Best Marine Battery Charger: Top 8 and Buying Guide

Best Marine Battery Charger
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You need reliable battery power for a long voyage, the best marine battery charger will be a wise investment. We understand nothing is more depressing than a dead battery after being excited for a whole day out. The ideal charger can quickly recharge your battery, keep it in the ultimate condition, and get ready for the next trip.

In this article, we narrowed it down to 8 top-rated marine battery chargers, ranging from different styles and prices, to help you find the most suitable one. So, let’s start!

Here is a table that compares 3 best Marine Battery Charger

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Types of Marine Battery Chargers

Based on the portability, we will divide them into 2 typical types: onboard marine battery chargers and portable ones.

Onboard marine battery chargers

This type is more popular for large boats with multiple batteries. It includes one or more sets of battery chargers in a single unit and is installed permanently on your boat at a fixed location.

Most charger companies recommend you to hook it up in a convenient position. In this way, you can easily read the indicator lights and monitor each battery’s charging process.

If you usually go on a boat trip for weeks, an onboard marine battery charger comes in handy. It allows you to charge multiple batteries over time. The power source is guaranteed constant and powerful so that your boat is never out of charge.

Portable battery chargers

In contrast to an onboard marine battery charger, a portable one has a single charger in it. That means it can only work with a battery at a time. It might be inconvenient if you have multiple batteries onboard.

That is because you have to get back to the boat to disconnect the first battery and connect the second one. However, if your boat is small and does not require much power, a portable marine may be enough.


Best Marine Battery Chargers To Buy Online

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1. ProMariner 44021 ProSportHD Series Battery Charger – Best For Heavy-duty Solution

This Promariner ProSportHD 12 charger is versatile and compatible with all types of marine batteries such as AGM, wet cell, gel batteries, etc. It has a tri-surface heat sink design with an upper, lower, and rear heat sink, which shortens the charging time to 8-10 hours.

Compared to other epoxy-filled chargers on the market, the ProSportHD model weighs only 7.7 pounds. That is a bonus point for small and medium boaters.

Despite the lightweight, it still provides a heavy-duty solution for boaters thanks to 20 amp capacity and 36-volt output for 3 different banks.

It particularly features the advanced distributed-on-demand charging technology that fully optimizes power to meet each battery’s demand onboard.

Like other smart chargers, it can also check the dual-mode battery’s status, analyze the real-time system, and run on the energy saver mode. All of these are displayed on the dashboard with simple red and green LED lights.

That is not to mention all the built-in safety features, including dual inline fuses, over-temperature, over-voltage, overload, reverse polarity, ignition, and short circuit protection. It is extremely suitable to bring on board with no worries when coming with vibration-resistant, waterproof, shockproof features.

Its performance is so great that, by far, almost all buyers feel satisfied with it. They have no negative complaints at all.


  • Tri-surface heat sink for fast charging time
  • Suitable for 3 banks
  • Simple and colorful LED display
  • Excellent integrated safety features


  • N/A

2. Guest 2720A ChargePro On-Board Battery Charger – 20A/12V – Best For Lightweight

An option for the best marine battery charger 2021 you should not ignore is the Guest 2720A. In terms of exterior design, this product has a flange-less body covered by extruded aluminum. The manufacturer uses heavy-duty end caps and sealed gaskets to make it completely waterproof. It is also shock-resistant, which can be used in both fresh and saltwater.

Weight is one of its advantages, despite being made with different materials. Only weighing 6.6 pounds, this 2-bank charger is up to 40% lighter than previous models and lighter than most plastic body chargers.

There are basic status lights to notify users about the battery and charging status. It also comes with a display and a battery fault detection light for each bank.

Designed with thick and 6-feet long cables for hook-ups, it is durable to prevent any cable breakage and strain. Another prominent feature is the fundamental safety functions that will protect it from overcurrent, over-temperature, over-voltage, reverse polarity, and ignition.

However, you might find the instructions a bit confusing, like many customers. While some marketing channels state that it can be installed either horizontal or vertical, the instruction writes only a vertical install is allowed. Besides, this charger only works with wet cells and AGM batteries, so it is impossible to charge other batteries.


