Marine Batteries buying guide

Being the heart and soul of the boat, marine batteries power everything. It is a crucial piece of equipment without which your boat cannot function properly.

While selecting a battery, you have to consider several metrics. You have to understand different terminologies to pick the best option for your vessel. Gathering all the correct information can become a tiresome task.

A comprehensive buying guide provides all the information under one roof. You can quickly study the critical pointers and sort out the best option for your vessel.

So, let us start with a brief introduction and then move further into this extensive guide.

What do you mean by Marine Batteries? Why do you need them?

A marine battery, essential equipment for your boat, helps to operate the motor and power up several onboard devices. It is considered as an inseparable part of the boat when it comes to boating on the water.

Using a marine battery, you can quickly start the motor so you will not have any headache of losing power at the time of boating.

There are different types of batteries available in the market, including starting, deep-cycle, and dual-purpose batteries. However, you need to choose the right one to deal with the motor's vibration and shock.

These batteries have a robust construction and more massive plates, which are specifically designed to be used on the boats. This is why a marine battery is costlier than an auto battery. But, it is more reliable and lasts longer on the boat.

Types of Marine Batteries

1. Marine Cranking Battery

You will need a considerable burst to create a fair amount of power for engine cranking. The lead plates of the battery have a wider surface so it can produce more energy faster.

This is the reason why cracking batteries are designed with thinner plates. The battery can be recharged quickly by the engine alternator when the engine runs.

You will find a rating on the label of the battery to measure the required starting power. You should check the MCA/CA rating beforehand, and it is suggested to select a more than or equal rating to the recommended value.

2. Marine Deep Cycle Battery

It may damage the battery plates, so a deep cycle battery comes with more massive and thicker plates that can handle deep cycling.

You can check the server capacity rating to know how long it can hold a specific load. With a higher RC number, your battery will be more able to power up the accessories for a longer time.

Typically, the RC rating of a deep cycle battery is twice or thrice more than a cranking battery. Also, it can withstand more discharge and recharge compared to the cranking batteries.

3. Marine Dual Purpose Battery

It will be a crucial decision to install a deep cycle and cranking batteries separately.

If you have a smaller boat and there is not enough space to accommodate two batteries, you can consider a dual-purpose battery that can perform both starting and cycling.

However, you have to remember that the dual purpose batteries can not work effectively to start an engine like a cranking battery.

Similarly, they cannot withstand frequent discharge and recharge cycles as the dedicated deep cycle battery does.

Besides these basic types, boat batteries can be categorized according to the rating conducting medium.

4. Wet Cell Battery

The traditional batteries used on the boat are the wet-cell batteries, also known as flooded cell batteries. It contains a mixture of distilled water and sulphuric acid.

If you choose a good quality wet cell battery, it can withstand 1,000 discharge/recharge cycles, so it is appropriate for extended use.

Another advantage of the wet cell battery is that you do not need to worry about the weight and overcharging.

However, wet cell batteries require high maintenance. It will be better to check the battery cells regularly.

Also, you should be careful about acid spilling when using this better. They are less resistant to high vibration.

5. AGM Batteries

You will find the glass matting is packed between the lead plates in the AGM battery. With the help of the saturated acid electrolyte, oxygen can get mixed with hydrogen, so there is not much water refilling.

These batteries have fewer chances of acid spilling because they are sealed tightly.

You can install this battery easily. Also, they are extremely resistant to shock and vibration. The self-discharging rate of the AGM battery is even lower than the others.

But, AGM batteries are a little expensive, and they can not be replaced.

6. Gel Batteries

Gel batteries last longer as they have high shock and vibration resistance capacity. Also, they can deal with lower temperature efficiently.

These batteries are adequately sealed and filled with liquid electrolytes.

There are fewer possibilities of plate sulfation, which helps to increase the lifespan of the battery.

Gel batteries come costlier, and they also require high maintenance.

Things to deem about while selecting appropriate Marine Batteries

Size and Weight

The size and weight of a marine battery matter a lot when you want to install it on your boat. So, you must check the size and weight carefully when choosing marine batteries.

If your boat does not have enough space onboard, you will need a compact size of the battery to fit properly on the boat.

Some boats have a specific battery slot, which means the battery model should fit in the right position without any issues.

Before choosing the battery's weight, you should make sure how often you need to get the battery on/off the boat.

Generally, the battery's capacity depends on its weight, so you will get a higher capacity if you choose a larger model.

Therefore, select a proper balance of weight and size of the battery to ensure it works well.

Use

It is vital to determine the purpose of why you need marine batteries before you make your purchase. According to these batteries, you will find three options, such as a starting battery, a deep cycle battery, and the last one is a dual purpose battery.

