What is the difference between flooded, EFB and AGM batteries?
Short answer: Flooded batteries use free liquid electrolyte, EFB batteries are a stronger flooded design for light start-stop duty, and AGM batteries hold the electrolyte in glass mats for better cycling and vibration resistance.
A conventional flooded battery is the traditional design with liquid electrolyte. It works well in vehicles with basic electrical demands but handles repeated deep discharges poorly.
An enhanced flooded battery adds design changes that improve cycling life, and many entry-level start-stop vehicles use it. An absorbed glass mat battery holds the electrolyte in fiberglass mats, which makes it spill-resistant and better at handling frequent starts, high accessory loads and partial states of charge. Many start-stop and high-load vehicles require AGM.
Replace a battery with the type the vehicle maker specifies. Downgrading from AGM to flooded can shorten battery life and upset the charging strategy. Set the battery type on your tester and charger correctly, and register the new battery with a scan tool if the vehicle requires it. Wear eye protection when handling batteries, since flooded types contain acid.
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General guidance only. Follow the vehicle and tool manufacturer's procedures, and confirm vehicle coverage on the tool maker's list before buying.