  • Lightweight
  • Water and shock-resistant
  • Easy to install and use
  • Intuitive LED display of each bank


  • Confusing instructions
  • Compatible with wet cell and AGM batteries only

3. NOCO Genius G4 – Best At Number Of Banks

If you search for the best marine battery charger maintainer with numerous banks, the Genius Gen4 from NOCO is an ideal candidate. Although it is a marine-rated charger, it can also charge your vehicles and other applications.

It is compatible with all types of lead-acid (6V or 12V), gel, wet cell, and AGM batteries. These kinds are commonly found in automotive, marine, and deep cycle batteries. There is even an optimized mode for charging and maintaining 12V lithium-ion batteries.

The biggest strength of Genius G4 is 4 independent banks that can operate separately with the different charging modes.

It can detect damaged batteries, require desulfated ones, charge in cold conditions, and minimize energy consumption. The internal battery chemistry’s stabilization can improve your battery’s performance and longevity.

In particular, this 4-bank charger has advanced charging technology, which can automatically monitor, charge, and maintain your battery. What you have to do is to plug in and let the internal microprocessor do the job. You do not need to fear overcharge issues anymore.

The spark-proof technology makes Genius G4 become one of the safest as well as the best 4-bank marine battery chargers on the market. That’s because it can protect users from potential risks like reverse polarity, overheating, and overcharging.

Nevertheless, this 4.4-amp charger might not be as fast as other similar models.


  • Versatile
  • 4 banks in one
  • Fully-automatic
  • Charge, maintain, and repair batteries
  • Spark and over-charging protection
  • Energy-saving


  • A slow charger

4. Dual Electronics SS-SMS-20014 – Best Repairable Battery Charger

This made-in-USA battery charger has been the top choice of many boaters with 2 bank chargers and 15 amps. It is compatible with 12V and 24V DC voltage, with the AC input of 115VAC/60Hz. Dual Electronics especially makes this Dual Pro Professional for AGM and wet cell batteries, but it can be customized for gel batteries, too. It is the best marine battery charger for trolling motors, boats, and even other automobile batteries.

What is special about this charger? It is “green,” which means it is repairable. Whenever it gets damaged or breaks down, you can easily repair or replace it. It comes with the “DeltaVolt” smart charging technology – the advanced microprocessor.

This technology can control 5 stages when charging, automatically charge batteries, adapt to both cranking and deep cycle batteries.

It also provides multiple charging modes for different battery sizes and types. In case you want to keep your batteries fully charged in storage, there is a maintenance mode.

The charger gets the highest waterproof rating available (IP 68) and is shielded from short circuit and reverse polarity when it comes to protective features. It is completely sealed, meaning it can be drowned underwater without any damage.

Though Dual Pro is great at performance, it might be too heavy to be kept on small boats with a total weight of 14.5 pounds. Also, its power cords are short, too. Thus, you had better be careful if there is no close AC power onboard.


  • Repairable
  • Suitable for wet cell, AGM batteries, and gel (optional)
  • Works with large vehicles and automobiles
  • The DeltaVolt smart technology
  • Highest waterproof rating


  • Heavy
  • Short power cords

5. Battery Tender 022-0148-DL-WH – Bestseller Marine Battery Charger

One of the tickets for the best 12v marine battery charger belongs to the Battery Tender battery charger. It allows you to charge and maintain 4 batteries simultaneously, up to 12V at 1.25 amps each. It is the first fully automatic charger working with various machines, including marines, motorbikes, UTVs, ATVs, PWCs, and scooters. In other words, it is power sport compatible.

Battery Tender 022-0148-DL-WH occupies it with integrated cutting edge battery management. That technology optimizes the voltage level, fully charges it, and automatically changes the float mode to maintain the battery level.

There will be no more overcharging and no need for periodic checks on the charge. It is literally “connect and forget.”

It also has two red and green LED lights for you to monitor the power levels continuously. About safety, there is reverse polarity detection via microchip inside the charger. Unless it is in the correct polarity, the charger will not work.

The multiple port connectors are spark-proof to provide users with better protection and care. There are no problems or risks for both professionals and newbies when using this Battery Tender charger.

Lightweight (over 3 pounds only), compact yet sturdy and durable, this charger is a perfect option for small and medium boats. Nonetheless, it might not be suitable for urgent situations, as the charging time is quite slow.

The manufacturer only offers a 2-year warranty for this charger, and it is non-transferable, which belongs to the first buyer only. The warranty does not cover any issues and accidental damage during use. The port connectors are not weather-resistant, making them more vulnerable to rain or snow.


