Deep-cycle marine batteries are specialized power sources designed to deliver steady and stable power output over extended periods of time. They offer excellent durability and longevity, robust safety features, and efficient energy use management.
This guide explores the unique features and performance advantages of deep cycle marine batteries. It also compares four major subtypes to help you choose the right battery for your needs.
What Are Deep Cycle Marine Batteries?
Deep cycle batteries deliver a continuous power supply. Compared to starting batteries, they offer:
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Greater Discharge Depth: Deep cycle batteries use 80% or more of their total power, so you can do more with a single charge. In contrast, starting batteries typically have a discharge depth of only about 50%.
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Longer Cycle Life: You can recharge a deep cycle battery thousands of times. Starting batteries have far less cycle life, requiring much more frequent replacement.
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Lower Maintenance Requirements: Deep cycle batteries need little or no maintenance. Meanwhile, starting batteries require regular checks and tune-ups to ensure they perform as expected.
In marine environments, deep cycle batteries provide a reliable and constant source of power. They’re ideal for a boat’s house appliances and necessities, trolling motors, fish finders, and on-board electronics that continually run, while starting batteries are mostly rated for intermittent use.
Advantages of Deep Cycle Marine Batteries
Deep cycle batteries offer a long list of performance and practical advantages over starting batteries. For instance:
Sustained Power
Standard starting batteries supply large amounts of power but in short bursts. Deep cycle batteries release power in smaller amounts but in steady and consistent outflows. This makes them well-suited to applications requiring a continuous source of energy, such as appliances and onboard electrical systems.
Durability
Deep cycle batteries offer superior durability and excel in even the most challenging marine environments and conditions. Many of them can easily withstand dramatic temperature fluctuations and maintain performance during extreme turbulence.
Versatility
Deep cycle marine batteries can be used for just about any onboard application that requires a consistent power supply. This includes appliances, trolling motors, lighting systems, and electronic equipment.
Long Lifespan
Deep cycle batteries have much longer lifespans than standard rechargeable starting battery systems. A top-performing lithium-ion deep cycle battery can be recharged up to about 5,000 times, while standard starting batteries can only withstand a few hundred recharging cycles.
Due to their superior recharging capabilities, deep cycle batteries can easily last 10 years or longer. Meanwhile, typical lead-acid starting batteries have lifespans of just 3–5 years.
Types of Deep Cycle Marine Batteries
Manufacturers produce many deep cycle battery subtypes with unique features and performance capabilities. Here’s a run-down of four popular battery types:
Flooded Lead Acid
Flooded lead-acid deep cycle batteries use liquid electrolytes to submerge their lead plates in free-flowing liquid completely. While they require more maintenance than some other deep cycle batteries, they’re very reliable if properly maintained and offer appealing cost advantages.
Gel Lead Acid
These batteries use sealed, gel-based electrolytes instead of liquid, so they won’t spill or leak and need little maintenance. This makes them safer and better at operating in extreme temperatures than flooded lead acid.
Absorbent Glass Mat (AGM)
AGM deep cycle batteries also use sealed lead-acid designs but incorporate fiberglass mats. These hold and stabilize electrolyte solutions while allowing them to retain their charges for longer periods of time when not in use.
Like gel lead-acid batteries, AGM deep cycle marine batteries are spill-proof, leak-proof, and don’t require nearly as much maintenance.
Lithium (LiFePO4)
Standard lithium-ion deep cycle batteries feature lightweight and compact designs that make them ideal for mobile use and marine applications. These batteries use safe, stable, non-toxic chemical technologies. What’s more, their built-in battery maintenance system (BMS) prevents overcharging, overheating, and short circuiting and facilitates deep discharges.
How To Choose the Right Deep Cycle Marine Battery for Your Boat
To choose the right deep cycle battery for your marine application, consider the following key performance factors:
Battery Capacity (Amp Hours)
Manufacturers often express battery capacity in terms of amp hours, which quantify the length of time the battery can supply 1 ampere of power output per hour. In practical terms, you must consider the power input needs of the appliances, equipment, and systems the battery will power.
For an easy point of comparison, look at the amp hour (Ah) ratings of various batteries you’re considering. When used for similar applications under similar conditions, a deep cycle battery with a capacity rating of 10Ah will operate about twice as long as one with a 5Ah output rating.
Battery Discharge Rate (C Rate)
C rates describe the rate at which a battery charges and discharges its power supply relative to its total capacity. It quantifies how quickly a battery can acquire or release its charge without damaging any connected equipment.
The C rate is expressed as a multiple of the battery’s amp hour capacity. A rate of 1C means the battery will discharge its capacity in one hour. The lower the C rate, the longer the battery’s discharge time: 0.5C implies the battery will discharge its capacity in two hours, while a 2C rate means it will discharge its capacity in just 30 minutes.
Battery Cycle Life
Battery cycle life indicates how often a battery can be charged and discharged before it suffers a permanent performance loss. Your battery will near the end of its life once it comes within about 80% of its manufacturer-specified cycle life.
Weight and Size
The Battery Council International (BCI) has created a standardized system for rating marine batteries’ weight and size. Specific vessel types require certain sizes. A BCI sizing chart can help you find battery groups compatible with your intended application.
Maintenance Tips for Deep Cycle Marine Batteries
Deep cycle marine batteries are engineered for low maintenance. However, following a few best practices can extend the battery’s lifespan and protect its performance capabilities.
Check for Corrosion and Good Connections
On lead-based batteries, inspect for signs of corrosion and remove any you find with a mixture of water and baking soda. Check all terminals and tighten loose connections.
Optimize Your Charging Practices
Take advantage of your deep cycle battery’s depth of discharge features. It’s designed to be drained to very low levels without causing damage. Ensure your charger has the proper voltage rating and stop charging when the battery reaches full capacity. Also, consider using a charger with an automatic shutoff to prevent overcharging.
Store Your Battery Correctly
Follow best practices for storage during the off-season and any other time you’re not using your deep cycle marine battery:
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Keep the battery dry and away from condensation and humidity.
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Avoid temperature extremes. Try to keep the battery between 32 and 80 degrees Fahrenheit (0 and 27 degrees Celsius).
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Label your batteries to prevent confusion and keep them in an accessible location.
Find the Perfect Deep Cycle Batteries for Your Marine Application
Deep cycle marine batteries bring numerous advantages, but several factors must be considered as you compare your options. Understand your performance needs and select the correct type of battery for your boating adventure.
Battle Born Batteries has a complete inventory of deep cycle lithium-ion batteries. Contact us today to find the ideal deep cycle marine battery for your marine and offshore needs.
