Whether or not you can use a car battery in a boat is a very important issue. We know it can be a big hassle.
So you want to know if can I use a car battery in my boat?
You can use a car battery in your boat but you shouldn’t. Car batteries are designed to create a short burst of high power. But boats require power for longer periods of time. Also, boats have heavy-duty engines which require more powerful batteries. Thus using a car battery is not recommended.
There’s so much more to know about this. Don’t worry though cause we’ve described it in detail. Spare a few minutes and you’ll learn all about it. Let’s begin-
Why Should You Avoid Using Car Battery In Your Boat?
As we’ve said, you can use a car battery in the boat but you shouldn’t. Here, we’ve provided a quick table about the comparison of car and marine batteries. From it, you can guess quite clearly why using a car battery would be a bad choice.
| Properties | Car Battery | Marine/Boat Battery |
| CCA Rating | 150 CCA | Upto 1000 CCA |
| Lead Plate Thickness | .040″ or 1mm | More than 1mm |
| Damage Endurance | Less | More |
| Vibration Endurance | Less | More |
| Weather Protection | Greatly susceptible to water and cold | Susceptible to water and cold |
Now that you’ve got the factual information, let’s move forward to a detailed discussion.
Reason 1: The Cold-cranking Amps (CCA) Are Different
The first thing to consider here is CCA rating. It’s the number of amps a battery can support the vehicle for about 30 seconds. That is at a temperature of 0 degrees F until the voltage drops to unstable levels.
If the CCA rating is more, it means the battery can produce more starting amps. It will cause less wear on the starter motor.
The requirement for CCA rating is quite simple. Your battery should have at least one CCA for every cubic inch of engine displacement.
Moreover, There are some reasons that can cause your battery to lose cold-cranking amps. In that case, a car battery can never backup a boat.
Since the boat has heavier and more powerful engines, it needs more CCA. That means it will take more cranking amps in colder temperatures. Thus a boat battery has about 10 times more CCA rating than a car. And so, car batteries won’t suffice in boats.
Reason 2: Boat Batteries Need More Power for Longer Periods
In car batteries, chemical energy is converted to electrical energy. It’s supplied to the starter which cranks the engine.
An average car battery has a capacity of about 50 amp hours. This cranks the engine to start.
On the other hand, marine batteries are more powerful than car batteries. They provide the boat with a cranking amp for high-compression engines. They also power the heavy-duty components of the boat.
Here, an average boat battery has about 150 amp hour capacity. It not only cranks the boat’s heavy-duty engine but also somewhat supports the electrical components.
Reason 3: They Are Different in Battery Composition
Both car and marine batteries use lead-acid batteries. In both cases, their lead plates are submerged in diluted hydrochloric acid. But their internal composition is different to support their distinctive feats.
Car batteries have a greater number of thin lead plates. They are closely spaced porous plates that provide maximum exposure of active plate material. It is provided to the electrolyte while ensuring the least internal resistance.
Thus they create a short burst of high power.
On the other hand, marine batteries have fewer but thicker lead plates. They are a combination of flat and tubular plates which are high in density.
Thus they can provide power for longer periods of time which is necessary in the boat.
What Battery Can You Use in a Boat?
Now that we know it’s essential to use marine batteries in your boat, let’s move forward. Mainly there are four types of marine batteries. Let’s have a quick review of their distinctive features.
| Battery Type | Battery Capacity | Discharge Rate | Voltage |
| Starting Boat Battery | 75-400 amps for 5-10 seconds | 2%- 5% | Above 12.6 V |
| Deep Cycle Marine Battery | 50-200 amp hours | 2%- 5%Discharge limit: 80% | Above 12.5 V |
| Dual-Purpose Boat Battery | Approximately 135 amp hours | Approximately 100 amp- 800 amp | Approximately 12 V |
| House Battery for Boat | 3.5 times necessity | Approximately 3% | 13.2 – 13.4 V |
Now that you know the numeric facts, let’s move on to a detailed description. Also, consider the marine battery weight according to your boat capacity.
Starting Boat Battery
The first battery to discuss would be the starting battery. So, what is a starting boat battery?
It cranks the engine and sprinters your boat’s electrical system. Since its main job is to crank the engine, it isn’t meant to provide power for a long time. Rather it provides a burst of power for shorter periods, like 5-10 seconds.
Starting boat batteries usually have the capacity of providing 75-400 amps. Different models have different voltages. But mostly it’s above 12.6 volts.
Also, it has a discharge rate of about 2%-5%. Although it shouldn’t be totally or mostly discharged in every cycle. That is the job for another battery.
