Valve-regulated lead-acid (VRLA) batteries, which include absorbed glass mat (AGM) and gel types, are ideal for use in applications where one or more of the following apply:
- Regular battery maintenance is difficult. This may be due to the system’s remote location or the fact that maintenance labor is too expensive.
- Local ordinances prohibit the use of flooded batteries due to environmental concerns about possible acid spills.
- A spill containment system may not be feasible for an installation.
- In places where heavy hydrogen off-gassing may pose a hazard.
- An installation where the batteries must lay on their sides.
- If batteries must be shipped, VRLAs can usually be classified as nonhazardous cargo. Shipping these batteries is usually less expensive than shipping flooded lead-acid batteries.
- AGM batteries are better suited for very cold temperatures: the battery’s internal resistance is lower and the charge acceptance is better than FLA and gel-type batteries. Also, the specific gravity of an AGM battery’s electrolyte is higher, so is less subject to freezing.
- In applications that require very high discharge rates, such as UPS backup power, AGM technology is a good fit because of their lower internal resistance (compared to flooded batteries of equal capacity). Not all AGM batteries are designed for high power rates. Only those batteries designed to work within high-energy demands of deep-cycle applications are best for RE applications.