Onboard Marine Chargers: Best 3 Bank Battery Charger

3 bank battery chargers are commonly used for charging several (up to 3) batteries at once, using just one battery charger.

Most onboard battery chargers are designed to be permanently connected to the batteries, which are then charged whenever the battery charger is plugged in the mains power.

3 bank battery chargers are commonly used on boats, yachts, electric vehicles, RVs, off-the-grid, and other applications that have the need to charge multiple batteries at once.

Updated: January 28, 2023.

On This Page: 3 Bank Battery Chargers Features and Specifications 3 Bank Battery Chargers Comparison Chart Best 3 Bank Battery Charger Models NOCO Genius GENPRO10x3 Battery Charger Minn Kota MK 330PCL Precision Battery Charger ProMariner ProSport HD20Plus Battery Charger Guest ChargePro 10/10/10 Battery Charger Frequently Asked Questions Few Final Words

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3 Bank Battery Chargers Features and Specifications

When looking for "the best" 3-bank battery charger, be sure to check its features and specifications, including:

Charging Current

3 bank battery chargers are able to charge 3 batteries at once. Thus, each battery charger features a current per bank value and a total current (all banks combined).

Most battery chargers can provide the same charging current per single bank (for example, 5 Amps per 3 banks equals a total of 15 Amps), but there are battery chargers that feature variable charging currents with a total charging current being limited to the maximum value (for example, bank1=3A, bank2=7A, bank3=10A for a total of 20 Amps) that the unit can provide.

Charging currents of deep cycle batteries depend on their capacity, with 5-6 Amps being enough for up to 50-60 Ah batteries and 10-15 Amps (these chargers are often labeled "professional") being enough for up to 100-120 Ah batteries.

Really large batteries, for example, 4D, 6D, and 8D batteries, must be charged using so-called "industrial" battery chargers.

Supported Battery Types

Most 3-bank battery chargers support the charging of various lead-acid batteries, including wet/flooded, calcium, Gel-cell, and AGM batteries.

Battery chargers intended only for lead-acid batteries, but without advanced charging modes like desulphation and equalization can be used to recharge 12V Lithium Iron Phosphate (LiFePO₄) deep cycle batteries, but due to the voltage differences, LiFePO₄ batteries will not be fully recharged.

If 12V lithium batteries with Battery Management Systems (BMS) are being recharged using battery chargers intended only for lead-acid batteries and these chargers feature advanced charging modes (desulphation, for example), such battery chargers may damage the BMS and thus destroy the lithium batteries.

For short, always charge lithium batteries using battery chargers that feature dedicated lithium battery charging modes.

Temperature Compensation

The charging voltage of lead-acid batteries varies with temperature - these batteries require lower charging voltage during summer and higher charging voltage during cold winter days.

In order to avoid batteries being overcharged (common summer issue) or undercharged (winter issue), it is highly recommended that the battery charger have either a built-in temperature sensor or, preferably, a temperature probe.

Note: temperature sensor measures air temperature around the battery charger, while a temperature probe may measure air temperature around the batteries - a temperature probe allows the battery charger to be in different areas/rooms from the batteries.

Deep Discharge Recovery

During their use, lead-acid batteries should not be discharged below 70-80% DoD to increase their number of charging/discharging cycles.

However, when lead-acid batteries are discharged down to 100% DoD or even down or below 1V, they still can be saved with a battery charger that supports the recovery of so-discharged batteries.

Although this is not an absolute requirement, deep discharge recovery features are a highly desirable function for a battery charger that is used to charge lead-acid batteries that cycle a lot.

Waterproof Level

Marine, RV, and other battery chargers are not intended to operate under the water, however, having good water and dust protection is a very important feature.

While waterproof level varies, the recommended value is IP68 - The first digit (6) means "Protection from contact with harmful dust", while the second digit (8) means "Protected from immersion in water with a depth of more than 1 meter for longer than 30 minutes."

Cooling

Battery Chargers are not ideal, and when they operate, they dissipate heat - most battery chargers feature energy efficiency in the 85% to 90% range.