Deep Cycle Marine Battery
Next comes the deep cycle battery. So, what is deep cycle battery?
Mainly a deep cycle battery is built to withstand regularly being deeply discharged. These are mainly lead-acid batteries. They have much thicker plates than other batteries.
Deep cycle batteries are designed to power your boat for longer periods of time. This is unlike the starter battery which creates a short burst of power. So, can I use deep cycle battery to start my boat? The answer is thus obviously no.
It has a 2%-5% discharge rate. But it can be discharged to almost 80% of its capacity.
Dual-Purpose Boat Battery
Moving along, we get dual-purpose boat batteries. So, what are dual purpose marine batteries?
Dual-purpose batteries are a sort of mixture of starting and deep-cycle batteries. For an average boat, it can do both. That means it can crank up the motor as well as supply adequate power.
So, you don’t have to use different batteries for different purposes. It will help to ensure that your boat lasts longer in the water. Usually, they are 12V batteries. On average, a dual purpose battery has a capacity of approximately 135 amp hours.
As for it’s discharge rate, they can discharge currents of about 100- 800 amp. This ensures the proper function of an average boat.
House Battery for Boat
Finally, we have a houseboat battery bank. In houseboats, there’s a lot of electronic equipment, so a starting battery won’t suffice. And the battery used to power these is called a houseboat battery bank.
Generally, this type of battery has 13.2- 13.4 voltages. It also has a discharge rate of approximately 3%. Here, you should use a battery that has 3.5 times the capacity of your daily use.
Finally, we have suggested some good batteries for you to check out:
| Product 1 | |
| Product 2 |
Now that you know about the different battery types, let’s move on forward.
What Are the Boat-Specific Battery Requirements?
Knowing about the batteries doesn’t do any good if you don’t know what your boat needs. So, we’ve provided a quick table showing what’s the battery requirement for your boat.
| Boat Type | Required Battery Capacity | Battery Type |
| Daily Use Boat | About 135 Amp hour | Dual purpose batteries |
| Fishing Boats | Starting battery: About 200 amps for a short period Deep cycle battery: About 150 amp hour | Starting batteries, deep cycle batteries |
| House Boats | Starting battery: About 200 amps for a short period House battery bank: 350 amp hour for 100 amp hour use | Starting batteries, house battery bank |
Now let’s describe these facts in detail.
Daily Use Boats
Average daily use boats use the dual purpose batteries. In most cases, just one dual purpose battery is enough for these boats. They can crank up the motor and also provide power long enough for the boats to function.
Although leaving your lights or radio on for too long will drain these batteries. So, you have to be a little careful.
For most daily use boats a 135 amp hour dual purpose battery should be enough. Although depending on your specific boat this value might change.
Fishing Boats
Boats specially dedicated for fishing need more power than regular boats. They are equipped with trolling motors. You might think- can I use a car battery for my trolling motor? And the answer is no cause it might ruin your motor.
So they need a deep cycle trolling battery along with a starting battery.
The dedicated starting battery will ensure that your boat gets the necessary amp. That is for your motor to crank. And the deep cycle battery will ensure a safe and long trip. If you only use a starting battery or a deep cycle battery there may be hazards.
The powerful trolling motor may kill your battery. On long rides, deep cycling a dual purpose or starting battery might even damage them. This will make you stranded which you surely would like to avoid.
So, in order to ensure proper performance, you should use strong starting and deep cycle batteries. On average, it can be a 200 amp providing starting battery. And for the deep cycle battery, 150 amp-hour should do the trick.
Houseboats
Like fishing boats, houseboats also need a pair of batteries. This goes for sailboats and catamarons too. Like fishing boats, they need an individual starting battery top start. On top of that, they need a dedicated house battery bank.
Unlike regular boats, there are a lot of electronics in a houseboat. Lights, fans, inverters, and anything else needed for living can be found in houseboats. And the battery has to power all of them.
Thus, if you just use a starting battery it is sure to fail. It won’t be able to handle the extra load of the electronics. Thus keeping a powerful housebank ensures optimal performance.
Here, there is a simple calculation. If your boat consumes 100 amp-hour than your house bank battery should be atleast 350 amp-hour. That means you should equip a house bank battery 3.5 times more powerful than your boat consumes.
The Right Battery Size for Your Boat
Now, you might wonder if battery size also matters. Not only do you need the right type of battery, you also need the right sized battery. A bigger and more powerful boat wil naturally require a larger battery. It has to be more efficient to handle the extra load.
Thus we have provided chart of different battery sizes and their capacities. Marine battery sizes can be sorted using BCI groups. They are used depending on the requirements of the boats. So, what size marine battery do I need?
