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.”