Can You Put a Car Battery in a Boat

Our editors pick the products & services we write about. When you buy through our links, we may get a commission. Learn more.

Both marine batteries and car batteries are designed specifically to fulfill their purposes.

So, when one talks about replacing one of these with the other one, certain consequences must be taken into consideration.

This article majorly covers all differentiating factors of the two batteries, which can help us decide whether replacing a car battery with a marine one is a safe and practical option or not.

What is a Marine Battery?

A marine battery – as the name itself suggests – is employed in the engines of boats.

This battery type majorly becomes distinctive from other types of batteries by the amount of current discharge it offers.

Of course this construction has been designed keeping a boat in mind. Even when the physical sturdiness of the battery is concerned, it's more than that of a car battery, so as to be able to bear all sorts of vibrations of the boat without collapsing.

Types of Marine Batteries

If we look into the details of a marine battery, it is further divided into 3 types.

For you to be able to understand all 3 types, we'll be precisely discussing them below for your ease.

What is the Difference Between Marine Battery and Car Battery?

The very basic difference between a marine battery and a car battery is the power and current output.

Initial and continuous currents

In simpler words, car batteries have numerous thin plates present in their design. This allows them to release a higher initial current to get the engine started and the motor working. This is a more significant requirement for cars than boats.

In this manner, it's easier to understand how the relatively lesser initial current released by marine batteries is made to work for boats.

So, car batteries tend to release high currents in short periods, with recharging by the alternator, followed by it. At the same time, marine batteries release smaller currents for relatively more extended periods.

The longevity of the battery

However, this isn't all. Another significant difference to take into consideration is longevity. The thicker plates of marine batteries ensure a power discharge for a more extended period than the other type.

This is a much-needed requirement as a boat needs to keep the engine running and the lights, gauges, pumps, etc.

Price to fragility

Marine batteries have relatively higher prices as compared to simpler car batteries. However, a lot of this is justified considering the sturdiness of marine batteries. They are designed to bear all sorts of vibrations of a boat.

CCA vs. MCA rating

The Cold Cranking Amps (CCA) is a power measurement for car batteries, measured at 0°F, whereas the Marine Cranking Amps (MCA) is measured at 32°F.

Can You Use a Marine Battery in a Car? What Are the Requirements?

A marine battery does not generate the required current to start a car. However, there are times when marine batteries replace car batteries of vehicles with tiny engines.

So, yes. A marine battery can replace a car battery if it meets the requirements about voltage, CCA rate, size, and terminal positions:

Is a 12V battery that is recharged by the alternator.
Meets the high CCA rate requirements of 650 CCA, or even 800 CCA for cranking the engine.
Has the right size – the most common car battery sizes are 24, 24F, 25, 34, 35, 51, 51R, 52, 58, 58R, 59, and 65. The marine battery you choose should lie near to one of these size categories.
Has suitable terminal positions, although you might have to modify the battery hold down and possibly change the terminal ends because the size of marine batteries doesn't allow them to fit in car battery trays or allow hoods to close.

However, starting a marine battery costs more than a regular car battery.

Therefore, you shouldn't employ a marine deep cycle battery unless you intend to use the deep cycle aspect for some electronic accessories, etc.

People usually think about the hybrid battery when referring to marine batteries, which provides power to crank the boat's engine and powers the lights, stereo, and other accessories, etc.

Besides, using a deep cycle battery is harmful to the alternator.

Is it safe?

In freezing weather (under -10°C), the cranking marine batteries do not usually work, as they need an even higher power.

Even in such cases, when marine batteries do work out, it's not recommended that you use them. The reason behind this is simple: marine batteries are not designed for cars, and if they are used in cars, their life span falls significantly.

It even harms the alternator/generator voltage regulator greatly.

Conclusion

While marine or deep cycle batteries do help you replace a car battery, it's not that much of a smart choice considering all the consequences that are posed as a result.

If you want to utilise a marine battery, the best way to do so is by using it to power the car's audio system, or other similar accessories.

On that note, we conclude our article and hope we addressed all your questions. If we missed something, please let us know!

See Deep Cycle Batteries for Audio System here:

VMAX XTR27-110

Kinetik HC1200-BLU

FAQs

How many CCA do I need for my car battery?

For a lot of mid-size cars, a 650 CCA, or above, ensures that the car battery would be able to stand cold weather, and would not need more power.

But to make sure that the car starts at any climate, no matter how harsh it might be, a power of 800 CCA is recommended.

Is a marine battery better than a car battery?

No, it isn't.

To say that one of these batteries is better than the other would be unfair to their purpose. Both the batteries have been very specifically designed to fulfill their own job.

For instance, a car battery releases higher initial currents to get the engine started and motor working. Later on, the battery is just recharged.

On contrary, a marine battery gives off fuller discharges in the middle of its running. In fact, it also has a higher reserve capacity to ensure a longer, smoother running of the battery.

Is it ok to use a deep cycle battery in my car?

Yes, it is.

But remember that in doing so, you are reducing the lifespan of your deep cycle battery. If you really want to put it to practical use, it's better to use it as a second battery for the audio system, or other accessories, etc.

Can a car alternator charge a deep cycle battery?

Yes, it can.

It will work OK if you have no other alternative battery choice. It will last quite a while operating a car.

However, the deep cycle battery will not be charged fully by an alternator. Alternators are not designed to recharge depleted batteries, only a charger is capable of doing so.

But know that the marine battery is also charged by connecting it in parallel with a car battery.

Read more: How To Charge A Deep Cycle Battery Properly

Can You Put a Car Battery in a Boat

Source: https://batteryglobe.com/can-you-use-a-marine-battery-in-a-car/