What Is the Difference between Marine Battery and Car Battery?

Mechanic using booster cables to start-up a car engine
Mechanic using booster cables to start-up a car engine

Batteries are important aspects of both automotive and marina uses. Most of the time there are shops around that take the guess work out of which battery is which, according to the model of our vehicle or boat, so we stay on track.
However, you may be one of those people that has always been curious about what the difference is between a marine battery and car battery.
It’s important that we are aware what batteries we are using and why. The main reason behind this is safety concerns as lack of knowledge results in unnecessary accidents.
Today, we will go deeper into the difference between these two batteries. Let’s get started!

Table of Contents

What Is the Difference Between Marine Battery and Car Battery?

It may be a surprise that in some instances these two batteries may interchangeable; however, the size may be a tad different, and there are a few variables you will have to take into consideration.
Going straight into the differences between the two batteries, we can see the following:

1. Power

In terms of voltage, the two are quite similar as both of them can produce 12 volts of power. But in terms of discharge, they differ in their supply of power.
Car batteries are designed to release a huge amount of power when starting an engine. When the engine starts, all the power used to start or to crank the engine will be replaced by the alternator.
The alternator is the engine’s power generator that supplies electrical power without using the car’s battery. While the engine is running, the alternator generates power to recharge the car’s battery and to supply it to electrical devices that are also running such as lights, horn, and other parts of the car’s electrical system.
Basically, car batteries don’t work that much when the engine is already running. It’s the alternator that works to supply power to all of the electrical components.
What car batteries really do is to start the engine only. This is why they are also called crank batteries as their ultimate purpose is to crank the engine.
On the other hand, marine batteries work differently. They can also start the boat’s engine, but they do not produce as much power to that of what car batteries release when cranking a car’s engine.
However, the good thing about marine batteries is that they can still supply power to other electrical devices that are running while the boat is moving even for a prolonged period of time.
This means that marine batteries produce more power, which can last longer while having enough power to start a boat’s engine.
A boat’s motor requires less power to start. This is why marine batteries for a trolling motor doesn’t have any problems starting despite the fact they can’t do the same with a car’s engine.
Nevertheless, you can also use marine batteries at home or in your outdoor activities such as camping in order to power your lights and even power a sound system.

2. Plates

Both car batteries and marine batteries have differences in battery construction in which plates are immersed into sulfuric acid and an electrolyte solution. The reaction among plates, electrolytes, and acid produces an electrical discharge.
The differences in the size of the plates also affect the level of power supply they produce. Thinner plates can quickly release power but only for quick moment while thicker plates slowly release power, but they can continue producing power for a much longer time.
Such differences may provide you with a clue about the differences between car batteries and marine batteries in terms of plate size.
Car batteries have more and thinner plates while marine batteries have thicker ones.

3. Discharge Limit

It’s important to know the discharge limit of a battery, so that you are aware if your battery can no longer provide more power. Another reason is to optimize your usage.
When you always use your battery beyond its discharge limit, its battery life is more likely to shorten. In addition, overuse can cause safety issues down the road.
For car batteries, the discharge limit is 20% of its full capacity. For marine batteries, it’s 50%.

Why Would a Marine Battery Crackle?

Marine batteries are very powerful, but they are also stable because they are shock-proof. This means you can use it in a boat that is running on rough water conditions, which makes the battery itself safe and durable.
Ironically, it’s common for marine batteries to produce some crackling sound. If you are a beginner, this may be alarming. Nevertheless, the crackling sound is a sign that you are going beyond the discharge limit.
When you hear such noise, try to reduce the discharge. Furthermore, monitor the temperature of the battery because overheating may also cause a crackling sound.


Apparently, marine batteries are more expensive than car batteries. This is because their plates are thicker, and thicker plates produce more power, and marine batteries are sturdier than car batteries.
The only drawback is that marine batteries have less battery life than that of car batteries. The reason for this is that car batteries don’t work that much compared with marine batteries.
We hope you’ve learned the difference between the two batteries, and all your questions have been answered.