The excess heat can be removed using active cooling systems (fans, for example), or passive cooling systems (external cooling fins, for example).

A passive cooling system in the form of cooling fins requires the user to mount the battery charger in the recommended position to improve the airflow around the charger and hence the cooling effect.

Nonetheless, regardless of the battery charger, it is recommended to place them in a cool, well-ventilated area.

Safety Features

For battery chargers to operate as safely as possible, the user has to read and understand the Owner's Guide/manual that comes with every battery charger and operates the battery charger as recommended by the manufacturer.

Only then do all the built-in battery charger safety features make sense.

Most common safety features include Short-Circuit protection, Open-Circuit protection, Overheating protection, Overcharge protection, Spark-Proof, Reverse Polarity protection, etc.

Again, modern battery chargers are very efficient and safe-to-use devices, but they are NOT toys!

Warranty

3-bank battery chargers are strong, reliable, and durable devices that are built to last - most models come with 2- or 3-year limited warranties.

If the battery charger is used as recommended, there is a great chance that it will operate for many years to come. If it is abused in any way, well, it may endure some time, but one should expect it sooner or later to fail.

Other Features

Other features differ from charger to charger - for example, some battery chargers allow the user to charge different battery types on each bank, some battery chargers may feature Bluetooth monitoring (although still relatively rare), etc.

When looking for a new 3-bank battery charger, be sure to choose according to your own needs and requirements. 

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3 Bank Battery Chargers Comparison Chart

The following chart lists some of the most popular 3-bank marine battery chargers with their most important features and specifications:

Of course, there are many more models available on the market, but these are the most popular ones.

Also, if You are looking for stronger battery chargers, go for "industrial" models - they are more expensive but also more powerful.

For example, NOCO Genius GX3626 is a single-bank battery charger intended to charge 36V lead-acid and lithium batteries with a charging current of up to 26 Amps:

Again, there are other similar chargers on the market offered by other reputable brands, too.

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Best 3 Bank Battery Charger Models

Picking "the best" 3 bank battery charger can be difficult for a simple reason - personal needs, requirements, and even brand preferences may play a significant role in choosing "the best" model.

Here is our list of Top 3 Bank Battery Chargers with a short review:

• NOCO Genius GENPRO10x3 Battery Charger
• Minn Kota MK 318PCL Precision Battery Charger
• ProMariner ProSport HD20Plus Battery Charger
• Guest ChargePro 10/10/10 Battery Charger

Again, there are other brands (Schumacher, for example) that manufacture very good models, so if You can find one that fits your needs and can be found at an acceptable price, why not ... 

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NOCO Genius GENPRO10x3 Battery Charger

NOCO Genius GENPRO10x3 Battery Charger is a rather versatile 3-bank battery charger supporting charging of wet/flooded, calcium, enhanced, maintenance-free, Gel-cell, and AGM lead-acid batteries and lithium batteries.

The user can set different battery types for each bank. And when the battery is fully charged, the battery charger switches to battery maintenance mode, allowing the batteries to be connected to the charger permanently.

NOCO Genius GENPRO10x3 safety features include protection from Short-Circuit, Open-Circuit, Overheating, Overcharge, and Reverse Polarity. Also, the charger is spark-proof.

As a charger, it can be used to repair deeply discharged batteries (down to 1V) and to force-charge batteries discharged down to 0V!.

NOC Genius GENPRO10X3 features an IP68 water protection level - according to the manufacturer, it can operate for at least 30 minutes in water 1m deep.

The cooling system is passive.

The unit accepts a broad range of voltages, including line voltage from 120V to 240V AC and frequency from 50Hz to 60Hz.

Also, the operating temperature is from -4°F to 104° F (-20°C to 50°C), with the storage temperature from -22°F to 140° F (-30°C to 60°C). Also, recommended relative humidity is from 0 to 95% (non-condensing).

NOCO Genius GENPRO10X3 comes with 72 inches (182cm) 14 AWG DC cables (eyelets included) and 72 inches (182cm) 18 AWG AC cables.

Cables are built to be resistant to oil, gas, grease, water, UV light, abrasion, various chemicals, etc.

