Standard lead-acid vs AGM: What’s the right battery for a Start/Stop vehicle?

All motorists know how important the battery is for their vehicle, but when it comes to needing a replacement battery, few people know which is the best battery for their cars.

“Most motorists only pay attention to the battery when it starts giving trouble," said Jason Ravenscroft, Franchise Manager at Battery Centre, a network of more than 120 battery fitment centres around Southern Africa. Ravenscroft explains that the right battery should meet the demands of the vehicle, specifically newer vehicles, where there is a continuous discharge and charging process of the battery.

Many new vehicles with Start/Stop technology use batteries specially manufactured with Absorbed Glass Mat (AGM). Start/Stop cars switch off several times during a single drive, such as waiting for a traffic light to change, and when the brake is released, or the accelerator is engaged, the car starts hassle-free because of the battery.

The difference between standard flooded lead-acid and AGM batteries 1, 2, 3, 4

AGM batteries are a newer technology lead-acid battery which loses almost no water and is powerful enough to start the engine and keep things running when the car is switched off. They require no maintenance, which is why they can be positioned in the boot or under the seat. The electricity produced when braking is stored in the AGM battery.

Can you use a standard lead-acid battery in a Start/Stop car? 4

“It’s strongly not advised,” Ravenscroft urged. “It can void the car and battery warranties.” A standard lead-acid battery cannot endure the demands that a battery is subjected to in a high end Start/Stop application and will fail prematurely. In addition to this, where the vehicle utilizes regenerative braking technology, a standard lead-acid battery will not be able to accept the rate of charge through this process and could lead to the unit swelling up, leaking acid into the vehicle through excessive heat build-up or, in the worst case, explode within the vehicle.

Battery Centre offers two options depending on the requirements of each vehicle fitted with Start/Stop technology. Entry levels systems would require the fitment of an Enhanced Flooded Battery (EFB), whereas the more sophisticated systems will require an AGM battery to be fitted.