The majority of batteries found in most modern-day vehicles are lead-acid and offer a very good compromise between reliability, usability, robustness, availability and price.
Absorbed Glass Mat (AGM) batteries, along with Flooded (or Wet Cell), Gel Cell, and Enhanced Flooded Batteries (EFB) are sub-sets of lead-acid batteries.
AGM and EFB batteries are characterised by their high performance and thanks to advances in battery technology, they need less maintenance and are more reliable than 10 years ago.
Conventional flooded batteries are the most common and economical lead-acid chemistry and are suitable for conventional vehicles. Some are classified as SMF (Sealed Maintenance Free), where no maintenance of the electrolyte levels is required.
Enhanced Flooded Batteries are referred to as EFB’s and are designed for Start-Stop applications. They are different to Conventional Batteries in that: They cycle better, they accept charge better, and they have a wider operating range of temperatures.
Increasingly used as replacements for conventional batteries, EFB’s must only be used in vehicles whose electrical systems are designed for EFB’s or Conventional Batteries.
Absorbed Glass Mat Batteries are referred to as AGM’s and are valve regulated lead acid (VRLA) batteries. Valve Regulated batteries are equipped with a pressure release valve for safety and oxygen recombination. AGM’s offer better performance than Conventional Batteries in that: They cycle better, they accept charge better and they have no water loss.
AGM’s must only be used in vehicles whose electrical system was designed for these batteries.