In the context of renewable energy systems involving solar, wind or hydro energy, when batteries are being mentioned, it usually refers to deep cycle batteries. Therefore, it’s common that the average homeowner powering his home off grid has a lot of questions concerning this kind of battery. If you too were googling to find out something more about the best battery that can power your eco-friendly home or take it with you on camping trips, this is your guide.
What is a Lead Acid Deep Cycle Battery?
Deep cycle batteries are energy storage units that have a chemical component, usually lead acid, which triggers a reaction that results in voltage and electricity. The term cycle refers to the ability of the battery to be discharged and recharged for multiple cycles. Opposed to starter batteries, like a car battery for example, that offer a short burst of energy and discharge only a small part of their capacity, a deep cycle battery delivers a steady flow of current over a longer period.
What Types of Deep Cycle Batteries are There?
Deep cycle batteries are divided into two distinct types: flooded (FLA) and sealed or also known as valve regulated (VRLA) batteries. The most commonly used type of lead acid deep cycle battery is the flooded one, which is also called wet cell. The terms flooded or wet cell is used because this kind of battery has its plates completely submerged in an electrolyte fluid. This means that in order for the battery to function properly, it needs to be kept upright at all times and regularly monitored. The reason why these types of batteries are so well-liked, is because they have a high surge current, are easier to troubleshoot and are affordable.
Sealed lead batteries (VRLA) are further distinguished into absorbed glass mat (AGM) and gel. The ones that use absorbed glass mat separators can experience less damage from spilling and jolting vibrations. Gel batteries contain a gel electrolyte, which unlike FLA batteries do not have to be kept upright. Gel cells experience less electrolyte evaporation which is common with FLA. However, they are more expensive than the other types of lead acid deep cycle batteries and are therefore mostly used in boats, aircrafts and other motorized vehicles for mass transport.
What is the Discharge Rate?
The lifespan of a lead acid deep cycle battery is impossible to predict with certainty. There are many factors at play such as depth of discharge, temperature, maintenance, how deep cycled the battery gets, and more. However, studies on these batteries were able to pinpoint the average discharge rate that varies for different applications.
- Starting battery: 3-12 months;
- Marine: 1-6 years
- Industrial deep cycle: 10-20 years
- Telephone: 2- 10 years
- Solar systems: 4+ years
Are There any Safety Hazards?
Like with any other type of battery, deep cycle batteries can experience explosions. These explosions are usually caused by overcharging the battery beyond its capacity. Besides explosions, an overcharged battery can experience leakage or release hydrogen. If this gas is ignited by a nearby spark, the result can be devastating. Therefore, you need to be extra careful not to overcharge this kind of battery.
