What is an AGM battery?

An AGM battery is a lead-acid electric storage battery that has the electrolyte (acid) immobilized and absorbed into a woven glass fibre sponge-like material called an Absorbed Glass Mat (AGM):

  • Uses various grid thicknesses relative to application and cost requirements
  • Uses various Positive and Negative Active Material amounts and densities depending upon the application's needs.
  • Thin grid + low active material ratio & low active material density used in general purpose starting/float and light duty cyclic use.
  • Thick grid + high active material ratio & high active material density used in purpose-built Semi-Traction Industrial and General-Purpose Deep Cycle.
  • It is sealed using special valve-regulated pressure valves and should never be opened.
  • Quality AGM models use individual cell valves with built-in flame arrestors - IMPORTANT.
  • Typically uses Lead Calcium-tin metal alloy grids.
  • It is maintenance-free with proper charging controls.
  • Has its entire electrolyte absorbed in separators consisting of a sponge-like mass of woven glass fibre material.
  • Acid-to-active material ratios, along with acid-specific gravities may vary according to application and market costing requirements. *** User/integrator should note and verify.
  • It uses a recombination reaction to prevent the escape of hydrogen and oxygen gases usually lost in a flooded lead-acid battery (particularly in any cycling applications).
  • It is nonspillable.
  • It is better than GEL for high-vibration applications because of the cell compression provided by the absorbed glass mat.
  • It is better than GEL for high-rate discharge applications because of its lower internal resistance.
  • It is better than GEL in low-temperature performance.
  • It is generally compatible with vehicle alternator voltages.
  • It does not suffer as greatly from acid stratification compared to flooded battery technology because AGM technology completely absorbs and constrains the acid in a fibre separator making it more difficult for the acid to diffuse from the water to accumulate at the bottom of the battery’s cells. This restrained diffusion has been proven to slow the stratifying effect of gravity on battery acid in AGM battery technology. Acid Stratification is the #1 killer of flooded lead-acid batteries.

*** Available amounts of usable amp hours CAN BE ADJUSTED BY AS MUCH AS 30% by adjusting the acid and active material densities. Buyers should be aware that increasing acid-specific gravities and acid-to-active material ratios will severely reduce the batteries' life cycle expectancy and increase the available usable power per discharge cycle. For example, a 75-amp hour battery can deliver 100 amp hours by increasing the acid-to-active material ratio and the specific gravity of the acid. Both of these adjustments will severely reduce the life of the battery. Therefore, if you are quoted an unbelievable price on a 100AH battery given the current market pricing, you may now know why!