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What is an AGM Battery?

An AGM (absorbed glass mat) battery contains a special glass mat separator that wicks the electrolyte solution between the battery plates. This material's design enables the fiberglass to be saturated with electrolyte – and to store the electrolyte in a “dry” or suspended state rather than in free liquid form.

Perks: Because they do not contain a liquid that could potentially freeze or evaporate, these batteries work better in extreme climates than flooded batteries. Whether you are experiencing extremely high or low temps, AGM batteries will continue to function, even when stored in those temperatures.

AGM batteries are extremely durable, vibration resistant, and will continue to function if slightly damaged or cracked. They hold a charge even if not used regularly, making them a good solution for seasonal equipment and vehicles with batteries stored during “off-seasons.”

Pros: These batteries are referred to as maintenance-free batteries and do not require watering service. Since there is no free liquid and minimal gassing, AGM BATTERIES can perform better than flooded batteries in applications where maintenance is difficult to perform.

Cons: Users should take care when charging this battery as over, and undercharging can affect their lives and performance. AGM batteries perform most reliably when their use is limited to discharge of no more than 50% of battery capacity.


  • Can last longer for years.
  • Can be easily recharged, sometimes up to 5 times faster.
  • Have a low internal resistance.
  • Perform well in temperatures below 32 degrees.

Frequently Asked Questions & Answers

AGM batteries do not require a special charger. However, it will benefit from the ministration of a quality "smart" charger like any other battery. A regular old constant voltage charger, such as you'd buy at the local auto parts store, feeds out power at around 12.7v (some are 12.6v, and some are 12.8v).

AGM is maintenance-free, provides good electrical reliability, and is lighter than the flooded lead-acid type. It stands up well to low temperatures and has a low self-discharge. The leading advantages are a charge up to five times faster than the flooded version and the ability to deep cycle.

Generally, an AGM battery can last two to three times as long as a flooded battery. In the commuter car example we referenced, if a flooded battery lasts three to five years, an AGM battery could last six to ten years or longer

While regular lead acid batteries need a topping charge every six months to prevent sulfation build-up, AGM batteries are less prone to sulfation and can sit in storage for longer before a charge becomes necessary. The battery stands up well to low temperatures and has a low self-discharge.