NOCO Genius GENPRO10X3 features a 3-year limited warranty.

Note: NOCO Genius GENPRO10X3 features a charging current of 10 Amps per bank, which is enough for lead-acid batteries in the 70-100+ Ah range and for lithium batteries in the 20-100+ Ah range.

If 10 Amps per bank is too much, note that NOCO also manufactures a very similar NOCO Genius GEN5X3 battery charger (3 banks, 5A each).

For more reviews and recommendations, feel free to check the NOCO Genius GENPRO10x3 Battery Charger Amazon link (the link opens in the new window). 

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Minn Kota MK 330PCL Precision Battery Charger

Minn Kota manufactures several very similar 3-bank battery chargers, differing in Amps, charging modes, and supported battery types. For example, Minn Kota 12V 10A 3-bank battery chargers include:

• Minn Kota MK 330D Digital Marine Onboard 3-Bank Battery Charger,
• Minn Kota MK 330PC Precision Marine Onboard 3-Bank Battery Charger,
• Minn Kota MK 330PCL Precision Marine Onboard 3-Bank Battery Charger (note the "L" added after "330PC").

All three models support 10 Amps per bank (30 Amps total charging current), but Minn Kota MK 330D Digital is intended for wet/flooded, Gel-cell, and AGM lead-acid batteries. And since Minn Kota MK 330D Digital doesn't feature equalization and similar advanced lead-acid battery charging modes that may damage lithium battery BMS, it can also be used to charge LiFePO4 batteries, although the battery will not be fully charged.

Minn Kota MK 330PC Precision is intended for charging various lead-acid battery types, and it also features equalization mode - Minn Kota MK 330PC Precision should NOT be used to charge lithium batteries of any kind.

Minn Kota MK 330PCL Precision is an improved Minn Kota MK 330PC Precision battery charger that can be used to charge both lead-acid and lithium batteries.

Minn Kota MK 330PCL Precision features physical dimensions of 9.88 in x 7.75 in x 3.5 inches (~25 x 19.7 x 8.9 cm), and it weighs 8.1 pounds (~3.7 kg).

Other features include Battery Type Selection, Low-Line Voltage Compensation, Battery Equalization, Automatic Temperature Compensation, Digital Control, LED Indicator Lights, Waterproof Construction, Automatic Multi-Stage Charging, etc.

Also, Minn Kota MK 330PCL Precision comes with a 3-year limited warranty.

Just like many other brands, Minn Kota also manufactures a broad range of multi-bank battery chargers with different charging currents.

At the moment of writing this article, Minn Kota MK 330PCL Precision Battery Charger was not offered on Amazon. 

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ProMariner ProSport HD20Plus Battery Charger

ProMariner ProSport HD20Plus 3-Bank Battery Charger (model 44021) is another very popular battery charger that features physical dimensions of 7.9 x 12.8 x 2.9 inches (~20 x 32.5 x 7.4 cm), weighs 7.8 pounds (3.53 kg), it comes with 6' (~183 cm) long cables and accepts 110-120V 60Hz AC power.

Note: ProMariner ProSport HD20Plus Global (model 44029) is a very similar 3-bank battery charger that accepts 100-240V AC 50-60Hz - hence the "Global" as part of its label.

ProMariner ProSport HD20Plus battery charger features an IP67 water protection level.

This battery charger is intended for charging only lead-acid batteries (wet/flooded, Gel-Cell, AGM) and is not suitable for charging of lithium batteries.

ProMariner ProSport HD20Plus comes with various features required for an onboard charger, but one of the very interesting features is so-called "Distributed-On-Demand" charging - the battery charger features a total charging current of 20 Amps, which is distributed across the banks depending on the requirements.

This allows the battery charger to charge unevenly dimensioned and charged batteries faster - however, if You intend to charge a uniform and balanced battery pack consisting of three exactly the same batteries, this feature doesn't help.

For more reviews and recommendations, feel free to check the ProMariner ProSport HD20Plus Battery Charger Amazon link (link opens in the new window). 

