Deep-cycle batteries are a type of battery that is designed to be repeatedly discharged and recharged. They are commonly used in applications such as golf carts, RVs, and solar power systems. Regular maintenance is essential to maximize a deep-cycle battery's life. This includes inspecting the battery's fluid level and voltage after the charging service. You can use a hydrometer and DC voltage meter to perform these inspections.
Deep-cycle batteries may look like car batteries to unfamiliar people, but they're pretty different. A deep cycle battery is a lead battery designed to provide sustained power over a long period and run reliably until it is 80% discharged or more; at this point, it needs to be recharged. It is important to note that although deep cycle batteries can be removed up to 80%, most manufacturers recommend not discharging below 45% to extend the battery's life.
The discharge level is the “deep cycle” and stands in contrast to other types of batteries that provide only short bursts of energy before recharging. Precisely, a starter battery discharges only a tiny percentage — usually 2 to 5% —each time it is used.
Both flooded and sealed deep-cycle batteries share some of the same components, including:
Perhaps the most crucial consideration when choosing a deep-cycle battery is what you intend to use it for. Here are some situations that make a difference in the type of deep-cycle battery you choose:
If you’re looking for a deep cycle battery for a vehicle that remains level or a stationary application, a flooded deep cycle battery may be your best bet. Flooded batteries are the most common type of deep-cycle battery, and as such, they are generally easier to find and more cost-effective than other types of batteries. Because they use a liquid electrolyte, they can only be used uprightly. They should also be used in applications that allow easy charging, watering, and other maintenance access.
Examples: forklifts, renewable energy storage
In applications where temperature and required power draw vary, a VRLA battery, such as an AGM battery, may be the best option. Because VRLA batteries are sealed, there is less chance of damage or weathering of the inside components, which helps to ensure a longer lifespan and better performance. VRLA batteries can operate in any orientation, not just upright like flooded batteries, so they’re ideal for situations where they might frequently tip or are installed sideways.
In addition, VRLA batteries may be better suited when regular maintenance is complex. All deep-cycle batteries need to be charged according to manufacturer specifications, so some care is always required, but if you’re unable to water your battery frequently for whatever reason, you should consider buying a VRLA.
Before you troubleshoot a battery, be familiar with the potential risks of handling any battery. This includes wearing personal protection equipment (goggles, gloves, etc.); removing metallic objects such as jewelry, and working in an open, well-ventilated area. Before your inspection, ensure you fully charge the battery to get an accurate reading of the battery condition. Or, if you can’t charge the battery, let it sit for one hour after use.
You can often detect problems with your battery simply by looking for the following:
If your battery still performs poorly, you’ll find helpful troubleshooting ideas in our seasonal battery brochure for deep cycle and AGM batteries.
Just like with a car, don’t let minor problems with your battery go unnoticed; small issues can quickly lead to much bigger problems (and more expensive) problems later... and end up damaging your battery beyond repair. Get the most life out of your deep cycle battery by checking for small things and performing tests regularly.