Best Places To Install A Power Inverter On Your Boat

Inverters are now standard on cruising boats, but installing one requires some know-how. Inverters convert power from DC batteries to AC current, and most can also reverse this process to charge batteries. Inverters require specific fuses, and the positive cable must be protected by a fuse installed close to the power source. The inverter's DC supply cabling should also be equipped with a disconnect switch for servicing and safety. Inverters should not be installed on horizontal surfaces or above battery banks, and the chassis must be bonded or grounded. The AC cables should pass through the inverter's case using strain-relief connectors or cord grips to prevent accidents and electrocution. When installing an inverter, it is important to follow manufacturer instructions and safety guidelines.

Inverters vs. Gensets

When it comes to powering appliances on your boat, you have two main options: inverters and gensets. Both have their advantages and disadvantages, so it's important to understand the differences between them to make an informed decision.

Inverters

Inverters are devices that convert the 12-volt DC power from your boat's batteries into 120-volt AC power, which is what most household appliances use. They are a quiet, clean, and compact option, making them ideal for boats with limited space. Inverters can provide up to 3000 watts of power, which is enough to operate microwave ovens, toasters, TVs, and other appliances. They are also relatively easy to install and can function as battery chargers when plugged into shore power.

However, one limitation of inverters is that they draw energy from your boat's batteries, which have limited energy storage. This means that you'll need to carefully manage your power usage and consider adding more batteries if you plan to use high-power appliances. Additionally, inverters can generate significant heat when powering large loads, so adequate ventilation is crucial.

Gensets

Gensets, on the other hand, are engine-driven alternators that convert the energy in gasoline or diesel fuel into electrical energy. They can provide as much AC power as you need for as long as the fuel lasts, making them suitable for boats with higher power demands or those that require continuous power supply. Gensets are also quiet, especially when fitted with sound shields and exhaust systems that separate cooling water from the exhaust gas.

However, gensets have their drawbacks. They take up valuable space on your boat and can be costly to install. Additionally, running the genset's engine for extended periods, especially when anchored near other boats, may be frowned upon by your fellow boaters due to the noise and fumes.

So, which option is right for you? If you have modest power needs and don't require continuous power, an inverter is a great choice. It's quiet, compact, and relatively inexpensive. However, if you have higher power demands or need continuous power, a genset is the way to go. While gensets are more costly and take up more space, they provide unlimited power as long as you have fuel. Ultimately, the decision depends on your specific power requirements and budget.

Battery capacity requirements

To ensure optimal performance, it is recommended to follow the design rule that suggests inverters should have access to a battery bank that is 20% as large in amp-hours as the inverter size in watts. This means that a 1000-watt inverter should be supported by a battery bank of at least 200Ah capacity. This rule is based on the understanding that inverters consume approximately 100Ah of electricity for every 1000-watt-hours of use. Therefore, a 1000-watt inverter operating at maximum capacity for an hour would deplete a 200Ah battery by 50%. While this is the recommended minimum, it is always beneficial to have more battery capacity available.

When calculating the required battery capacity for your inverter, it is essential to consider the electrical loads you anticipate using. Appliances and electronics typically have their wattage listed on a back panel. If only the amp rating is provided, you can calculate the wattage using the formula: Volts x Amps = Watts. For example, a 7-amp microwave at the standard North American voltage of 115V would require 805 watts of power to function. By multiplying the wattage of each appliance by the expected hours of usage per day and then dividing the result by 10, you can estimate the amp-hours consumed from your batteries.

Additionally, it is important to account for the surge requirements of appliances. Many devices will exceed their estimated wattage, sometimes by 2-3 times, when they are initially turned on. Therefore, it is crucial to select an inverter that can accommodate these surge requirements to ensure your appliances function properly.

In summary, when determining the battery capacity requirements for your power inverter, follow the design rule of a 20% ratio between inverter size and battery capacity, calculate the electrical loads of your appliances, and ensure your inverter can handle the surge requirements of your devices. By considering these factors, you can make an informed decision regarding the battery capacity needed to support your power inverter.

Installation safety

When installing a power inverter on your boat, safety should be a top priority to prevent accidents and ensure compliance with regulations. Here are some essential installation safety guidelines to follow:

• Consult a Qualified Electrician: If you are not confident in your electrical skills or have limited experience, it is strongly recommended to consult a qualified marine electrician. They can guide you through the process and ensure that the installation is safe and compliant with regulations.
• Location: Choose a suitable location for the inverter, following the manufacturer's recommendations. It is ideal to place it close to the batteries to minimise wire length and cost. However, do not install the inverter directly above the batteries, especially if they are lead-acid batteries that release corrosive gases.
• Fusing: Follow the manufacturer's recommendations and industry standards, such as ABYC standards, for precise fusing. Ensure the fuse is located close to the batteries and is the correct type and size.
• On/Off Switch: Include an on/off switch on the DC-positive inverter wiring. This is crucial for servicing and ensures that the inverter can be turned off when needed.
• Battery Connections: Use single-core DC cables to connect the inverter's positive (+) and negative (-) terminals to the battery bank. Ensure these connections are secure and properly insulated.
• In-line Fuse Block: Install a fuse on the positive cable, close to the battery. Use a MEGA or MAXI fuse for appliances with high inrush currents.
• High-Current On-Off Switch: Install a high-current on/off switch between the fuse and the battery. This allows for easy disconnection of the inverter during maintenance or to prevent battery drain.
• Cable Sizing: Refer to the manufacturer's manual for recommended cable sizes. If no guidance is provided, calculate the required size based on the inverter's wattage, battery voltage, and efficiency, and then add a safety margin.
• Trunking: Protect AC cables with trunking to prevent accidental damage or contact. This adds an extra layer of safety and helps comply with regulations.
• Testing: Have a marine electrician test and commission your installation to ensure it meets safety standards and complies with regulations.
• Disconnect Power: Always disconnect the battery and inverter before performing maintenance or making adjustments to the system. This is a critical safety precaution.
• Ventilation and Accessibility: Install the inverter in a well-ventilated area to prevent overheating. Ensure the installation location is easily accessible for maintenance and future upgrades.
• Grounding: Properly ground the inverter to the boat's electrical system. Follow the manufacturer's instructions for grounding connections and ensure they meet industry standards.
• Compliance with Regulations: Ensure that your installation complies with marine electrical regulations, such as ABYC standards. This includes proper labelling, fusing, wiring, and grounding practices.
• Avoid Explosive Environments: Do not install the inverter in a potentially explosive environment, such as a gasoline engine room. Inverters are not ignition-protected and must be placed in a safe location.

Inverter types

There are several types of inverters available, each with its own advantages and disadvantages. Here are some of the most common types:

• Portable Inverters: These inverters are typically small and lightweight, making them easy to carry and store. They usually connect to your boat's DC electrical system via the cigarette lighter socket. While they offer instant gratification and are perfect for laptops, small lights, and tools, their DC sockets often have poor contact, leading to voltage drop issues.
• Permanent-Mount Inverters: These inverters are hardwired directly to the battery bank and are ideal for 400 watts or higher power requirements. They usually have built-in receptacles for appliances but do not integrate with existing AC wiring. More expensive models may include transfer switches for full AC wiring integration.
• Inverter/Chargers: These combine the functions of an inverter and a battery charger, providing outputs similar to small generators (2000-4000 watts). They feature automatic transfer switches, allowing them to shift between inverting and charging modes seamlessly. Inverter/chargers should be professionally installed due to high amp draws and potential fire hazards.
• Modified Sine Wave (MSW) Inverters: MSW inverters are the most popular type and are generally more affordable. They work well with common appliances but may not be suitable for sensitive electronics. MSW inverters can cause harmonic distortion, affecting some electronic circuits.
• Pure Sine Wave (PSW) Inverters: PSW inverters are more expensive but offer superior performance. They can run all AC loads and are ideal for stereos, computers, and sensitive electronics. PSW inverters produce high-quality AC power with minimal harmonic distortion, eliminating static lines in televisions and improving sound systems.
• Remote-Controlled Inverters: These inverters come with remote panels, allowing you to control, monitor, and program them from a distance. This feature is especially useful when the inverter is installed in a hard-to-reach place.
• High-Surge Capability Inverters: These inverters are designed to handle the high power demands of appliances during startup. They ensure that appliances with high surge requirements can be operated without issues.
• Low Electrical Interference Inverters: High-frequency inverters can cause electromagnetic interference (EMI) with SSB, Ham reception, and weather fax reception. Newer true sine wave inverter designs meet FCC Class A requirements, significantly reducing EMI issues.

Inverter efficiency

When considering inverter efficiency, it is important to understand the energy losses that occur during the inversion process. Inverters are not 100% efficient, and some energy is lost as heat during the conversion of DC power from batteries to AC power for appliances. This heat generation can impact the overall efficiency of the inverter and should be considered when installing one on your boat.

To improve inverter efficiency, it is crucial to select an appropriate inverter size for your specific needs. Oversized inverters can lead to reduced efficiency, as they will draw more power from the batteries than necessary. Therefore, it is recommended to calculate the total power requirements of the appliances you intend to run simultaneously and choose an inverter with a suitable wattage rating. Additionally, the length of the cables connecting the inverter to the batteries and appliances should be considered. Longer cables may result in voltage drops, reducing efficiency.

Inverters with higher efficiency ratings tend to be more expensive, so it is essential to strike a balance between cost and efficiency. It is also worth noting that the efficiency of an inverter can vary depending on the load. Some inverters may have a higher efficiency rating at lower loads, while others may perform better at higher loads. Therefore, it is important to consider your typical load requirements when selecting an inverter.

Additionally, the type of inverter can impact efficiency. Pure sine wave inverters tend to be more efficient than modified sine wave inverters, especially when running sensitive electronic equipment. Modified sine wave inverters may not be suitable for certain appliances and can cause them to use more power, reducing overall efficiency.

To maximise inverter efficiency, it is recommended to use appliances with lower power requirements whenever possible. This can help reduce the overall power draw from the batteries, improving efficiency and prolonging battery life. Additionally, regular maintenance and proper installation of the inverter are crucial for optimal efficiency.

By considering these factors and selecting an appropriately sized inverter, using efficient appliances, and maintaining the system, you can improve the efficiency of your inverter setup on your boat.

Frequently asked questions