1. Starting Battery

As you can see from the name, the starting batteries are mainly used to start the boat's motor. Using a starting battery, you will generate more power in less time, which can be very useful when you are in the water.

However, it is not very ideal for powering up electronics. Also, there will be a significant chance of damages because of the constant power discharge.

2. Deep Cycle Battery

A deep cycle battery is more reliable than a starting battery. It is designed in an advanced way to hold up the power for a long time.

So, you can use it as a steady and safe power source onboard, and you can also power up your equipment without any hassles.

You cannot use these batteries as starting batteries because they cannot create a burst of power for starting the motor.

3. Dual Purpose Battery

Many boats come with a lack of space onboard, so it becomes difficult to install two batteries. In such a case, a dual-purpose battery can be an excellent option to look for.

The main advantage of choosing a dual-purpose model is that it can help you start the motor; besides, it can power up the electronic devices.

But you may find these batteries working less effectively than a dedicated deep cycle and starring battery.

Battery Capacity

It is needless to say that the battery capacity is one of the primary factors you need to check while choosing any battery. Especially when it is about marine batteries, you must pay a little more attention to maximum capacity.

Typically, a battery's capacity is measured in ampere-hours or Ah, which determines how much power you can have from the battery effectively.

For instance, you have a battery with a rating of 20Ah, which implies that it will provide an output of up to 20 amperes in one hour. It can also mean that you will get 1 ampere in 20 hours.

It is incredibly essential for the deep cycle batteries especially, when you have several electronic devices. You should bear in mind that the battery will not drain completely.

Usually, most of the batteries have a range of discharge from 40 to 50 percent. You do not need to worry about running out of power when you are on the boat.

However, a higher-capacity battery is naturally more massive. Though it is very comfortable to carry a high-capacity unit, you should consider the size and weight if you have limited space on your boat.

It is highly recommended to connect multiple units instead of buying a larger model to get more power hassle-free.

Durability and Vibration Resistance

Another crucial buying factor that you must consider when you are about to buy a marine battery is the durability. The battery's capability to absorb shocks is also related to it.

Generally, the batteries are sensitive to vibration and shocks because of the contents they have inside. It can cause different issues like less charging capacity, short-circuiting, spilling, etc.

Therefore, you should look for sealed batteries, which can quickly curb these problems and be a better option for a boat.

Moreover, the battery should be incredibly flexible so that you can mount it anywhere you want according to your convenience, and it will fit properly in the position. This is how you will get a better chance to save more space.

Also, you should check the casing to make sure it is designed with rigid plastics. It will be beneficial as it can withstand heavy bumps and difficult weather conditions.

Reliability in marine conditions

Without considering the reliability of the marine batteries, you can not make the right purchase. You will not want your battery to completely give out the power when you are on the sea.

So, you must check the reliability of the batteries you are choosing. If the deep cycle batteries fail, you will not power up the electronic devices on board.

On the other hand, if the starting battery stops working, it will be the worst because you will have no other way to start the motor.

You should always search for a battery that has a specific design to handle the marine environment efficiently.

The first and foremost thing you should check is whether the battery is sealed correctly or not. You should also make sure that the battery is resistant to heat and shocks to perform the best onboard.

Deep Cycle vs. Cranking

There are several battery-powered devices and other equipment like trolling motors, windlass, thruster, etc. that require more power to operate. So, it will be better to choose a deep cycle battery separately for this purpose.

A deep cycle model is mainly designed to be used for frequent discharging and recharging of the devices. The battery has thicker and heavier plates, which are quite different from the cranking battery.

This is why a deep cycle battery can deal with higher and longer amperage effectively.

A cracking better is constructed with thinner plates, and it provides a thrust of voltage, which is required to crank the engine. However, you should not expect high output for an extended period.

You can also start a motor using the deep cycle battery, but you will need two or three battery systems to get the job done significantly.

Battery Maintenance and Storage

You must properly maintain the marine battery to increase its longevity. Typically, SLA batteries have very little maintenance. Nevertheless, you have to take care of the battery according to the type you choose.

1. Physical maintenance

You have to wash the battery case regularly using water and baking soda. Wipe down your marine battery entirely and leave it to dry.

Then you should clean the cables. If there are any loose connections, you should tighten them properly.

For top-post batteries, make sure that the metal post connection is protected to prevent any type of corrosion. You can use grease or petroleum jelly to create a coating on the washer.

You should check the fluids of flooded batteries and refill when needed. You should never use anything else than distilled water for refilling. Do not refill the battery with sulphuric acid.

You should not overfill the battery. If you are in a warmer area, the heat will create a thermal expansion, causing spilling.

2. Sealed Maintenance Free

You should check the charge indicator of the marine battery, so get a fair idea of the battery's condition. It will help you to understand whether you need to replace or recharge the battery.

