Understanding House Batteries: Powering Your Boat's Electrical System

A house battery on a boat is a type of battery that provides power for the boat's running load. This includes accessories like lights, trolling motors, depth finders, and other onboard technology. House batteries are designed to deliver smaller amounts of power over a longer period of time compared to starting batteries, which provide a large burst of power to turn over the engine. House battery banks are typically deep cycle batteries, which have thicker plates and can withstand more service cycles. The number of house batteries required depends on the number of additional applications and the power requirements of those applications.

Characteristics of a House Battery on a Boat

Deep cycle batteries

Deep-cycle batteries are a crucial component of any boating system. They are designed to provide a stable power supply for extended periods, ensuring that your devices and equipment receive the optimal voltage to function effectively. These batteries are commonly used to power trolling motors, navigation systems, fish finders, and other marine accessories.

Deep-cycle batteries are engineered to withstand repeated charging and discharging cycles. They are constructed with thicker plates compared to starter batteries, allowing for more service cycles. This design feature also makes them less susceptible to warping, potential shorting, and catastrophic failure.

When selecting a deep-cycle marine battery, you will find various options, including flooded lead-acid, absorbed glass mat (AGM), and lithium-ion batteries. Flooded lead-acid batteries are traditional options that offer long life and excellent lifetime cost but require regular maintenance. AGM batteries, on the other hand, are sealed and maintenance-free, offering high vibration resistance and a low self-discharge rate. Lithium-ion batteries are also maintenance-free and offer higher energy density, resulting in reduced weight. However, they are more prone to thermal runaway and fires, and their operating and charging temperature ranges are more restricted.

It is important to choose the right capacity for your deep-cycle marine battery. Too little capacity can leave you without power, while too much capacity can be wasteful and costly. Calculate your energy requirements by estimating the energy consumption of each device and the number of hours of operation between charging cycles.

Deep-cycle marine batteries are widely available from various manufacturers, including Duracell Ultra, Weize, Newport, Renogy, ExpertPower, OPTIMA, and VMAX, offering a range of features and specifications to meet your boating needs.

Dual-purpose batteries

A house battery on a boat is part of the boat's electrical system and is used to power onboard DC loads such as lighting, trolling motors, inverters, and other systems. These batteries are typically deep-cycle batteries, which can withstand repeated deep discharging and recharging without sustaining damage.

When choosing a dual-purpose battery, it's important to consider the boat's weight, size, and specific power needs. Higher amp hours mean your boat can run longer on a single charge. Abyss Battery®, for example, offers a range of 12V dual-purpose lithium marine batteries that are designed for both high-demand starting and deep-cycle applications. Their batteries are approved for use with Mercury Marine, Yamaha, Suzuki Marine, and Honda Marine Outboard engines.

Starting batteries

When selecting a starting battery, it is important to consider the specific requirements of your boat's engine. The battery's CCA rating should meet or exceed the engine's requirements. Other factors to consider include the battery's reserve capacity, which is the steady power it can provide when the alternator is not operating, and its amp-hour rating, which indicates how much energy it can store.

AGM Sealed Batteries are a popular choice for starting applications as they charge quickly and have a low self-discharge rate of 3% per month.

Battery maintenance

House batteries are an essential component of a boat's electrical system, powering everything from the engine to electronics and accessories. They are designed to handle the unique challenges of the marine environment.

• Battery type and application: Understand the difference between starting (cranking) batteries and deep-cycle house batteries. Cranking batteries deliver quick bursts of energy to start the engine, while deep-cycle batteries provide consistent power over a long period for electronics and appliances. House battery banks should be deep-cycle batteries with thicker plates to allow for more service cycles.
• Charging: Proper charging is crucial for extending the life of your house batteries. Use a charger designed specifically for marine batteries to avoid overcharging or undercharging. Different types of batteries require different charging voltages. For example, a 12-volt deep-cycle battery should be charged to around 14.4-14.8 volts. Consider using a trickle charger to maintain battery health when your boat is not in use.
• Battery connections: Regularly check the battery terminal connections to ensure they are tight and free from corrosion. Clean the terminals with a mixture of baking soda and water if necessary.
• Battery storage: Keep your batteries cool and out of direct sunlight to prevent overheating. Secure them with a battery box or tray to minimise vibration damage, especially in rough water.
• Battery maintenance for infrequent use: If you don't use your boat often, use a maintenance-type battery charger to keep the batteries fully charged between outings. Before off-season storage, fully charge the batteries, then disconnect the terminals. If possible, store the batteries in a cool location and recharge them periodically to prevent deep discharge.
• Preventing issues: Watch out for common issues such as sulfation, which can be prevented by regularly charging your battery. Check for parasitic loads if your battery drains quickly, and consider replacing old batteries that hold less charge.
• Battery replacement: Marine batteries typically last 3-5 years, but this depends on use and maintenance. Signs that it's time to replace your battery include slow cranking, swelling or leaking, and reduced capacity. Consult a marine dealer or your boat owner's manual when replacing a battery.
• Battery disposal: Dispose of old batteries responsibly by taking them to a recycling centre or returning them to a marine supply store.

Battery chemistry

Marine batteries are available in three types: starting, deep-cycle, and dual-purpose. Each type is offered with a choice of battery chemistries, including flooded lead acid, gel, AGM (Absorbed Glass Mat), and Lithium Iron Phosphate. The choice of battery chemistry depends on the performance desired and the budget.

Flooded lead-acid batteries are the most traditional form of marine battery, typically found aboard boats. They are made of lead plates and acid, with a blend of distilled water and sulfuric acid. These batteries are large, heavy, and require frequent replacement, making them a costly option in the long run. They also have the longest charging times on the market and need to be stored in a ventilated area to prevent the release of hydrogen gas.

Sealed lead-acid batteries are either of the absorbed glass mat (AGM) type or gel type. In AGM batteries, the battery plates are protected by fine-stranded glass mats, while in gel batteries, the liquid electrolyte is converted into a gel. These batteries are more durable, leak-proof, and can withstand more charge-discharge cycles than conventional deep-discharge batteries. However, they have lower storage capacity and are more expensive than flooded lead-acid batteries.

Lithium Iron Phosphate (LiFePO4) batteries are a newer option for marine use, offering portability, lightweight construction, durability, and quick recharge times. They are safe to drain to below 50% and can be recharged faster than lead-acid batteries. Additionally, they do not require maintenance and can be safely discharged to 70-80% of their rated capacity. However, they are sensitive to temperature changes and require specific chargers to prevent damage.

Frequently asked questions