AGM aftermarket falters as drivers disable start-stop function

Johnson Controls, the world’s largest start-stop battery manufacturer, told BESB on August 10 that ‘parties’ were discussing the complete removal of the option to override the start-stop function in new cars.

Another global lead battery manufacturer that asked not to be named also said it “does believe there will eventually be a requirement to remove the choice of using start/stop in the vehicle given its use is directly tied to CO2 emissions and fuel economy standards”.

Although there is no legislation that orders OEMs to remove the override function, some carmakers are already making the option more and more obscure, Christian Riedel, director of communications EMEA for JCI, told BESB.

“Until today for most of the cars it’s been possible to switch off the function, which means the battery lasts longer,” said Riedel. “This is nice for the customer, not so for the battery maker.

“But there are changes coming. Already it is not so simple to find the switch. There are some vehicles that used to have a simple button to push to switch off the function. Now you have to look through a menu and scroll down before you can find it.”

Aftermarket growth in AGM and EFB batteries used in start-stop vehicles has failed to meet predictions because the batteries are being under-used by drivers who choose to switch off the start-stop function in their vehicles, said John Bentley, technical spokesman of Ecobat Technologies (formerly Manbat).

“The fundamental issue comes down to the fact that the AGM batteries developed to cope with the demands of these start stop systems are, in practice, not being used in the way they were designed,” he said.

“The AGM battery is a formidable piece of engineering that, unlike a traditional SLI battery, is designed with a high cyclic capacity and the ability to recharge extremely quickly. This is needed because, over their design life, which was projected to be around four years, they are expected to make 350,000 engine starts, compared with the 30,000 expected by an SLI battery in a non start-stop vehicle.

“However, because the average driver is uncomfortable with their vehicle doing its own thing and starting and stopping at will, the vehicle manufacturers have incorporated an override button that has allowed them to deactivate the system, which means the battery is only making the number of starts an SLI battery is designed to make.”

In what could be a step towards legislation, Riedel said parties, including customers he did not name and the German automobile association ADAC, were in talks to get the function added to the list of parts that had to be checked in annual road worthiness tests – so when the start-function was checked, the battery would have to be up to scratch.

But although AGM or EFB batteries are more expensive than standard SLI, the cost of having to replace them more often would be balanced by the fuel savings, said Riedel.

“These batteries result in an average fuel consumption saving of 5%,” he said. “We have our own internal test vehicles and we achieved numbers which are higher than 5%.”