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How to Attach a Circuit Breaker To a Marine Battery?

to attach a circuit breaker to a marine battery

If you know anything about electricity, then you probably know that circuit breakers are an essential safety component to any electrical system.

But what about electrical systems generated by batteries?

Specifically, do you need a circuit breaker for the marine battery on your boat? How do circuit breakers work with marine batteries, and how do you install them?

Keep reading!

In this article, you’ll learn what you need to know about how to attach a circuit breaker to a marine battery and why this is an important safety step when setting up your boat’s electrical system.

Ready to dive in?

What Is a Marine Battery Circuit Breaker?

T Tocas 50 A Circuit Breaker amp Breakers with Switch Manual Reset

Simply put, a marine battery circuit breaker is any circuit breaker made for use with marine batteries and in marine settings.

Functionally, it works the same as any other type of circuit breaker, though it will also be waterproof and specifically designed for outdoor use. 

A marine battery circuit breaker looks like a little box, typically small enough to fit comfortably in your hand. Like other types of circuit breakers, it is designed to break up the flow of current from your battery for safety reasons.

If something hooked up to your marine battery is drawing too much current, this extra rush of heat and electricity can cause a fire, or it may melt or cause other damage to equipment. The purpose of your circuit breaker is to disrupt this excess current, causing the power flow to fail.

Circuit breakers are primarily intended to open when there is an overflow of current, but before the current gets hot enough to damage wiring or equipment.

Fuses work in a similar way, but they are destroyed every time they blow, so they have to be replaced. When a circuit breaker is tripped, it simply has a switch flipped and needs to be reset — some even reset themselves automatically.

Circuit breakers can be used again and again.

A marine battery circuit breaker is installed on the wiring of a marine battery. It protects the battery and any equipment running off the battery by ensuring that nothing overdraws the battery or short circuits.

For example, if you’re operating a trolling motor and a fishfinder off your battery, and your trolling motor is set at maximum power during hazardous weather conditions, the battery may become overworked, and the trolling motor may overdraw the battery.

If you have a circuit breaker , it will break the current flow, killing power temporarily but preventing damage to the battery and trolling motor. 

You can, of course, reset the circuit breaker so that current flow will be restored; and in this case, it would be best to set the trolling motor at a lower power setting or turn off the fishfinder to prevent further issues.

How Does a Marine Battery Circuit Breaker Work?

How a Circuit Breaker Works in Slow Motion - Warped Perception - 4K

Marine battery circuit breakers work like any other type of circuit breaker — by disrupting the flow of current in an electrical circuit when the current becomes too hot or too strong for the cords and devices it is passing through.

Marine battery circuit breakers look like small electronic boxes with plugs, switches, and terminals. The terminals can be connected via battery cables to your marine battery. 

When current passes through the electrical circuit of the battery and devices, it will also pass through the circuit breaker. The circuit breaker will be set to open when it senses that a certain amp capacity has been reached.

Circuit breakers are rated for different amp capacities. Above the rated amp capacity, the circuit breaker will open — literally breaking the electrical circuit. 

This prevents the wires and other components of the circuit from overheating, melting, and potentially causing a fire.

It’s important to find out the appropriate amp capacity for your boat, battery, and all devices hooked up to the battery. Your circuit breaker will need to allow the proper amount of current to pass through without allowing anything to become overheated or overwhelmed with the current.

For more detailed information on how circuit breakers work in general, check out this article from HowStuffWorks.

How Do You Attach a Circuit Breaker to a Marine Battery?

Putting a circuit breaker on your marine battery is a fairly simple process.

If you haven’t done a lot of wiring before, it may be a good idea to check out a tutorial video like the following one to get a good visual before starting:

Bass Boat 30 Amp Circuit Breaker Replacement

Then, follow the steps below:

  1. Find a spot on your boat to mount the circuit breaker. It should be somewhere near the battery, perhaps on the side of the battery compartment. Though it should be rated for marine use, it is still a good idea to place it in a sheltered spot if possible.
  2. Screw the circuit breaker directly onto the boat, or onto a mount, in your desired spot. The circuit breaker should have easily recognizable screw holes, and many will also have the necessary hardware.
    It’s best to use a power drill for this step, as it will be much easier and quicker than screwing the breaker in place by hand.
  3. Connect the battery to the circuit breaker using battery cables. You’ll want to use cables with ring terminals on both ends. Connect one end of the red cable to the positive battery terminal and the other end to the positive terminal on the circuit breaker.
    Repeat this step with the black cable, attaching one end to the battery’s negative terminal and the other end to the circuit breaker’s negative terminal.
  4. Make sure the circuit breaker is set to the “on” position. If it is set to “off,” then no current will be able to pass through the breaker. Make sure it is on, then test any of the devices hooked up to the battery to make sure you have power.
  5. Reset to the “on” position whenever the circuit breaker is tripped. If your circuit breaker resets automatically, you won’t have to worry about this step. Otherwise, you will need to remember to reset your circuit breaker manually each time it blows.


If you have marine batteries on your boat, then attaching circuit breakers to them is an important safety measure. These small electrical boxes can prevent major electrical problems such as fires, overheating wires, and other damage to devices.

Mounting a circuit breaker on your battery is fairly easy. If you’ve never done it before, check out the video and follow the steps outlined above.

With any luck, you’ll have the breaker installed in no time so that you can get back out on the water!