Does a Boat Motor Charge the Battery?

Does a Boat Motor Charge the Battery?

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Does a Boat Motor Charge the Battery?

A Boat motor is a device that converts chemical energy from the combustion of fossil fuels to generate mechanical work.

Boat motors operate much like car motors, with a few key differences. Most boats use gasoline engines, while cars typically use petroleum diesel or natural gas.

Yes! Most current outboard motors that have an electric start will definitely have an alternator which will charge your starting battery if the motor is running. For example, if you were to charge your battery with an 80-amp charger and run an 80-amp motor into the same circuit, you would reduce the voltage by 10%.

This is because you should allow each power amp to pull a certain number of amps from your battery before you push too much amperage.

If you have enough voltage to start the motor, you are ready to go. You may notice that the battery will die quicker if you are trying to run a motor and charge the battery at the same time.

In this case, I suggest charging first to ensure enough charge in your battery for running the boat in the water.

If you use a battery charger, you must turn it off before starting the boat. Even if the motor does not start, this can damage your battery and charger. Also, unplug the charger before removing it from the circuit.

If you are burning the motor while your battery is charging, there may be an engine or fuel line issue.

This is because if these items were to malfunction, it would be much easier for you to pull too many Amps from your battery instead of them leaking out.

Do All Outboard Motors Charge Batteries?

Most outboard motors in boats, jet skis, and so on will charge their battery while plugging into shore power.

Although you shouldn’t depend on this as your primary power source, you can charge your batteries if the motor can do so when plugged in.

You won’t be able to plug it into a charger unless the motor has one built-in.

If the motor doesn’t have onboard charging features and you have outboard battery chargers available, then these devices will use AC from shore power to charge your batteries.

Automobiles, which you’ll also find in boats, work a little differently. Although you can use the alternator in an automobile for charging batteries, it cannot charge batteries as quickly as shore power.

You will have to plug into shore power if you want to recharge your battery in an automobile.

Commercial outboard motors may have “fake” onboard chargers that don’t function properly or have onboard chargers that are not fast enough to use for charging the battery.

The fake onboard chargers can often accept power from shore power and provide back-to-shore power.

The onboard chargers can only charge the batteries if they have voltage and current outputs that match what’s needed to charge the batteries.

They cannot charge your batteries from shore power if they don’t have these capabilities.

How To Know If Your Outboard Motor Is Charging Your Battery?

You need to know if your outboard motor is charging your battery, so here’s how to tell.

First, steer the boat away from shore and pull the starter cord on the engine. Check to see if it starts; if it does not, you’ll need to recharge your battery before using it again.

Next, check for any signs of corrosion on the terminals of your battery – this will indicate a leak in the system or faulty wiring elsewhere in the boat.

If you can’t find any signs of corrosion, you will need to take the boat to a marine service center and have them check your battery for proper charge.

If you are still determining what your battery can do, read my article on knowing if your battery is dead.

While you’re at the marine service center, you should also ask them to tell you how long your battery should last and what its capacity is (how much power it can store).

Knowing this information is necessary to tell if your system is working correctly. Before buying a new battery, check it with a multi-meter – this will tell you the state of the charge inside your battery.

How To Know If Your Outboard Has an Alternator?

What to checkDescription
Check The Voltage– Use a voltmeter to measure across the leads of the battery terminals to the engine circuit
Check The Voltage– Ensure the voltage is above 13.8v (a 75-amp alternator has a voltage range of 14 to 18 volts)
Check Belt Tension at Idler Pulleys– Open the lift-gate and disconnect the belt from the pulleys on both ends of the belt;

Go to step 3 if this does not result in a loose belt or slipping pulleys
Check For Belt Fraying– If the belt has frayed in the past, it is unlikely to withstand the tension at the pulleys.
Check For Loose or Worn Belt– Inspect the belt for any wear or damage and install it properly on the pulleys.
Check To See Whether or Not Your Engine Is Being Driven by A Belt-Driven Alternator – If the alternator comes up as a separate item in your wiring diagrams, it should tell you this.
Check To See If the Alternator Has an Auxiliary Belt– If it does not have an auxiliary belt, the alternator is belt-driven.
Check For Open/Closed Circuits at The Idler Pulley– This is not a good sign, as it indicates that there may be a problem with the belt tension or voltage.

Does The Idling Outboard Charge Battery?

Yes! If you have an idling outboard battery in a boat, it will charge from the alternator’s output. The amount of charge it can hold is dependent on several factors, such as:

1. Battery Size

The size of the battery will affect its ability to hold a charge. A larger battery can hold more charge than a smaller one.

And since charging depends on the current the alternator produces, it is evident that a larger battery can hold more charge.

2. Age of Battery

The age of the battery will also affect its ability to hold a charge. As a battery gets older, it loses capacity.

3. Type of Battery

Different types of batteries have different capabilities for holding charge. For example, lead acid batteries have higher capacities than AGM batteries.

This is due to the type of electrolyte that makes up the cells within the battery.

4. Temperature of The Battery

The higher the temperature, the less the battery can hold a charge. If the battery is too cold, it will not store any charge. It will lose its ability to hold a charge if it’s too hot.

Can One Trickle Charge A Deep Cycle Battery?

A good rule of thumb when charging your outboard battery is: Use trickle charging whenever possible and ensure that you monitor the voltage carefully.

If you suspect that the battery may not hold a charge, you can prevent it from losing its ability to hold a charge by keeping it in a cooler environment.

In that case, it’s better to let the battery discharge by running your boat in a sheltered area and keeping it at an even lower temperature.

Does An Outboard Motor Have a Stator?