  • Charge up to 4 batteries at once
  • Compatible with sport vehicles
  • Automatically charges and maintain the optimum battery level
  • Spark proof connectors and automatic reverse polarity detector


  • Slow charging only
  • Vulnerable port connectors

6. Minn Kota 1831060 – Best For Powerful Performance

Many customers considered Minn Kota 1831060 as the best 2 bank onboard marine battery charger with fast charging. It is understandable as it offers 15 amps per bank.

The higher the amps are, the shorter the charging time becomes. With the precise charging system, it can control the voltage and current accurately.

Like other chargers, this one can work with all types of batteries and charge different battery types and sizes independently.

Especially for wet cell batteries, it has an equalization mode. This mode works as a desulfator, which produces a burst charge to remove all the lead plates of the built-up sulfate.

It can also sense the ambient temperature, which can affect and damage batteries when charging outside. The LED lights display the charging status, allowing you to check whether the batteries are fully charged or not.

This Minn Kota model includes a plug holder as an accessory to keep the plug all dry and safe. You can use it even for rough water days because it is water, shock, and vibration resistant.

Even though it can meet all the basic demands of boaters, there are a few overheating complaints. That means you need to take more notice while charging. Some may find it pricey, but with that great performance, it deserves it.


  • Powerful
  • Quick charging
  • Has a special equalization mode for wet cell batteries
  • Compensate for outside temperature
  • Waterproof, vibration and shock-resistant


  • Risks of overheating
  • Expensive

7. NOCO Genius Gen 2 – Best For Recovery Aging Batteries

The next promising pick from NOCO we want to introduce is Genius Gen 2. It is 100% waterproof and rated at IP68, the highest possible rating. Consequently, you can use it underwater (up to 3 meters) or in any extreme weather.

An amazing feature of Genius Gen 2 is its versatility for many batteries’ types, such as wet cell, gel, and AGM batteries from 25-230Ah. It is a 2-bank battery. But unlike other chargers, this one is compatible with 12V batteries only.

As the best onboard marine battery charger, NOCO integrates numerous safety functions in this product to protect the batteries and users from potential risks. They may include short circuits, open circuits, overheating, over-current, reverse polarity, thermal, ignition, and sparks.

In particular, the charger comes with a special mode called “abnormality protection.” If the charger is in bulk charge mode for a long time, it will automatically shut off. The batteries, then, can be damaged and die. Therefore, boaters using wet cell batteries may carefully consider it.

The technology inside Genius Gen 2 is also impressive. There is an advanced microprocessor system for intuitive smart charging technology. This one can monitor the input data to diagnose, charge, and maintain batteries. It even features a recovery mode for tired and sulfated batteries, thanks to the pulse charging features.

Genius Gen 2 involves 8 different stages in smart charging. These include analyzing, diagnosing, recovering, initializing, opportunity & bulk, absorption, optimization (float), and maintenance. They are supposed to give you the battery’s superior performance and life.

Though the manufacturer guarantees that it has overcharge protection, some overcharge issues have been reported. You had better pay attention to it while charging.


  • Charges batteries up to 230Ah
  • Waterproof IP68 Rating
  • Has recovery mode
  • Abnormality protection
  • Impressive technology
  • 8-step smart charging


  • Only works with 12V batteries
  • Comes up with overcharge issue

8. Promariner 52038 Battery Charger Protournament – Best For Advanced Technology

Another option from Promariner is Protournament. This 4-bank battery is designed to give a heavy-duty performance.

So, what differentiates it from others? It is distributed on-demand charging. Instead of using the fixed outputs, it can adapt and deliver the maximum amps to charge batteries. For example, if your first battery is almost done with charging, it will direct more amps to the other batteries to provide faster charging.

It can change and adjust to numerous battery types, regardless of lead-acid batteries, by simply switching program plugs on the backside.

In addition to a standard charger, it can normally work as a maintainer and a reconditioner to maximize the battery’s overall longevity and performance. There is a LED display showing the battery’s health and charge status.

The forced induction cooling system inside the charger is great, too. Promariner uses a special fan to prevent it from overheating and boost the charging speed simultaneously. They install many safety fuses to protect the charger from overcharge, ignition or reverse polarity. The charger itself meets the shockproof and waterproof IP67 standard, so you can feel assured when using it.