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Guest ChargePro 10/10/10 Battery Charger

Guest ChargePro 10/10/10 Battery Charger features 10 Amps per bank charging current (30 Amps total) and comes with a broad range of safety features, including reverse polarity, over-current, over-voltage, over-temperature, and ignition protection.

The unit's physical dimensions are 9 x 4.1 x 8.7 inches (~22.9 x 10.4 x 22.1 cm), and it weighs ~8 pounds (~3.6 kg).

The water protection level is IP67 - the unit can't operate under the water, but it is strong and durable, very resistant to splashing water.

Guest ChargePro 10/10/10 Battery Charger is intended for charging all wet/flooded and AGM lead-acid batteries - it is not suitable for lithium batteries.

Note: different lead-acid batteries can be mixed on different channels.

Although Guest ChargePro 10/10/10 Battery Charger doesn't come with as many features as, for example, NOCO Genius GENPRO10X3, Guest ChargePro 10/10/10 Battery Charger does a very good job charging the batteries that this model supports.

Also, the unit comes with a 2-year limited warranty.

For people requiring a slightly smaller battery charger, note that there is also a Guest ChargePro 5/5/5 model.

For more reviews and recommendations, feel free to check the Guest ChargePro 10/10/10 Battery Charger Amazon link (the link opens in the new window). 

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Frequently Asked Questions

Here are some of the most common Frequently Asked Questions (FAQ) about marine batteries and their chargers.

What is the best way to charge a marine battery?

The best of charging a marine battery is by using an advanced battery charger that supports the battery chemistry of the marine battery and features a temperature probe.

For example, most advanced AGM battery chargers support charging of wet/flooded, AGM and Gel-Cell lead-acid batteries (calcium, starting, deep cycle, etc.), while some of them also support charging of Lithium Iron Phosphate (LiFePO₄) batteries.

Also, such battery chargers, after recharging the batteries, switch into maintenance mode, keeping the cells balanced and the battery fully charged.

Do you need a special battery charger for a marine battery?

Advanced battery chargers analyze the charged battery and charge the battery according to its condition. So, yes, one needs a good battery charger not only for a marine battery but for other batteries as well.

Simply, battery will perform better and last longer.

Can I trickle charge a marine battery?

Yes, one can trickle charge a marine battery to keep it fully charged; however, advanced chargers that also feature maintenance mode can periodically equalize the cells and keep the battery fully charged.

Can you use a car battery charger on a marine battery?

Old-style car battery chargers can be used to recharge marine batteries, even deep-cycle ones.

But, such battery chargers don't feature special charging modes like desulfation, cell equalization, battery maintenance, and similar. So, if You must charge a marine battery with an old-style car battery charger, charge it, but don't overcharge it. Also, as soon as possible, recharge it using an advanced battery charger that will also analyze the battery prior to charging.

Do I need to disconnect both battery terminals when charging?

Generally no, there is no need to disconnect both battery terminals when charging. However, if there are sensitive electronics onboard, just to be sure, either disconnect the sensitive electronics or disconnect the battery prior to charging - if the battery charger detects battery sulfation, it will try to break the crystals using voltage spikes that can harm sensitive onboard equipment.

What is a deep-cycle battery charger?

A deep-cycle battery charger is an advanced battery charger that features an optimized charging algorithm. The charger analyzes the battery and, if required desulfates the battery.

Also, after the charging, if required, cells are balanced. After the battery is fully charged, the battery charger enters maintenance mode - it monitors the battery, and when required, it recharges the battery again.

To charge the battery to optimal voltage, a good battery charger also must have a temperature sensor/probe.

How many Amps do I need to charge a 12-volt marine battery? Is it better to charge a marine battery at 2 amps or 10 amps?

It all depends on the battery capacity, but on average good battery charger should have a maximum charging current in the 1/6 to 1/8 battery capacity.

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Few Final Words

3-bank marine battery chargers can be very useful for charging and maintaining battery packs consisting of 3 (three) 12V batteries - such 36V battery packs are becoming more and more common on boats, yachts, RVs, electric vehicles, off-the-grid systems, etc.

But, to stay safe, when your new battery charger arrives, be sure to read the manual/Owner's Guide thoroughly and to keep it close, just in case.