does my boat motor charge my battery

Does My Boat Charge My Battery? – [Problem Solved]


Ran out of battery in the middle of nowhere? Well, in situations such as this, we desperately look for alternatives to charge our batteries. Charging the batteries through the boat does not seem like a distant idea at that time. 

So, the big question is, does my boat charge my batteries? 

To answer your question, Yes, your boat can charge your batteries. But you will need to have the outboard running for that. The alternator will take the responsibility to recharge the battery if the outboard is running. This will happen to compensate for the power used for starting the motor.

Sounds relaxing? We have got an elaborated version of this down below. If you want a full demonstration of your query then don’t wait. 

Join us and have a brief knowledge of how the boat charges batteries. 

How Do Outboards Charge Batteries? 

Whether the outboard charges the batteries is among the most concern. Although it does charge the batteries, it depends on some variables. 

Such as the types of outboard you are using. A two-stroke engine charges the batteries differently than a four-stroke engine. 

Some boats contain charging circuits. They use an alternator to charge both the in-house and starting batteries. Johnson outboard charging is an example. Here, both of the batteries charge at the same time. Therefore, it is much more efficient. 

Using a solar panel for charging purposes is also an efficient method to charge the batteries. But the tradeoff of using solar panels is that it is quite expensive. Also, it is heavily reliant on the weather as well. So, it will not be able to provide service at all times. 

Procedures for Charging with An Outboard Motor

As we mentioned earlier, solar panels bring efficiency. But the unreliability of it makes the outboard take the helms. 

But there are some components needed for the outboard motor to charge the batteries. Those being; 

  • An electrical generator with a coil. The electricity is produced as the generator rotates the motors. 
  • A regulator or rectifier. A regulator converts the pulsating waves of the AC current into a constant direct current. This procedure is suitable for batteries. 

Once you can gather all the necessary tools, it’s a 10 minutes task for you. 

Mount your heavy-duty waterproof connector in the hull. Therefore, the disconnection and reconnection process will become much easier for you. Also, you are not required to do any drilling which are unnecessary. . 

Then, put together a 2-wire harness. Preferably out of 12 AWG cables. Insert one end of it to the rectifier or the regulator output. And insert the other one to the grounds on the motor. 

The exit of the cable is through the accessible grommet at the front. Before it terminates in a male half of a two-pole connector. 

Thirdly, take a 12 gauge duplex cable and run it from the motor to where electricity is required. Attach one side of the outboard connector. 

Finally, attach a 10 amp fuse holder to one end of the positive cable. The positive side of the battery’s terminal needs to be connected with the positive side of the cable. . 

On the other hand, the negative side of the cable is connected to the bus bar where other wires are connected. 

Instructions to Charge Trolling Batteries from Outboard Engine

To charge the batteries through the outboard motor, you need to follow some procedures as well. Those being; 

Step 1

At first, the battery combiner needs to be mounted within two feet of the starting battery. Usually, the combiners come as waterproof. 

Therefore, they are not required to be undercover. Also, the LED helps with the visibility while exposed to direct sunlight. 

Step 2 

Identify the red cable. Then connect it with the starting battery’s positive side of the terminal. Both leads of the cable can be interchangeably used with a 100 amp connector. 

Step 3 

The third step would be to connect the other red end to the troll battery’s positive terminal. Use an extension cable if you want it to mount to the bow. 

Subsequently, all the negative ends need to be connected together through a duplex wire. A 12 gauge duplex wire would be the best one to use for this job

Ensure to leave enough space so that nothing remains short. 

Step 4

Now connect the negative terminals to both batteries. As a result, the path for returning charging currents will be created. 

Ensure that your cables don’t suffer any damage. Otherwise, you will face major consequences. Especially if your boat is made of metal. 

Step 5 

Now connect the black terminal lead to the negative lead of your starting batteries. Use a shortened cable. But don’t short too much that it disrupts your connection. 

Step 6 

Finally cut 2 or 3 inches of green wire and wrap it with electrical tape. Ensure that it is completely restricted from any sort of contact. 

Well, if you are confused about which electrical tape to choose, have a look below!

Product 1
Product 2

I hope these suggestions were useful.

These are the steps that you need to follow in order to set your outboard motor. So, it can charge your batteries. 

How Long Does It Take for an OutBoard to Charge a Battery? 

How well the outboard motor performs in terms of charging batteries depends on other sources of the boat. Generally, the power consumption of other sources determines how fast your batteries will be charged. 

While trolling, a battery will be charged by attaching to a shore charger. Although it is variable, at 10 amps, 1 hour of trolling is done with 2 hours of charge. 

Also, a float charger can be another option as well if you are not at the sea. As the most automatic float charger shut down once the battery reaches 100%. 

Therefore, it does not overcharge and ruins your battery. Another important thing is, that you better know how to charge your battery on water.


Will my outboard charge my battery?

Yes. Most outboard motors can charge your batteries. Even if they don’t have an electrical starter they can, the process is relatively similar to your car charging the batteries. For any large displacement outboard motor, this is a rule.

Will an outboard motor charge a deep cycle battery?

Trolling motor deep cycle batteries will not be charged by the outboard motor, most of the amps from the alternation will be required to start the engine. Therefore, there will be no residual electricity available to charge the deep cycle batteries.

Do the boat battery charge while the engine is running?

The alternator will start charging the batteries once the outboard is on. This compensates for the power which was delivered to start the motor. Also, any other power is drawn that the house needs. 


This is all from our end. I hope now you are clear about “does my motor boat charge my batteries?

Now that you are well informed on it. You can take necessary measurements in terms of charging your boat batteries. Having a properly charged battery can make your boat riding much smoother. 

So long for today. Until next time, have a lovely day!

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