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Marine Vs. Car Battery (Can You Use a Car Battery For Boat?)

Both motorized vehicles and watercraft utilize batteries to supply power to the engine’s motor. In fact, both cars and boats utilize lead-acid batteries. Given that the same type of battery is used, many people have wondered whether car batteries can be used in boats. 

Despite both using lead-acid batteries, car batteries cannot be used for boats. Car batteries are designed to supply large amounts of current in short bursts, while marine batteries are designed to supply smaller volumes of current over longer periods. These batteries are not interchangeable.

To better understand why car batteries cannot be used to power marine vehicles, it’s important to know how lead-acid batteries are used in cars and boats. Ultimately, this will explain why car and marine lead-acid batteries cannot be used interchangeably. 

Can Car Batteries Be Used For Boats?

Whether you’re on land or sea, if you’re using a motorized vehicle or vessel to get around, you’re using a battery. There’s a common misconception that these batteries are used to generate power or electricity. However, this isn’t accurate. 

Instead of generating electricity, the batteries in cars and boats are used to store electricity. The battery in your vehicle or boat will be charged while the machine is being used, with the charge being stored for use later. In fact, both cars and boats utilize lead-acid batteries, which utilize lead plates submerged in diluted sulfuric acid. 

boat battery

Due to this, many people have wondered whether the batteries typically used in vehicles can be used for boats. While vehicles and boats both utilize lead-acid batteries, they do not utilize the same size of lead-acid batteries. Of course, this means that a car battery cannot be used to power a boat. 

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The lead-acid batteries used in cars are referred to as car or starter batteries. The lead-acid batteries used by boats, on the other hand, are known as marine batteries. In terms of their design and functionality, marine batteries are a cross between automobile batteries and deep cycle batteries. 

Essentially, marine batteries feature a more complex design to the nature of marine travel. This is reflected in the starting process of marine batteries, which is higher than that of car batteries. Ultimately, the differing design, size, and functionality of the car and marine batteries are why they cannot be used interchangeably. 

Understanding Why Car Batteries Are Incompatible With Boats 

In order to understand why car batteries are incompatible with boats, you need to know what car and boat batteries are used for. This section will explain the differing functionality of lead-acid batteries used in cars and boats. 

How Lead-Acid Batteries Function In Cars 

car battery

Firstly, let’s look at how lead-acid batteries function in cars. In automobiles, the function of these batteries is rather singular. Essentially, car batteries are used to start the car, which is the reason they’re also known as starter batteries. These lead-acid batteries are used to power your car’s starter motor and ignition system. 

Of course, this functionality explains why vehicles do not start when the battery is dead. When compared to marine lead-acid batteries, car batteries utilize more lead plates. By using more lead plates, your car battery can create a large initial current, which is required to start a vehicle. Ultimately, car batteries are designed to provide that initial burst of power. 

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Generally, the energy generated by the engine is used to power the wipers, lights, GPS, and stereo while the car is in use. However, when the engine is switched off, the car battery can provide short-term power to a vehicle’s components. 

This functionality is reflected in a car’s battery’s cold-cranking amps (CCA). The cranking amps of a battery refers to the amount of power the battery can provide when starting a vehicle in regular climatic conditions. 

How Lead-Acid Batteries Function In Boats 

lead acid battery

Unlike lead-acid batteries used in cars, those used in boats do not need to provide such a large initial current. While marine batteries do supply an initial burst, they’re designed to provide a continuous energy supply to your boat’s engine. 

While car batteries release large currents in short bursts, the lead-acid batteries used in boats are designed to release smaller currents for extended periods of time. This is because your boat’s pumps, gauges, sound system, and lighting are powered by this battery. 

As we mentioned earlier, marine batteries are considered a cross between starter batteries found in cars and deep cycle batteries. For boats with GPS navigation systems, navigation lights, and other extra features, it’s often recommended that boat owners opt for full deep cycle batteries. 

Of course, this speaks to the increased dependence on the batteries used in boats. This also explains why marine batteries are far more robust than those used in cars. The sturdier structure of boat batteries allows them to skillfully handle vibrations caused by bumpy marine travel

If marine batteries weren’t designed this way, rough waters would result in the battery short-circuiting. Specialized marine batteries are used to support all the components of marine boats and their engines. By using the correct battery in a boat, owners can ensure optimal performance. 

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As we explained, car batteries will indicate cold-cranking amps (CCA), which measure how much power the battery can provide when starting a vehicle in moderate climates. Lead-acid batteries used in boats, on the other hand, feature a Marine Cranking Amps (MCA) rating. 

With cold-cranking amps, car batteries are tested below the freezing point. This is because cars can be used when temperatures are below freezing. However, marine batteries are tested at the freezing point, as boats rarely go out on icy waters. This is another core difference between the lead-acid batteries used in cars and boats. 

Conclusion

Although cars and boats both utilize lead-acid batteries, their batteries cannot be used interchangeably. Car batteries are designed to provide vehicles with large bursts of power when starting the car. Marine batteries, on the other hand, are designed to supply continuous power to boats. Due to this differing functionality, car batteries cannot be used for boats.