How To Set Up and Wire Your Fishing Boat Batteries

Posted May 09, 2023

Learning how to wire the batteries correctly on your boat is very important if you want to understand how your boat motor, trolling motor, and electronic fishing and navigation gadgets are powered. For some, boating is a part-time activity reserved for the weekends, and for others, boating is a way of life that requires high levels of commitment. While the importance of boating to daily life varies, one thing that is similar for all boat aficionados is the increased number of tools, technologies and gadgets that are used onboard. These tools need a powerful battery that can keep up with all the demands being placed by the boat.

The Best Battery Setup For Your Boat

There are various kinds of battery setups possible for wiring your boat, including single and dual battery options. A dual battery setup is the best choice for a fishing boat as it allows for separate power sources that can give you the most efficient level of energy needed for starting the boat and operating tools you use on the boat. With the dual battery setup, one battery acts as the starter battery, which starts the engine, and a second battery is used to power all of the tools you need to have onboard like fish finders and GPS systems.

Making the Right Battery Selection

When choosing the optimal battery for your boat, a few considerations need to be factored in, including the following:

Cold Cranking Amps

Cold cranking amps (CCA) refers to the level of current that a battery can provide in a 0-degree Fahrenheit temperature for over 30 seconds. This relates to the number of amps your engine needs to get started. In order for your engine to start in harsh, cold temperatures, you need to have a cold cranking rating that exceeds your engine’s requirements. A concept related to cold cranking amps is marine cranking amps, which are used to help users understand the amps needed to power engines for boats. Knowing your engine’s cranking amp requirements is vital to making the right battery choice.

Conductor Gauge

You should also pay attention to your conductor gauge when selecting a battery, as this needs to be compatible with your battery size. If the conductor gauge and battery are not compatible, this could result in unnecessary safety hazards, as there are max amp draws associated with each gauge.

Circuit Breaker Sizing

An overcurrent protection device, such as a circuit breaker, must be used to protect the safety of your boat’s energy system. The type (e.g., voltage and current rating) of the circuit breaker must be sized in relation to the trolling motor used. This will help you avoid headaches and make sure your boat’s electrical system stays completely intact on your future boating trips.

What Tools and Supplies Will You Need?

To get started with wiring your boat, you will need to keep some basic tools on hand to help you with the process. These tools include:

  • Lithium batteries: two batteries to use for the dual battery setup
  • Cables: multiple cables to connect batteries and start bank terminals
  • Cable cutters: a pair of cutters to adjust the size of the cables being used
  • Wrench: an adjustable wrench to secure the connections
  • Grease: to use in the protection of electrical components
  • Swagging tool: to help adjust tubing fit so that it can secure brazed connections

Wiring Options: Series or Parallel?

In order to fully understand what wiring choice is ideal for you, first you need to decide if you will benefit from a series wiring option or a parallel wiring option. To know which of these is right for you, ask yourself first, what am I using the battery for? The series battery is used for high powered applications such as large boats that have high voltage. Most other situations will call for the parallel wiring option.

Series Wiring Option

High power applications like on large boats, or in scenarios with large inverters, benefit from a series wiring setup. This wiring option uses anywhere from 2 to 4 batteries, and all of the batteries being used in the series must be similar with regard to age, size, type and manufacturer. When wiring batteries in series, the voltage of the individual batteries are added together, as seen in the examples below.

  • 24 Volt: uses two 12-volt deep cycle batteries
  • 36 Volt: uses three 12-volt deep cycle batteries
  • 48 Volt: uses four 12-volt deep cycle batteries

To wire a group of batteries in series, you connect the negative terminal of one battery to the positive terminal of another battery until all of the batteries are connected. After this, you need to connect a link/cable to the negative terminal of the first battery in your string to your application. Then connect another link/cable to the positive terminal of the last battery in your string to your application. When wiring batteries in series, make sure to always use a charger that matches the battery system voltage. It is also recommended that you charge each battery individually to avoid battery imbalance.

36V Trolling Motor Series Wiring Diagram

Parallel Wiring Option

With parallel wiring, your total battery capacity increases, while the voltage remains the same. This is due to the fact that amperage increases when batteries are wired in parallel, resulting in greater battery longevity. Like the series wiring option, batteries wired in parallel also require that all the batteries in the setup are similar with regard to battery age, size, type and manufacturer.

To wire batteries in parallel, you need to run one wire from the positive terminal of one battery to the positive terminal of another battery. Then, another wire needs to be run from the negative terminal of one battery to the other. Lastly, on one battery, a lead is connected to the positive terminal and another to the negative terminal.

36V Battery Parallel Connection Boat Wiring Diagram

Need Advice on How to Wire Your Boat?

RELiON has decades of experience assisting boat aficionados with a wide range of solutions for their battery setup. If you are not sure whether you benefit best from parallel or series wiring, or which voltage battery is the right choice, you can contact a RELiON representative anytime.