Batteries FYI

Gel vs. AGM vs. Wet Cell Batteries

Gel vs. AGM vs. Wet Cell Batteries


One of the most important decisions when designing a stand-alone power system is deciding the best battery for the application. Gathering information about the site’s maximum summer and lowest winter temperatures, the duration of extreme conditions, accurate load and duty-cycle information, and charge and discharge cycles are all key factors in battery selection.

Failure to make the right decision based on area classifications, power cycle life, maximum environmental temperatures, and maximum low temperatures are all factors that can lead to safety issues, the early death of a battery, and the unexpected failure/loss of control, measurement, communications, or UPS systems. Be sure to consult a specially trained technician to design stand-alone power systems using the following information as a guide.

Gel Cell, Absorbed Glass Mat (AGM), and Wet Cell are various versions of lead acid batteries. The Wet comes in two styles: serviceable, and maintenance free. Gel Cell and the AGM batteries are specialty batteries that typically cost twice as much as a premium Wet Cell battery. However, Gel cell and AGM batteries do not tend to sulfate or degrade as easily as Wet Cell. As a result, there is little chance of a hydrogen gas explosion, or corrosion of electrical components and wiring in close proximity when using these batteries. In most cases AGM batteries will give longer life span and greater cycle life than a Wet Cell battery.

What is the difference between Gel Cell and “(AGM)” Absorbed Electrolyte batteries?

AGM batteries are typically good deep cycle batteries and they deliver their best life performance if recharged before the battery drops below the 50 percent discharge rate. These batteries typically have a shorter life cycle than Gel Cell batteries (as much as ½). They are often best used in applications requiring higher charge and discharge currents such as those in a UPS backup power system.

The recharge voltages of Gel Cells are lower than the other styles of lead acid battery. Gel Cell batteries are best used in very deep cycle application and may last a bit longer in hot weather conditions. The selection of battery chargers with Gel Cell batteries is critical because using an incorrect battery charger with a Gel Cell battery will cause poor performance and premature battery failure.

What is the difference between Gel Cell/AGM and traditional Wet Cell batteries?

Wet Cells contain liquid electrolyte that can spill if tipped or punctured, causing corrosion to affected areas. Therefore, they are not air transportable without special containers. They cannot be shipped via UPS or Parcel Post, and should not be used near sensitive electronic equipment. They can only be installed “upright.”

Can Gel Cells be installed in sealed battery boxes?

NO! Never install any type of battery in a completely sealed container. Although the normal gasses (oxygen and hydrogen) produced in a Gel Cell battery will recombined and not escape, oxygen and hydrogen can escape from the battery in an overcharged condition (as is typical in any type battery).

For safety’s sake, these potentially explosive gasses must be allowed to vent to the atmosphere and must never be trapped in a sealed battery box or tightly enclosed space.


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