AGM

📖 YOUCANIC Automotive Glossary

AGM (Absorbent Glass Mat) is a type of sealed lead-acid battery where the electrolyte is absorbed into fiberglass mat separators between the plates rather than being free-flowing liquid. AGM batteries are specifically designed for vehicles with ISG (start-stop) systems, regenerative braking, and high electrical demands because they accept charge faster, handle deep cycling better, have lower internal resistance, and recover from discharge more quickly than conventional flooded batteries. AGM batteries also mount in any orientation without leaking, resist vibration damage better, and have a lower self-discharge rate.

AGM batteries cost 2-3x more than standard flooded batteries but are essential for vehicles designed for them. Replacing an AGM with a standard flooded battery on a vehicle with start-stop or intelligent charging causes premature battery failure, start-stop deactivation, and potential charging system damage. After replacement, Battery Registration (BRT) through the YOUCANIC UCAN-II must specify AGM battery type so the charging system applies the correct voltage profile. Overcharging an AGM battery (above 14.8V) causes irreversible damage — the sealed design means lost water cannot be replaced.