Check your boat and engine manual to verify the amount of power you need. Depending on the amp-hour and continuous amp requirement of your boat, there are different BCI groups. Go through the chart below to find the right sized battery for you-
| BCI Group | Voltage | Type | Amp hours | Continuous Amp | Peak Amp |
| 24 | 12V, 24V | Deep Cycle | 60, 75, 40 | 60, 75, 30 | 140, 150, 70 |
| 27 | 12V | Deep Cycle | 80 | 80 | 160 |
| 31 | 12V | Deep Cycle,Dual Purpose | 100 | 100 | 200, 800 |
| 31 | 24V | Deep Cycle | 52 | 50 | 100 |
| 8D | 12V | Deep CycleDual Purpose | 200, 300 | 100 | 200, 800 |
By strictly following this chart, your boat should provide top-notch performance.
How to Maintain Your Boat Battery?- 3 Tips
We’ve learnt so much about car batteries and boat batteries. It’s time to learn a bit about taking care of boat batteries. We’ve explained them below:
Ensure Proper Voltage
Ensuring the proper voltage for your battery is a must for your boat. For every battery, there’s a recommended disconnect voltage. Continuously dropping the voltage below that is harmful to your battery. Especially if you cross the reconnect voltage.
For example, you might have a 12.8 V battery and its reconnect voltage is 10V. Using your battery till the voltage drops down this limit is harmful to your battery.
So, to ensure this voltage, you can test your battery using a multimeter. If you’re using a multimeter, set it to measure voltage. Now just connect the two probes of the multimeter to the two terminals of the battery.
Connect the red probe to the positive and the black probe to the negative terminal. With that, your multimeter will show the voltage of your battery. Make sure that it doesn’t go below the reconnect voltage. Here, we would recommend maintaining a 12.5 V.
Charge Battery Fully
After measuring your voltage, if it’s down, fully charge it. So, how to charge your boat battery? Connect your boat battery to its charger. Be sure to connect the terminals right. That is positive to positive and negative to negative.
Your charger should show the voltage of your battery and at what percentage it’s in. Let it charge until it’s reached 100%. You can use your desirable charging setting but normally, keep it in a medium setting.
Ensure Proper Ventilation
So, do marine batteries need ventilation? The answer is yes. All marine batteries produce H2 as a byproduct. That is when the battery is charging. Since it is an explosive gas, if it gets stored to high concentrations, accidents might occur. Here a vent system is provided to ensure proper ventilation.
Do You Still want to Use Car Battery in Boat?
Well, in case you still want to use a car battery, we have a method. So, how to use car battery in boat?
This depends greatly on your boat and its required battery capacity. If your boat is larger and needs more power then you’ll need a higher-capacity battery. For instance, your boat might need a 24 V battery.
In that case, just using one of your car batteries won’t work. If you need a 24 V battery system then you’ll need two 12V car batteries. These are used for running heavy vehicles like trucks.
By connecting these 12 V batteries in series you can make a 24 V battery system. Also, you might not have 12V batteries in hand. In that case, you can also use normal car batteries.
For that, you can use four 6V batteries. Connect them using a two-by-two configuration. Start by connecting the negative terminal of one battery and the positive terminal of the next one. Repeat this process for all four batteries.
Then you can just connect a cable to the first battery’s negative terminal. Connect another cable to the last battery’s positive terminal. Now just connect them to your boat and you’re all set. This goes for the two 12 V battery systems too.
FAQs
Can I Recharge a Dead Marine Battery?
A unique power source for marine purposes includes deep-cycle batteries. They are made to be almost completely depleted of power before being recharged. That is to an entirely new state. Learning how to charge your deep cycle battery properly is essential to maintain your boat’s performance.
Can I Jumpstart a Marine Battery?
Although it’s technically possible, we don’t recommend using a car or other vehicle to jump-start purposes. Auto batteries and marine batteries are not the same. Therefore trying to jump-start one with the other could result in harm to your batteries. Even your car, or your boat. Thus, It’s preferable not to take a chance.
How Long Does a Marine Battery Last?
Boat batteries typically last around 3 to 4 years. Although under ideal circumstances they can even last up to 6 years. Maintain your batteries connected to a maintenance charger to always keep them fully charged. This will make sure that your battery lasts up to its whole lifespan.
Bottom Line!!
Now we want to hear from you.
Did we answer your queries related to can I use a car battery in my boat?
For sticking with us till the end, here’s an extra reward. For your trolling motor battery, you should select a deep cycle marine battery. That is of atleast 110 amp hour rating.
If there’s anything else in your mind, be sure to comment down below.