Any downsides? Compared to other 4-bank chargers on the market, this one is relatively expensive. It is a high-end product so that you will receive better performance. The 2-year warranty is also shorter than other products.


  • Distributed charging technology
  • Fast charging time
  • Compatible with all battery profiles
  • Forced induction cooling system
  • IP67 waterproof and shockproof


  • Quite pricey
  • Short warranty

Buying Guide

Buying a marine battery charger is never easy. People have questioned themselves many questions in advance to find out the best marine battery charger. To help you with that, we have simplified and put some important factors together.

1. Voltage

In theory, the battery chargers work on the same voltage as your battery. Thus, it is important to know what voltage your battery is. Most marine batteries use the 12V system, but it may not always be true. Some models can charge at either 6V or 12V. That means they can automatically switch between 2 voltages.

If you have no idea of the battery’s voltage, you need to find a charger that matches batteries of different output voltages. Many advanced modern battery chargers can diagnose and adjust currents to fit with different battery types and sizes. They can get the job done at ease.

2. Amperage rating

The amperage rating directly relates to the amount of time that a charger needs to charge a battery fully. In other words, a battery charger with a high amp rating will charge faster and shorten your waiting time.

To know what is a suitable amp for your charger, let’s do a simple calculation. Take the amp hour rating on the battery, multiple with 10%, and you will have the amp rating for your charger. For example, a 100Ah battery takes a 10-amp battery charger.

The amp rating also helps you to determine the total charging time. It equals the number that the battery’s amp hour rating divides by the charger’s amp rating. Hence, it takes 10 hours for a 10-amp charger to charge a 100Ah battery fully.

3. Battery types

There are various chemical types of marine batteries, such as flooded lead acid, gel, wet cell, AGM, and lithium-ion batteries. Each type requires a different charging method and system.

Fortunately, most marine battery chargers available are compatible with many battery types, but you still should look at yours. They have automatic microprocessors that can adapt voltage and amperage to charge many distinct types of batteries.

4. Number of banks

It is better to get a charger with multiple banks if you need to charge multiple banks simultaneously. A standard marine battery charger usually comes with 2 to 4 banks.

If you plan to charge both a deep cycle battery and a starter battery at once, a multiple-bank charger is a great purchase. It is also helpful when you have a large boat running by various batteries.

Normally, people will save money by buying a charger whose banks equal the number of batteries. Yes, it could save you money. However, it might be wiser to purchase a charger with extra battery banks if you consider adding more power in the future.

5. Size

It might seem useless, but considering the size of the battery charger is crucial, too. Especially for those who want to purchase an on-boat battery charger, the dimensions and weight matter. Space on a boat is precious, and you don’t want to struggle to carry some unnecessary excess weight. Multiple-bank chargers are usually heavy, so please keep that in mind.

A good onboard marine battery charger needs to fit the area you plan to place and use perfectly. Meanwhile, the best portable marine battery charger needs to be compact and lightweight enough for you to bring along.

6. Safety

Charging a marine battery is a dangerous task. Understanding that fear, most manufacturers equip many safety features inside their products to increase safety for both you and your battery.

A battery charger is still an electrical device, so you had better get one from a reputable brand with full safety features. They may include reverse polarity and ignition protection or inline fuses. They help to protect your battery from overheating, over-current, and over-voltage.

Vibration and shock resistance are additional features that you should look for. And especially for marine battery chargers, a waterproof rating is a must.

7. Power source

A marine battery charger needs to be recharged, too, either with continuous or intermittent AC power.

Most on-boat battery chargers connect to short power when boats are docked up. It won’t be a problem if you usually use your boat and send it back home for a day. In this case, you can buy any marine battery chargers with small amp ratings that have continuous 120 VAC power.

Otherwise, portable battery chargers are also another great option. They can refill the juice in your home without any difficulty.

8. Installation

This factor is essential for onboard battery chargers than portable ones. A small, compact charger with fewer banks is easier to be installed on a boat.

Some companies may include mounting hardware as an accessory for boaters, while some may not. In that case, you need to find a corrosion-resistant device to hook the charger up. Importantly, that device must be approved for boat use.

Simultaneously, it is necessary to follow the manufacturer’s installation instructions. That will ensure a firm and proper installation and lower any risk of damage to your boat and charger.