3. Storage

When it comes to storing the marine batteries, you should ensure that the battery is fully charged before storing it. Also, you should not keep it at a fluctuating temperature. Read the instructions carefully to know the exact way to store a particular model without any difficulties.

How to charge a marine battery?

You should know the correct ways to power up the marine batteries. Some people are likely to use the engine alternator to charge the battery, but it will be better to follow the multi-step method for charging.

1. Bulk Charging Stage

This stage is essential to fill up 80% capacity of an almost empty battery. The charger uses the highest voltage and amps in this stage.

During this bulk charging stage, there is less chance of overcharging because the battery is almost empty. For a regular 12-volt lead-acid battery, the voltage may reach from 14.1 to 14.4 volts. For a 24-volt unit, the voltage will be double.

The bulk charging voltage may differ for different types of batteries. If you charge in a lower voltage, it will cause sulfate accumulation on the plate and reduce the battery's efficiency.

2. Absorption Stage

After reaching 80% of the battery capacity, it starts working in the absorption stage. The absorption stage's primary purpose is to help the battery absorb the last 18% charge at the standard absorption rate.

It can prevent overheating or excessive gassing effectively. During this stage, the voltage remains constant, but the current starts to decline. The current declines when the battery reaches almost its full capacity. But one problem with this absorption stage is that it takes a lot of time to complete.

3. Float Stage

It is the ultimate stage when the battery has a 98% charge. You will find some charges that change into the float mode when the battery has 85% of capacity, but the battery will finally be 100% charged.

During this stage, the voltage decreases between 13.2 and 13.4 volts, and it will also reduce the amps. This float stage helps to maintain readiness, and it prevents cycling issues as well.

Steps to check the battery charge

You should consider battery testing as a vital part of the maintenance routine of your marine battery. If you check the marine batteries properly at a regular interval, there will be fewer battery failure chances.

You should charge the testing process with a fully charged battery. Otherwise, you may have a false reading which you never intend for.

1. Physical battery test

You should check the broken or loose terminal to avoid the possibilities of a short circuit.

It will be wise to stop using a damaged container for safety purposes.

For flooded batteries, check the water level and refill the better cell with distilled water to maintain the level.

If the fluid color becomes dark brown, it will indicate that you need to change the battery.

2. Battery charge test

There are several steps to perform battery charge steps.

First, you should measure the specific gravity with a hydrometer. A low reading means there is sulphation in the battery.

If excess sulfate is accumulated on the plate, it will damage the whole battery. Check the manual guide to measure the specific gravity of a flooded battery.

Then, you should check the voltage of the battery. You can use a Voltmeter to check the voltage properly.

Tips to avoid battery issues

You should follow these tips so that you do not have any problems with the marine batteries –

1. Keep the marine battery in a secured battery tray. The base of the tray should be screwed to the boat. Ensure a locking strap or a tough bracket that can hold the battery to the floor. It will prevent the battery from thumping.
2. You should check the terminal connections daily to make sure that they are protected from corrosion. You may find wing nuts in the battery. Replace them with nylon locking nuts, which will not become loose quickly.
3. It will be better to carry a maintenance type charger if you do not use your boat once in a while. It is the best way to keep your battery charged when you are not out.
4. Before storing the battery, you should charge it fully and disconnect the terminals. You should store the battery in a place where you can connect it with a maintenance charger.
5. You should look for a cover for the battery terminal. Even if the battery has a lid, you should consider installing the "boot," which will prevent sparks and possible explosion.

FAQs

1. What is a battery cycle count and a deep cycle count?

A battery cycle count means the total number of times the battery can charge and discharge before getting finally dead. A deep cycle count means the battery developed for a steady output for an extended time frame.

2. How to avoid overcharging issues?

Marine batteries can have overcharging issues if a cheap battery is used to operate it. Thus, it is necessary to opt for a battery that has a charging limit. This situation can also be entirely avoided by opting for a multi-stage charger that will offer good charging in no time.

3. What are the steps to test a marine battery?

A marine battery can be easily checked for load using a voltmeter. However, you need to ensure that your battery is ultimately charged when being tested. Take your prongs and check the voltage by putting them on both sides of the marine battery terminals.

4. What is the average age of a marine battery?

Usually, all marine batteries come with a warranty period of anywhere between 1 to 3 years. The marine batteries last for at least 4-5 years to guard your boat with proper electricity supply.

Final Verdict

Marine batteries power the boat and the utilities on it that makes your ride smooth and comfortable. Here in this guide, you will get all the useful information in a well-organized manner.

Go through the pointers and make an informed purchase. Power your boat with a powerful battery and enjoy your journey.