UniEnergy Technologies Battery » Charging Trolling Motor Battery With Solar (3 Easy Steps & Benefits)

Charging Trolling Motor Battery With Solar (3 Easy Steps & Benefits)

With the advent of solar panels, it is little wonder that many people are going off the grid. You will find that solar works for almost everything for which you need electricity or a battery charge. So, it is not strange to find fishermen and anglers asking if solar can charge their trolling batteries.

You must understand the power needs of your trolling motor battery before determining whether or not solar can charge it. And by solar, we must assume you will use solar panels because they are the most portable and accessible means of getting solar power.

Determining the Solar Power Output for the Battery

There are several types of solar panels for charging a trolling motor battery or other marine batteries. But before you decide which works best for your rig, check the battery capacity and ensure it is charged to lower the energy requirements.

So, what are the power needs of your trolling motor? Since it is trolling, it means the motor is not in use. Therefore, there is no heavy energy load on the solar panels. If the battery is fully charged, you will not need more than a 10-watt solar panel to keep it from discharging. At most, you will need a 12-watt panel.

However, if the battery has partially discharged and you need solar power to charge it while trolling, you will need more efficient and heavier panels. To determine the best solar power output to charge it fully, you need the battery size and power requirements.

Solar Panel By Size and Capacity

If your battery is full, a 10W or 12W solar panel should provide enough energy trickle to keep it from discharging. But if the battery is significantly depleted, the size and type of battery will determine the required solar panel size and capacity.

For example, a trolling motor battery with a capacity of 100ah will need a 12V 100W solar panel to recharge. This solar panel typically produces about 30A of energy, which means the charging time will take about two days, depending on the battery’s depth of discharge. 

The recharge may take about three days if it is more than 50% depleted. Note that the higher the battery voltage requirements, the higher the required solar panel output. So, 24V batteries require a larger panel with the requisite energy output.

Operating the Battery on Solar Power

Since it is difficult to recharge a depleted trolling motor battery with solar, it is more challenging to operate it on solar. It is not impossible, but it will require a lot of energy output to achieve. The battery capacity will determine the required output, but the larger the battery is, the more solar power it will need. 

Consider a solar generator if your boat is too small to accommodate heavy or large panels. It typically requires less space than solar panels but may generate more power.

Recharging Your Trolling Motor Battery with Solar – Steps

Recharging Your Trolling Motor Battery with Solar Steps

Recharging your trolling motor battery with solar panels is straightforward as long as you have everything you need. The following are the steps to charge the battery with solar panels.

Step One

The first step is to ensure the solar panels are in the right position to get the most sunlight. There are specific times of the day when the sun is at its peak, and solar panels perform best at these times. 

If you know beforehand that you will use these panels for the trolling motor battery, set them to absorb as much sunlight as possible. Then, they can store them for later use. 

Also, find the best orientation and slant for the panels for the best results. Having maximum sunlight is not the only consideration. You must set the panels to face the right direction and have the correct slant for maximum sunlight absorption.

Step Two

The next step is disconnecting the battery from the trolling motor and connecting it to the solar battery charger. Ensure the motor is no longer running before disconnecting the battery. The solar panel for charging the battery should come with an attached charger, which you connect to the battery. 

Ensure you make the correct connection. The black wire should go to the black wire on the battery and plug the battery’s red wire into the red one on the charger. Do the same for the positive terminal and negative terminal when fixing them to the connectors.

Step Three

The final step is to turn on the solar charger to begin the process. You should find a power switch to turn the charger on and off. Note that the charging process typically takes a long time. It may last longer than the usual board or portable charger. 

Therefore, expect it to last several hours. This is especially true if the remaining battery charge is less than 50%. However, you must keep an eye on the battery and charger throughout the process. Never leave it unmonitored for an extended period.

Factors to Consider

Factors to Consider

While there are specially-designed solar panels for charging trolling motor batteries and others like them, the usual solar panel should do the job. In other words, you only need a good-sized and efficient panel for your battery.

1. Size

However, you must consider the size of your boat before mounting the panel. A typical trolling boat is small and can only accommodate a small panel. So, if your battery needs a long charge, a small panel may be insufficient to do the job, and your boat may not accommodate a bigger panel.

2. Depth of Discharge

The space issue brings us to another important factor: the depth of discharge. Trolling motors usually use lead acid or AGM, and both work with a 50% depth of discharge. A battery’s depth of discharge, DOD for short, is the depth to which it drops before critically requiring a recharge. In other words, a battery with a 50% DOD must be charged at 50%.

The battery’s DOD will determine the type and size of solar panel sufficient to charge it. The lower the battery level, the larger the panel must be to complete the recharge. Otherwise, the solar panel may not fully charge the battery or take too long to charge.

3. Charging Time

Another factor is the charging time. While it does not seem a serious issue and is not in many cases, you must consider the length of charging time for a few reasons. The longer the battery charges, the higher the risk of battery sulfation. Sulfation can prematurely damage the battery beyond repair. 

It would help if you also considered the charging area and potential emergencies. If the boat is out in the open during the charge, the weather may change, and sudden rain will affect it. Additionally, needing the boat during the charging time truncates it, and the battery may not run.

Benefits of Charging a Trolling Motor Battery with Solar

Benefits of Charging a Trolling Motor Battery with Solar

You never know when you will run out of battery power while trolling. It may seem like there are too many downsides to solar-charging the battery, and it is not worth the risk. But the perks are excellent and may make you forget the possible cons.

1. Safety

All you need are the photovoltaic modules; the inverter is unnecessary. The solar charger does not come with moving parts that may wear or break down. All that may be required is to protect the solar panel when you are not using it.

2. Eco-Friendliness

Another perk of using solar panels to charge your trolling motor battery is a lack of carbon footprint. Solar panels leave little to no carbon footprint because they produce renewable energy, so they do not generate emissions that hurt the environment. They are also easy to dispose of if you dump them in regulated recycling sites.

3. Energy Supply

There is no limit to how much energy you can generate with solar power. All you need is adequate sunlight, the right panels, proper orientation, slant, and location. As with other recharging methods, you never have to worry about running out of gas or fuel. 

Best of all, you are not paying to get the energy supply; the only payment is for the solar panel during the initial purchase. With warranties between seven and ten years for most solar panels, you will get your money’s worth in no time because of their durability.

4. Convenience

Solar panels are easy to carry and connect with the appropriate instructions, making them a convenient battery charging method. The same applies to a solar generator. Most solar charging equipment will fit into small boats unless they are too heavy. In addition, the connection is easy; you only need to connect the battery to the charger. The rest is up to the sun and the panels.


The energy capacity of a boat is high, regardless of the size. Most trolling motors require powerful batteries for the work they have to do. Consequently, boat owners and renters seek more affordable alternatives for powering them. Therefore, there is a rise in the demand for solar for charging trolling motor batteries. 

However, you must know the battery capacity, usual run time, and discharge level before choosing a solar power system for recharging it. Fortunately, there is always an option for all battery sizes, so consider solar panels or generators.

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