what is an agm marine battery

Absorbent Glass Mat (AGM) Battery Technology

Absorbent Glass Mat is a type of lead-acid electrical energy storage device characterized by its internal construction and operational advantages. It utilizes a unique design where the electrolyte is absorbed into a fiberglass mat, setting it apart from flooded lead-acid types.

Construction and Operation

  • Electrolyte Absorption: The electrolyte is held within a fine fiberglass mat, rather than being free-flowing. This minimizes the risk of spills and allows for installation in various orientations.
  • Sealed Design: Typically sealed, reducing water loss and maintenance requirements. Venting mechanisms are incorporated to release pressure in overcharge or extreme conditions.
  • Lead-Acid Chemistry: Employs the same fundamental lead-acid chemistry as traditional batteries, involving chemical reactions between lead plates and sulfuric acid electrolyte.

Advantages

  • Reduced Electrolyte Stratification: The absorbed electrolyte minimizes stratification, leading to more efficient charging and discharging.
  • Lower Self-Discharge Rate: Typically exhibits a lower self-discharge rate compared to flooded batteries, allowing for longer storage periods.
  • Vibration Resistance: The robust construction and immobilized electrolyte provide enhanced resistance to vibration and shock.
  • Maintenance-Free Operation: Sealed construction reduces the need for regular maintenance tasks such as water replenishment.
  • Versatile Mounting: Can be mounted in various orientations without the risk of electrolyte leakage (with the exception of being inverted).

Applications

Due to their properties, these units find use in a wide array of applications. Common uses include:

  • Power sports equipment (motorcycles, ATVs)
  • Uninterruptible power supplies (UPS)
  • Alarm systems
  • Mobility devices (wheelchairs, scooters)
  • Solar power storage

Considerations

  • Charging Requirements: Requires specific charging profiles to avoid overcharging and damage. Using an inappropriate charger can significantly reduce lifespan.
  • Temperature Sensitivity: Performance can be affected by extreme temperatures. Optimal operating temperature ranges should be observed.
  • Cost: Generally more expensive than flooded lead-acid types.