9. Budget

The last and probably the most important factor to consider is budget. Boating is an expensive hobby, so you may want to cut down the budget here and there. But the charger is not that thing.

Replacing a pricey item like a marine battery is never a good intention. Instead, we recommend you invest in the best marine battery charger. The most advanced technology will help you keep your batteries in decent working conditions.

Or else, you can search for a high-end charger that supports more than marine batteries. Some modern batteries are also used to charge other applications and vehicles, including cars, motorcycles, RVs, etc.

Frequently Asked Questions (FAQs)

1. Should I disconnect my marine battery if the boat is not in use?

The answer may vary. If your boat is on land, you definitely should disconnect your marine battery. In contrast, you shouldn’t do that when your boat is docked up in the water.

The reasons for that are simple. The marine battery is still drained from things like radio, clock, bilge pump, or fish finder, even when you turn off the motor.

In this case, you might not want to disconnect the battery as unexpected circumstances may happen. Instead, you should look for a charger that can become a maintainer to keep your battery full all the time.

However, if your boat is not in use for a longer time, you can disconnect the battery when it is full. That allows it to be stored safely for weeks without completely draining.

2. How to charge a deep cycle marine battery?

You can charge a deep cycle marine battery in two main ways. Firstly, you can charge the battery when it is fixed on the boat. Secondly, you can take the battery out and use a portable charger to juice it up.

People mostly use a deep cycle battery outdoors. Thus, you should charge it both outdoors and indoors.

3. Should I leave my marine battery undercharged?

Like overcharge, regular undercharge can equally damage your battery. It worsens its performance and reduces its longevity because of sulfation.

That is a phenomenon when lead sulfate crystals occur on the negative plates. They will render the charge, causing the battery undercharged. Eventually, the battery can become damaged and unusable.

4. Which one is better for marine batteries? Slow charge or fast charge?

It would be better to slow charge your batteries, no matter what battery type. The charging time directly depends on the capacity (amperage rating) of the battery. In general, people consider 10 amps or less as a slow charge, while 20 amps or more is a fast charge.

Many find a fast charge more convenient, as it saves your time, especially when you are in a rush. However, repeated fast charges may overcharge your battery and reduce its performance.

5. What is the difference between a cranking battery and a deep cycle marine battery?

A cranking battery, or a starter battery, starts the marine motor by sending power from the battery when activated. It needs to provide enough powerful bursts of energy in seconds to start the engine successfully. The battery usually has thin plates to increase more plate surface area in the battery. That allows the marine boat to start as smoothly as possible.

Meanwhile, a deep cycle marine battery offers stable and continuous power for strolling in the water. It has thicker plates, which are designed to deliver continuous power over time. It is less likely to overheat as its thick plates can withstand heavy currents and high temperatures.

Another difference between them is the charging ability. A deep cycle marine battery can be drained and charged many times, while a cranking battery cannot.

6. How long will my marine battery last?

We calculate that number based on the amperage rating of both the battery and devices. Divide the battery’s capacity by the amp of the application, and you will get the answer. However, remember that is an estimated number only, not an exact one.

A 100Ah marine battery can provide 1 amp in 100 hours, 2 amps in 50 hours, 3 amps in roughly 33 hours, etc. Take a 12-amp device as an instance. If you use it for 5 minutes per day, your 100Ah marine battery will last up to 120 days.

7. Can I use a car battery charger for marine batteries?

Theoretically, you can. A car battery charger still works on a marine battery as long as you use the correct settings. Most battery chargers are “smart,” which means they can automatically detect the battery types, adjust the proper currents and voltage to meet their demands.

There are three typical car chargers: chargers, maintainers, and reconditioners. Some might be used to revive a dead battery, not charge or maintain it. Hence, it is important to know the types of your marine battery and car charger. Don’t risk it if you are not sure.

8. Who makes the best marine battery charger?

Why don’t you check out the products from these brands: ProMariner, Guest, Dual Electronics, Battery Tender, NOCO, and Minn Kota. With the experience of years, their products will never let you down.

Final Words

Well, each product has some standout features. But overall, Promariner 44021 receives more positive reviews from customers worldwide than other competitors. Its performance exceeds our expectations.

Hopefully, after our dedicated reviews about the best marine battery charger, you choose the most suitable option that meets your demand.

4.7/5 - (23 votes)

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