGM (Absorbent Glass Mat) and EFB (Enhanced Flooded Battery).

AGM Batteries Explained

AGM technology is a major leap forward from traditional car batteries. It uses a special fibreglass mat to absorb the electrolyte (acid), which offers superior performance, especially in high-demand vehicles.

Key Features & Benefits

• Superior Power: Delivers higher cold-start performance (essential for reliable starting in cold weather).

• Enhanced Durability: Increased lifespan due to the clever design that minimises the shedding of active material.

• Zero Maintenance: They are completely sealed and maintenance-free—you never need to top up the water.

• Safer Design: Spill and leak-proof for safer handling and installation.

• Built for Modern Cars: Designed to meet the stringent demands of the latest Original Equipment Manufacturers (OEM), including vehicles with sensitive onboard electronics.

• The Go-To for Luxury & Stop-Start: AGM is now factory-fitted in many premium cars and high-spec Stop-Start vehicles that require the best power solution.

Yuasa's AGM Expertise

Yuasa brings its world-leading AGM technology—proven in their motorcycle and industrial batteries for decades—to the automotive market. This experience, refined in vehicles like the Mazda MX5 and Toyota Prius, has been engineered to handle the extreme power demands of modern European vehicles.

Our new European-sized AGM batteries (like the popular 096 and 019) offer reliable starting while coping with the intense power needs of today's cars. Lab tests show they offer 4-5 times the cyclic durability of a standard flooded battery and typically 16% higher starting power, even in the cold. This efficiency is down to the increased reaction surface area, which ensures faster engine rotation during starting and helps maximise your fuel economy.

How AGM Works (The Tech Bit)

The "Absorbent Glass Mat" separator fully absorbs all the battery acid. This gives the battery a number of key advantages:

• Gas Recombination: During normal operation, gases produced when charging are recombined back into water. This is what makes the battery totally maintenance-free.

• Leak-Proof & Safe: A one-way venting system provides internal pressure, making them 100% leak-proof and safe to handle.

• Increased Durability: The absorption of the acid allows the battery to operate under higher pressure, which significantly prolongs its cycle life by preventing the active material from shedding.

• Vibration Resistance: The increased internal pressure also makes the AGM battery much more resistant to vibration.

EFB Batteries Explained

Also known as AFB (Advanced Flooded Battery) or ECM (Enhanced-Cycling-Mat), the EFB is a highly improved version of the traditional wet-flooded battery.

Key Features & Benefits

• Built for Entry-Level Stop-Start: EFB technology is the cost-effective solution often factory-fitted in entry-level Stop-Start vehicles.

• Enhanced Charging: Offers significantly faster acceptance of dynamic charge current (up to +170% over standard batteries), thanks to special carbon additives and separators.

• Improved Cycle Life: Provides 100% greater cyclic durability than a standard flooded battery.

• Safer Design: Features a sealed double lid with an integrated flame arrestor.

EFB for the UK Market

The UK's focus on lower EU emissions targets for entry-level vehicles has driven demand for EFB technology. It strikes a balance, offering the cyclic demands of Stop-Start systems but at a lower price point than AGM.

Yuasa's YBX7000 Start Stop range offers 11 new EFB battery types, covering both European (DIN) and Japanese (JIS) sizes to maximise coverage of vehicles across the UK.

Beyond Stop-Start

EFB batteries are also ideal for other demanding scenarios. In applications with repeated deep discharge, like Police vehicles or Taxis, EFB technology provides improved cyclic durability compared to standard premium wet-flooded batteries.

Frequently Asked Questions (FAQs)

Q. Flooded vs. AGM: What’s the main difference?

A. AGM batteries are built using a glass mat separator that holds all the electrolyte (acid). This design allows gasses to recombine into water, making them completely maintenance-free. Critically, the glass mat allows the battery to operate under a higher internal pressure, which gives AGM batteries their significant step-change in durability compared to traditional flooded types.

Q. EFB vs. AGM: Which one should I choose?

A. EFB batteries are an enhanced version of the existing flooded technology, relying on improvements like carbon additives. AGM batteries are a fundamentally different design (glass mat, high pressure, recombination lid). AGM is the higher-tier option and is best suited for demanding vehicles with features like Stop-Start, Regenerative Braking, and Passive Boost. EFB is the lower-tier, cost-effective option for entry-level Stop-Start cars.

Q. Can I store my AGM/EFB battery on the garage floor in winter?

A. Yes, absolutely. This is a common misconception dating back to old batteries with wooden or glass cases. Modern batteries with hard plastic cases are completely fine on a concrete floor, as long as there are no sharp objects to damage the casing. As with any battery, keeping it in a charged state will prevent it from freezing.

Q. Do AGM or EFB batteries have a 'memory'?

A. No. The 'memory effect' is only a characteristic of Nickel Alkaline battery systems, such as Nickel-Cadmium.