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EFB vs. AGM: What Will Power Our Cars in the Future?

Absorbed Glass Mat (AGM) batteries have long been accepted as the preferred option for start-stop vehicles, and as a result, most modern vehicles on the road today are equipped with them. But a newcomer to the market – Enhanced Flooded Batteries (EFB) – is poised to threaten AGM’s place in the United States market. 

Consumers expect certain conveniences in today’s vehicles, including infotainment, voice recognition and anti-theft systems, but those features can be particularly draining on the batteries that must provide power for them to function. So, the right battery choice is critical. 

While AGM batteries have handled the demands created by modern automobiles, new research shows EFB technology actually surpasses AGM offerings in critical areas such as battery life and heat tolerance, to name a few. In addition, EFB technology is more affordable than AGM.

The European Connection

EFB might be new to the United States, but the technology has been used in the European market since 2008. Since the U.S. automotive industry typically follows its European counterparts by approximately ten years, the time for EFB to shine is now.

European automobile manufacturers relied heavily on AGM solutions to power start-stop vehicles until 2008, when a shift began to take place, resulting in what is now an even division between AGM and EFB. At this point, approximately half of all vehicles in Europe use AGM batteries and half use EFB, but EFB is taking the market lead.

Looking Closely at New Research

A study, commissioned by Stryten Energy and conducted by an independent third-party research company and battery testing lab, tested the performance of EFB technology in comparison to AGM batteries and came up with some surprising results. 

In many areas, EFB matched the performance of AGM, which challenges the long-held belief in the United States that AGM is a better option. In addition, EFB outperformed AGM in several other areas including battery life, heat tolerance and mid-depth cycling resilience. 

  • Battery returns in the United States are monitored every five years to determine why batteries go out of service. Between 1965 and 2010, the average battery’s life span increased each year, but between 2010 and 2015, battery life began to decline. Since then, the U.S. market saw a 30 percent increase in battery failure with cycling, which is directly caused by the ever-increasing use of battery-draining electronic features in automobiles.
  • To measure mid-depth cycling resilience, the study performed a 17.5 percent Depth of Discharge Test, which is the industry standard for measuring a battery’s ability to operate under a partial state-of-charge application. This test is not only a simple measurement of a battery’s mid-depth cycling capability, but it is also designed to determine the cycle-to-cycle recharge capability of the battery. Partial state-of-charge operation is common in stop-start applications. Over an 18-week period, the total average capacity output of EFB was 50 percent greater than AGM for an equally sized battery. This finding indicates EFB not only can yield as many cycles as AGM but can also hold its total capacity to a higher level without decay.
  • An area where EFB greatly outperformed AGM was in temperature tests. AGM batteries tend to lack thermal stability, which leads to shorter battery life in high temperatures. As a result, the U.S. Military has incorporated an overcharge/thermal runway test to its AGM test requirement process. The new study showed an EFB battery is able to handle a temperature increase at 50°C and absorb 52 percent more energy than a comparable AGM battery. When translated into an operations environment, the implication is that an EFB will last 52 percent longer than an AGM battery in high-temperature environments.
  • A battery’s ability to accept a recharge after a discharge event is a feature with growing importance in today’s market, as it is a measurement of how prepared the battery will be to support the next discharge cycle. This capability is currently measured by a Dynamic Charge Acceptance test, which determines a battery’s charge acceptance capability under typical states of operation. When replicating real-world start-stop usage, the test showed EFB offers charge acceptance capability that is equal to AGM batteries.

Driving Ahead: Implications for the Future 

Evidence provided by more than a decade of use in Europe as well as the latest U.S. study indicates EFB is just as good as AGM in terms of automotive battery performance. In most cases, EFB is even better than AGM. But if AGM and EFB are so similar, why would the U.S. automotive industry go to the trouble to switch from using AGM to EFB? The answer is simple: superior battery performance. 

While AGM is still the battery of choice for powering deep cycle needs, which is a niche use of automotive batteries, EFB will provide a better experience for the majority of consumers. It may be too soon to tell which technology will win the U.S. automotive battery battle, but one thing is for sure: EFB is truly a game changer.

John Miller, Senior Director of Product Engineering, Stryten Energy

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