Exide Develops More-Robust Battery to Meet Stop/Start Demand

In an automotive world soon to be populated with fuel-saving start/stop systems, the duties of a traditional light-vehicle battery will become more rigorous and require further innovations to keep pace with the extra power demand.

So says Paul Cheeseman, vice president-global engineering and research, at battery maker Exide Technologies.

“Your battery will no longer be starting your car once or twice per day. With stop/start systems, it will go from performing about 5,000 starts in its lifetime to 50,000 starts,” he tells WardsAuto in an interview. “It will start your car many more times a day, so (the technology) has to be different.”

Milton, GA-based Exide answered the call for a new battery technology in 2008, when the European Union passed tighter carbon-dioxide emissions mandates on passenger vehicles now hitting the market.

About 60% of the new cars sold in the region use the technology to keep auto makers in compliance with the 130 g/km CO2 standard. The rules will drop to 95 g/km by 2020.

In the U.S., where the march to a 2016 corporate average fuel economy of 35.5 mpg (6.6 L/100 km) kicked in last year, stop/start systems are just beginning to appear. However, experts think their penetration will reach 50% within five years from less than 5% today.

Some industry insiders think every car will employ stop/start within 10 years, as U.S. fuel-economy rules climb to an expected 54.5 mpg (4.3 L/100 km) in 2025.

Fuel savings from current stop/start technologies range between 5% and 8%, depending on the driving cycle and vehicle class. The technology adds about $300 to the cost of a new vehicle.

Next-generation stop/start systems might demand even more from a vehicle’s battery, evidenced by technologies recently demonstrated by German suppliers Hella and Bosch that shut down an engine whenever torque is not needed. Today’s systems shut down the engine only at idle, restarting when the driver engages the clutch or releases the brake.

Beyond stop/start systems, the sophisticated electronics of future vehicles for next-generation creature comforts and enhanced connectivity also will demand extra power from the battery.

Exide’s solution, called Advanced Glass Mat, leverages a 30-year-old technology and uses as its basis the same lead-acid chemistry dating back 153 years. AGM batteries have been employed for a number of years in industrial applications, such as backup power for cellular-telephone towers.

But unlike a traditional flooded lead-acid battery that employs a thin separator of polyethylene material between its positive and negative sides, Exide Edge AGM batteries use an absorbent glass mat as a separator.

The AGM separator acts like a sponge and pushes against the positive and negative sides of the battery. The pressure prevents wear and tear on the battery’s lead plates, a process known as shedding, and contributes to the battery’s longer life, Exide says.

The traditional flooded lead-acid battery also allows gases to escape the unit. The spongy separator inside an AGM battery keeps those gases contained inside the battery housing, remaking acid. The result is a completely sealed battery that is maintenance free. Exide’s AGM technology employs graphite, which helps recharge the battery more quickly.

In a stop/start situation, for example, it takes about one minute of driving to recharge a traditional flooded lead-acid battery with the power used by the vehicle’s accessories while the engine was shut down and the energy needed to restart it.

As the battery ages, the recharge time takes longer, up to 10 minutes after just one year of duty, Exide says. Graphite helps the battery stay like new longer.

Exide AGM batteries are more expensive, costing nearly twice as much as a traditional flooded lead-acid battery. But they last longer, between three and six years in a vehicle with stop/start compared with as little as six months with the lead-acid battery in the same car or truck.

“Lead-acid batteries are the Achilles’ heel of stop/start systems,” Cheeseman says, while hesitating to give a bullish prediction for AGM sales based on the future proliferation of stop/start systems in the U.S.

In fact, he thinks estimates using Europe as a basis for stop/start popularity in the U.S. are inaccurate because future emissions standards between the two are not the same.

It remains unclear how strict the penalty might be in the U.S. when an auto maker fails to meet future requirements, he adds, whereas in Europe it will result in fines in the thousands of euros.

So Exide is hedging its bet with AGM by recently introducing the technology to additional markets such as the marine industry, where the draw on battery power also is high. Additionally, the company also has an AGM battery for auxiliary power uses, such as for campers.

Exide also operates three facilities in Europe making the AGM batteries.

Exide’s launch of AGM battery technology in the U.S. has borne other fruit. The supplier received several U.S. government loans handed out three years ago to stimulate production of fuel-efficient vehicles. That $30 million was sunk into manufacturing facilities for AGM batteries in Columbus, GA, and Bristol, TN.

“We’re making these batteries, and we’re creating jobs. We feel pretty good,” Cheeseman says.

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