What Are EFB Batteries? (And When to Use Them)

November 08, 2023

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Conventional flood lead-acid batteries (FLA) have been the standard in the automotive industry for years. They remain a convenient and affordable choice to start the car and power most standard electronics on board. 

But most of today’s cars are far from standard. According to Stryten Energy, the number of electrical devices in modern vehicles has increased 500% in the past 20 years. Car manufacturers are amping up the electronics, including everything from heated seats and onboard entertainment systems to start-stop technology and parking assist. 

More power needs may need a more powerful battery. Enter the enhanced flooded battery or EFB. 

What Is an EFB Battery?

As the name implies, an EFB is an enhanced version of the conventional FLA. 

In both conventional FLA batteries and EFBs, a liquid sulfuric acid electrolyte creates electricity when it comes into contact with the lead plates. Although it’s still a wet cell battery, EFB is sealed and uses a polyfleece material to line the lead plates inside the battery. This offers additional protection for the lead plates and a more consistent energy flow than traditional batteries. 

EFBs also have carbon additives in the lead plates and a specially designed grid structure that transfers electrons more effectively. All these features make EFBs durable and reliable.

Best Uses for EFBs

When compared to conventional FLA batteries, EFBs perform better for high-demand applications where frequent stop-start cycles, deeper discharges and rapid recharging are needed.

Stop-start systems. One of the primary uses of EFBs is in the increasingly popular start-stop systems found in newer vehicles. The start-stop technology automatically shuts down and restarts the engine to reduce the amount of time the car sits idling. A conventional FLA would wear out quickly if required to constantly restart the engine, especially in high-traffic areas, where idling is the norm. EFBs are designed to handle these stop-start cycles without compromising battery life. 

Regenerative braking. Many electric and hybrid vehicles take advantage of regenerative braking to convert the energy usually lost during braking into electricity. The electricity is fed back into the battery. EFBs are built to handle the quick charge and discharge cycles brought on by regenerative braking. 

Warmer climates. The typical FLA lasts about 58 months in northern climates, but as you head south, where temperatures are hotter year-round, that number drops to as low as 41 months. EFB batteries have a higher heat tolerance, making them longer lasting than FLAs; they even tolerate high temps better than AGMs.  


Sealed No Yes
Lifespan 3-5 years Up to 6 years
Approximate engine starts 30,000 85,000
Cycle Life 250-500 cycles 500-1000 cycles
Duty Cycle 50% DOD 60% DOD
Best for Traditional engine starts, basic accessory loads Small- to mid-range systems with stop-start technology, hybrid systems



EFBs were designed as a middle ground between standard batteries (which cannot handle the energy demand many modern vehicles have) and absorbed glass mat (AGM) batteries, which are powerful but can be expensive. 

Compared to AGMs, EFBs have a lower cost upfront and a longer cycle life. EFBs also outperform AGMs in temperature tests, making them ideally suited for warmer climates. On the other hand, AGMs offer more electrical energy and can recharge up to five times faster



Sealed Yes Yes
Lifespan Up to 6 years 5-8 years
Approximate engine starts 85,000 60,000
Cycle Life 500-1000 cycles 400-600 cycles
Duty Cycle 60% DOD 80% DOD
Best for Small- to mid-range systems with stop-start technology, hybrid systems High-powered vehicles like electric cars and trucks


When to Choose an EFB

First, look at the type of battery factory-installed in your vehicle. Many cars still come with a conventional FLA battery, but manufacturer-installed AGMs and EFBs are becoming more common. 

An EFB may be a suitable upgrade for a standard FLA. However, swapping out EFB or AGM batteries for a conventional FLA is not advisable. Before replacing your battery: 

  • Consult your owner’s manual and a battery specialist. 
  • Consider your vehicle’s electric demand. If you have a start-stop system or other advanced electronics, an EFB may be better suited to your needs. 
  • Check size, capacity and CCA. The size and terminal configuration should match your original battery. The capacity and cold cranking amps (CCA) should match or exceed the original battery. 

The Future of EFB

EFB adoption is steadily growing in the United States, but the batteries have been used widely in Europe since 2008. Today, about half of European cars come standard with EFB batteries, but EFB is set to overtake AGM (which held market share previously) in the near future. 

As U.S. manufacturers continue to integrate more technology into vehicles that make them safer and more comfortable, the more energy they will need. Over the next five years, the stop-start battery market, which includes EFBs, is expected to see a growth rate of about 19%

Clearly, EFBs are more than a passing fab. They are carving a significant niche in the automotive industry and beyond. The emergence of EFBs represents a move towards smarter, more resilient automotive solutions and a reliable and efficient future for drivers. 

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