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How to Charge a Boat Battery on the Water? – A Complete Guide

Written by Anthony Roberts / Fact checked by Jonathan Larson

how to charge a boat battery on the water

Traveling by boat is such a fun and relaxing activity, especially in this hot summer weather.

However, there are certain things needed to prepare for a boat ride, and one of them is a battery. Thanks to the advancement of technology, multi-purpose batteries specialized for boats are becoming more popular in many stores.

Nevertheless, it is not pleasant to have our boat’s batteries run out of charge and leave us stuck in the middle of nowhere. Therefore, you as the sailor must understand ways of charging batteries or some skills to deal with these situations.

Today, in this article, I will show you useful guidelines on how to charge a boat battery on the water and other tips with different trolling motors in real life.

In short, there are steps that you can take to charge a boat battery with a charger or without a charger. We will also take you through the different types of batteries to help you avoid losing a fun boat trip and charge your boat in different and creative ways with just minimum effort needed. Therefore, stay tuned!


Charging a Boat Battery with a Charger


In the most ideal circumstance, when our boat has been charged fully, we can concentrate on the fun; without worrying about running out of battery. Even so, having a charger on board is still very important, and choosing the right charger for your boat is also necessary.

1. Types of boat battery chargers

Similar to the variety of boat batteries available in the market, there is also a wide range of charging products for boat batteries to choose from. Still, you can divide all chargers into two categories: portable and on-board.

Living up to their name, portable chargers are famous for their portability and ability to be used in many situations, including in the waters. They are considerably less expensive than an on-board charger. However, the slow charging pace is a huge disadvantage of these chargers.

Meanwhile, as they are always connected to the battery system, on-board chargers are easier to utilize. All you have to do is to attach them to a standard 120-volt outlet. Fast charging is possible with these, but they are less affordable than portable ones.

2. How to charge a boat battery with a charger

There are two ways to charge a battery inside a boat. The conventional method is to use an electrical charger with support from a 120V outlet, while Solar-powered chargers are more innovative and environmentally friendly. Let’s have a quick look at both methods.

Before charging your boat with a traditional charger, you need to get a charger of any kind that can draw power from the 120V socket of your vessel. It is crucial for both ways of charging.

If you use a portable charger, you have to connect the positive and negative cables to the battery’s terminals for charging. Now, you should plug the power drawing wire into a 120V socket. Turn on the outlet, and you’re done! Your battery will automatically charge.

On the other hand, solar chargers may be a very cost-effective solution that provides a continuous supply of power to your battery. These pieces of equipment act like power maintainers rather than chargers due to their finite resources.

To utilize solar chargers, you have to install the solar panel on your craft’s roof. The 12V DC electricity must then be converted to 110V AC using an inverter. You may then use it to recharge your battery, although the price for panels and an inverter is quite high.

Charging a Boat Battery Without a Charger


The ideal boat cruise may sound feasible, but it does not work all the time. The worst-case scenario can always happen to us. We hop in our boat, turn on the key, and ride normally before the engine makes sluggish sounds, then dies in the middle of nowhere. Why?

While there are many reasons for this incident, the battery is the most common. The battery may be dead or out of energy as you forget to charge it. No matter what caused it, don’t panic! There are ways you can deal with this battery on your own before calling for help.

Jump-starting a dead boat battery is the most simple solution. All you need is a set of jumper wires and a working battery. However, having a jump starter will make things a lot easier. There are few ways to deal with dead boat battery using a jump-starter:

1. Using a backup battery to jump-start your boat

To create a temporary power source, connect the black jumper wire to the dead battery and the good battery’s negative terminals. Then, repeat this process with the red jumper wire until there are positive terminals of both the good and dead batteries.

If the spare battery works perfectly, it will instantly start the dead battery. When the boat runs, you may immediately remove the jumper wires as the alternator will charge the battery ever since then.

2. Starting your boat directly by a Jump-starter

This is probably the easiest and most convenient way to deal with a dead-boat battery. Jump-starters are battery-powered devices used to jumpstart boats and other vehicles. They work similarly to jumper wires and don’t require a second vehicle to deliver the power.

To connect the jump starter with the battery, attach the black wire from the jump starter to the dead battery’s negative terminal and the red cable to the dead battery’s positive terminal. As soon as the boat starts, remove the wires.

These are some methods that you can use to provide power for your battery without needing chargers. However, in any case, I still suggest having a spare battery and calling for help if it is necessary.

Charging Trolling Motor Batteries While on the Lake

Trolling motor batteries are the same as many types of boat batteries. So, the charging methods are technically similar. When using solar panels, onboard chargers, or trickle chargers, it is possible to supply power for trolling motor batteries.

On the other hand, you can use the outboard motor available on your boat to charge the battery directly. Although you will have to figure out ways to connect, keep reading as I will provide detailed tutorials below!

The first way to use your outboard motor is to install a regulator on the motor. Then, attach the positive and negative wires to the matching ones inside a cable. The cable will then run from the outboard engine to the battery and can be used to hook into the battery.

Using a battery combiner is another simpler option. This device works as jumper cables allow your motor battery to share a charge with another one. To put the combiner in, you need to hook the red lines to each battery’s positive terminals and vice versa with the black lines.


Dealing with a dead boat battery is such an unpleasant experience. However, by following these tips, you can easily handle the situation and get back to the fun. Still, my best advice is to have a backup battery or a portable charger for emergencies like Marine Battery Charger.

Did you enjoy the article on how to charge a boat battery on the water? Do you want to add anything else? Please let me know and leave a comment below.

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