Yes! An outboard motor, also known as a stern drive, has a stator on the propeller shaft that supplies energy to the ignition system.

Common examples of outboard motors are for boats and jet skis, though some models have attached propane tanks, which you can use for snowmobiles, RVs, and airplanes, among other vehicles.

The stator is inbuilt into the ignition system, which you usually locate in the front of the engine. The ignition system consists of a battery, magneto, spark plug, and points.

A rotating armature turns an electrical current into magnetic field energy and powers the spark plug that ignites the fuel in the cylinder to fire each time you engage the throttle.

The rotation of the shaft in the stator provides energy to light the spark plug and energize fuel, allowing the engine to operate.

The stator in an outboard motor is usually in the form of a small bell-shaped aluminum or steel disc connected to the shaft.

The rotor that provides mechanical energy comprises small magnets or permanent magnets, which you’ll find embedded into a plastic material.

The magnetic field from the stator provides energy to rotate the rotor to power the boat.

Different types of outboard motors use different components, hence their names.

What Causes No Spark on The Outboard?

Faulty CDI unit– A Faulty CDI unit can prevent the spark inside a fuel-injected engine from igniting the air and fuel mixture.
Faulty Spark Plug– A defective spark plug may not create a reliable, high-voltage electric spark that you need to light the gas in the cylinder.
Faulty Ignition Coil or Distributor Cap– If the ignition coil or distributor cap has an open or short circuit, it will prevent your engine from running properly and cause no spark on the outboard to occur.
Faulty Ignition Module– If you install the ignition module improperly or mis-connect it, it may prevent your outboard from starting properly and spark the outboard from occurring.
Faulty Spark Plugs– A defective spark plug will not create the reliable, high-voltage electric spark you need to light the gas in the cylinder.
Faulty Wiring in the Ignition System– Corroded, contaminated, or faulty wiring can often prevent your outboard from starting correctly.
Faulty Fuel Pump and Carburetor– If the fuel pump and carburetor are not operating correctly, they may prevent your engine from running properly and cause a spark on an outboard.
Faulty Battery– An incorrect battery setting can prevent the engine from starting properly.

Does the Horse Power Matter?

Yes! The boat’s horsepower matters because big motorboats have to have lots of power. The bigger the boat and the faster it goes, the more horsepower it requires.

You can determine the maximum horsepower for a boat by its length.

Keep in mind that not all boats need a lot of power, as some boats are for cruising as opposed to speed, and big boats can use smaller motors that provide less horsepower than what they call for by the guidebooks.

You should know that big boats should go fast. So, if you want a boat that can go fast and you’ve got the money to spend, get one with lots of horsepower’s.

Can One Trickle Charge A Deep Cycle Battery?

More significant engines also mean more gas consumption and more cost in gallons of fuel.

The motor provides the force to move all the boat accessories, such as the water pump, bilge pump, lights, and running lights.

This is why it’s essential to get a boat with enough horsepower for its size.

Some ratings for boats are about 60% of their actual power, so before you buy a boat, it’s wise to research and find out what kind of motor you need and how much power it should have.

What’s the Difference Between an Alternator & Stator?

Magnet– Alternator uses an electromagnet to generate electricity and then converts it to DCStators use a permanent magnet
Electrical Connections– Alternators connect the AC from the generator to the DC from the battery first and then send it out.– Stators connect the AC from the generator to the DC sent directly to the battery.
Rotating partThe rotational shaft of an alternator rotates in a circular motion, like a fan.

– A very high percentage of an alternator’s energy converts into heat
The rotational shaft of a stator doesn’t rotate in a circular motion.

– In a stator, only a tiny amount of its energy gets lost as heat.
Number of Stator PolesAlternators have two such poles, the primary and secondary; it’s the same for each side.

You can use the secondary pole to create a voltage that you can use for lights or devices that need electrical power.

A generator can have four poles; this depends on the generator’s voltage; the bigger it is, the more poles it has.
How can you convert electricity into mechanical energyYou can convert electricity into mechanical energy by a rotating armature in an alternator, for example, in a cars or an engine’s alternator.With a stator, this conversion occurs through electromagnetic induction.

How to Properly Wire & Use a Battery Selector Switch

Start by turning off power to the off-grid battery bank by flipping the main panel circuit breaker switch to OFF.

The battery selector switch is one of those investments that can make or break an off-grid system and is essential for safe, reliable operation in case there’s a problem with your solar panels or wind turbine.

There are two types: Manual (requires manual intervention) and automatic (switches power on/off automatically).

The disadvantage of the automatic battery selector switch is that there can be a 30-second delay before power automatically switches on when the PV array starts producing power.

The advantage of an automatic selector is that it doesn’t require your fingertips to press each button individually.

Still, you’ll have to remember which button you’re using and miss out on the benefit of using solar energy to charge your batteries overnight.

A manual battery selector switch has buttons for each battery bank, so you press a button to select the bank you want to charge.

Can One Trickle Charge A Deep Cycle Battery?

The advantage of using a manual battery selector switch is that it’s possible to keep your batteries fully charged overnight by pressing one button.

The disadvantage of using a manual switch is that it requires your fingertips to press each button individually unless you have an automated way to activate the proper switches at night.


The essential part of a boat is the motor engine; when working properly, it gives off the power that makes the boat move.

Tragedies can occur if you need more engine horsepower to get to where you need to go safely or when trying to stay on top of the water.

Remember to get a good motor and be sure it’s running using tools like a Battery Selector Switch.


Hi! I' am Tom. I was a manager in one of the biggest stores for over 10 Years, am also an SEO by night. I don't like to call myself a blogger; they are very analytical, do email marketing, and know all SEO stuff. I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

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