How to Connect Three Batteries to a Boat

January 5, 2021 9:15 pm Published by Leave your thoughts

Having backup batteries available on your boat is important—but how do you connect and switch between them? Generally, you don’t want to drain power from more than one battery at once, depending on what they’re connected to and how long you’ll use them. Therefore, you’ll need to use a battery switch. Here’s how to connect three batteries to a boat in Houston, TX, and how to use the battery switch to select your power source.

What is a battery switch and why would I need one?

Battery switches allow you to choose which battery you’re using, which comes in handy when you’re only running the engine or the on-board systems at any given time. Boats with more than one battery typically have an engine battery and a “house” battery for the on-board systems. In fact, your boat might have three batteries, depending on how many engines are installed or how serious you are about backup power.

The reason for having multiple batteries is to ensure that even if you drain your house battery, you’ll still have enough power to start your engine and get the boat back to port. With a battery switch, you can keep the power sources separate and monitor usage.

What kind of battery switch do I need?

Getting the right kind of switch is important. You can cause major damage to engine electrical systems on some engines if a battery is disconnected while the engine is operating. The switch should match the amount of current and amperage to operate efficiently. Keep in mind that some switches are rated for different size batteries and engines, so make sure you know what kind of batteries and engine your boat uses.

So how do you know which switch to buy? Protection guides tell us that regulations require a cut-off for batteries rating above 800 CCA. Another recommendation is when the alternator needs to be protected when a switch is involved. These switches are called AFD switches, which stands for “alternator field disconnect.” Your alternator is used to charge batteries while the engine is running, and a battery switch can help you choose which bank to charge. The switch protects the alternator from voltage spikes. However, if you have a boat with a battery isolator, your alternator is already permanently connected to the batteries—you don’t need a special AFD switch.

Ask an expert

If you’re still unsure about what kind of battery switch you should use, don’t hesitate to ask one of the experts at Texford Battery Co. Our staff is well versed in how batteries and battery switches work—just bring in your old batteries and boat engine information so we can help you find the right solution for your boat. With 90 years of experience, our team is sure to be able to explain what you need and why, no matter what kind of boat you have. Call or stop by today to learn more about what switches are required for boats with three batteries in Houston, TX.

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