Posts

Renewable Energy Storage Options: AGM vs FLA Batteries

Energy-conscious businesses and homeowners who are looking to store energy from their wind or solar energy systems, often consider the differences between using a no-maintenance AGM (Absorbed Glass Mat) and an FLA (Flooded Lead-Acid) deep-cycle batteries. While each type of battery has its advantages, here are some facts that can help you make the right decision for your particular application.

 

Higher Cost, Lower Maintenance

 

If you want a low maintenance renewable energy system’s battery bank, a set of AGM batteries are the ideal choice. Deep-cycle models can be successfully used for energy storage. Because they are sealed and featured glass matt separators that retain all of the electrolyte without water, there’s no need to periodically add water.

 

The drawback, according to U.S. Battery Senior VP of Engineering Fred Wehmeyer, is the cost. “AGM batteries typically cost from 25 to 50 percent more per watt-hour compared to FLA batteries,” says Wehmeyer. “Besides, AGM batteries may also not last as long as premium FLA batteries used in these types of applications.”

 

Lower Cost, Higher Maintenance

 

When lower total operating costs are the goal, FLA batteries offer the lowest cost per watt-hour than any other type of battery storage system available. According to Wehmeyer, deep-cycle FLA batteries are robust and have been used very successfully for energy storage for several decades. “Less expensive than AGM batteries, FLA batteries offer the best cost per watt-hour than any other energy storage method available,” says Wehmeyer.

 

If you’re not opposed to routine maintenance, Wehmeyer adds that premium FLA batteries (those with higher lead content) will last longer than AGM batteries. Because FLA batteries lose water from evaporation during charging, they need to be regularly replenished, as well as cleaning and checking the terminals. Wehmeyer also recommends to occasionally performing an equalization charge on FLA battery banks used for energy storage. “Equalization charging is extremely important to optimize the life of renewable energy batteries,” he says. “It is used to both balance the individual cells in a battery pack and to mix the electrolyte through gassing to prevent electrolyte stratification.”

 

Gaining Optimum Performance From Both

 

No matter what type of batteries you choose for your renewable energy storage, deep-cycle batteries work best when the depth of discharge of your battery bank is kept to 50-percent. “For best performance and longest life, the batteries should be fully recharged regularly,” says Wehmeyer. “Depending on the source of recharge provided (solar, wind, generator, or AC power), full charging may not always be possible every day. Most batteries can operate efficiently in a partial state of charge condition as long a full charge is done at least every 30 days.”

AGM and Flooded Deep-Cycle Batteries

Understanding the Differences Between AGM And Flooded Deep-Cycle Batteries

When it comes to powering electric vehicles like golf carts, deep-cycle lead-acid batteries are the industry standard. The reason is that they are designed to provide the most cost-effective energy storage and delivery over the life of the battery.

Over the years, there have been two main types of deep-cycle lead-acid batteries that many golf car owners and fleets have used, the Flooded Lead-Acid (FLA) battery and the Absorbed Glass Mat (AGM) battery. While both provide optimum performance in a wide variety of applications, their design difference can offer various advantages depending on the application.

Engineering

The main design difference between FLA and AGM batteries is how the electrolyte is managed. In FLA batteries, the battery plates are submerged in the liquid electrolyte. During use, water in the electrolyte is broken down into oxygen and hydrogen gases and water is lost. This requires regular additions of water to be replaced to keep the battery plates fully submerged in the electrolyte.

In AGM batteries, the electrolyte is absorbed in special glass mat separators that retain all the electrolyte needed for the life of the battery.  Since there is no free electrolyte, the oxygen generated on a charge is recombined at the negative plate.  In normal operation, hydrogen is not generated and no water is lost.  This eliminates the need to add water and also allows the battery to be sealed with a one-way valve that prevents leakage of the electrolyte.

Performance Differences

FLA batteries have been used in a wide variety of applications for well over 150 years. Their popularity comes from their safety, reliability, and cost-effectiveness when compared with other types of rechargeable batteries.   According to Fred Wehmeyer, U.S. Battery Senior VP of Engineering, FLA batteries deliver the lowest cost per watt-hour both in acquisition cost and in overall cost per charge/discharge cycle.  “This is why they are the best choice for fleets of vehicles or equipment that are used heavily on a daily basis,” says Wehmeyer. “Also, both FLA and AGM batteries offer an environmental advantage over other types of batteries because they are essentially 100 percent recyclable and enjoy the highest recycling rate of any commercial product.”

AGM batteries offer the advantage of being maintenance-free. This can be significant in applications where regular maintenance is difficult or costly, such as when the batteries are located in remote or hard to access locations. Even though AGM batteries cost more per watt-hour, the elimination of maintenance costs reduces the overall battery operational costs.  Also, since the battery is sealed and does not emit gases in normal use, it can be used in sensitive areas such as food or pharmaceutical storage facilities.

Selecting between FLA or AGM deep cycle batteries ultimately depends on the type of use and the capability to provide regular maintenance in the application.

AGM = No Maintenance + Higher Cost + Susceptible to abuse like overcharging

FLA = Requires Watering + Lower Cost + Susceptible to abuse from poor maintenance

No matter what type of battery you use, it is always best to target the depth of discharge to 50 percent or less for both FLA or AGM battery types. This will optimize battery life cycle cost vs acquisition cost over the life of the battery system.

 

US AGM12V27

Best Uses For AGM Deep-Cycle Batteries

When it comes to powering electric vehicles like golf carts, cleaning machines, and marine/RV accessories, deep-cycle batteries are the industry standard. The reason is that they are designed to provide greater long-term energy delivery that is capable of powering vehicles and equipment for longer periods of time, compared to a battery used to start a vehicle.

Deep-cycle absorbed glass mat (AGM) batteries were designed with the electrolyte soaked into absorbed glass mats that surround the battery’s cell plates, rather than being submerged in the liquid electrolyte like the Flooded Lead-Acid battery types. The absorbed glass mat design eliminates the need to add water and prevents any leakage of the electrolyte in cold or hot weather conditions.

Without the need to add water, these maintenance-free, batteries offer an advantage when used in compact, battery-powered vehicles and equipment. Many of these have very small battery storage spaces, where access to the batteries is difficult. If you live or use battery-powered equipment in extremely cold environments, AGM batteries are well suited for it, as there’s no free liquid to freeze and expand, which cause battery case damage.

AGM deep-cycle batteries are available in a wide range of sizes and voltages that can be used in just about any application from RVs, to Solar and Renewable energy storage, golf cars, aerial work platforms, floor cleaning machines and more.