February 27, 2020: An independent study of enhanced flooded batteries commissioned by lead acid battery giant Exide Technologies has revealed findings that could change the face of the start-stop battery industry in the US, the Atlanta-based battery firm announced on February 25.
The results revealed that EFB technology surpassed AGM batteries in major areas, including battery life, heat tolerance and mid-depth cycling resilience, challenging conventional wisdom about the two technologies, which has long been that AGM batteries were the go-to technology for start-stop applications.
Speaking to BESB on February 26, Alex Templeton, director of marketing, transportation, and John Miller, senior director, product engineering, said they were surprised at how well the technology performed in the tests.
“In a way we all went into it knowing that the EFB was a capable product because it does have a track record in Europe,” said Templeton.
“But when we saw some of the places and weaknesses where EFB was outperforming AGM I think we were surprised.”
The study, by the unnamed third party, looked specifically at Exide’s Marathon range of EFBs, and found that they exceeded AGM performance in battery life, heat tolerance and mid-depth cycling resilience.
Exide the findings would be likely to be repeated across all EFB technology.
EFBs are not new to the industry, of course, and in fact Exide claims it was they who invented the technology and introduced it to the European market in 2008.
However it has never really taken off in the US for various reasons, says Templeton.
“It goes back to how AGM batteries landed in the US, originally through the enthusiast market — die-hard enthusiasts got turned onto the technology and it’s a long-standing belief here that it’s the only battery that should be used in start-stop vehicles — consequently 99.9% of start-stop in the US market is fitted with AGM,” Templeton says.
“It’s completely different from the dynamic in Europe, which is about 50-50 for start-stop, AGM versus EFB. Maybe even more. There it was all AGM but over the years EFB performance grew, and as OEMs in the US are always behind Europe — by about 10 years — we expect it to change here too.”
Batteries have had to change because of changing needs, for example the declining CCA requirement, which traditionally was how a battery was rated.
“There was a time when engine size increased year by year and so need bigger batteries — the larger displacement an engine had, the larger CCA you needed to get it moving,” says Templeton.
“As fuel economy standards have changed, OEMs have pursued smaller engine displacement and used superchargers and the like to get more output out of less displacement, with less lead having to be turned over with the battery.
“But all the add-ons in vehicles now mean that the battery capacity is used over time, and this is more important than the CCA rating. Twenty years ago the battery was only necessary to start the vehicle; once the engine was running the alternator powered it.”
The longer life offered by EFBs is a strong selling point because battery lifespan has actually decreased in recent years, says Templeton. “This research could be a game-changer for EFBs in the US,” he says.
“The key thing in the US market is when you look at average life. In the US, battery returns through retailers are monitored every five years, for the reasons why they went out of service and so on.
“Between 1965 and 2010, the average life span increased every year. It continued to improve.
“Then for the first time between 2010 and 2015 it started declining. Roughly 50% of the batteries have been going out of service because of grid failure — but in the past five years we’ve been seeing a 30% increase in failure with cycling, and it’s because of the inclusion of all these additional electronic features.”
Another finding of the study was how much better EFBs appeared to fare in high temperatures.
“We definitely see a difference in lifespan in warmer climates,” says Templeton.
While Exide maintains that where a vehicle’s battery should be replaced with like for like, ie if it began with an AGM battery, that should be replaced with an AGM battery, and likewise for EFBs, the new battery management systems becoming available would soon be able to probe the batteries much further and possibly identify better alternatives.
“The main concern of a BMS is that it is closely tuned to the battery it’s fitted with, but we’re learning that the BMSs have progressed and have a learning sequence now that can probe the battery, understand it better and go from there,” says Miller.
The message from Exide is that instead of relying solely on one-dimensional CCA ratings to measure a battery’s performance, the market should focus on what’s really important today: the battery’s ability to last longer, stand up to high under-hood temperatures and to durably cycle through its depth of discharge.
So what about cost?
“Without giving away too much, there is definitely a cost incentive with EFB versus AGM, and this to some extent is why you’ve seen the growth in Europe of EFB in the start-stop market,” says Templeton.
“All the materials aside, the process for initially forming an AGM battery is considerably longer than forming an EFB.”