Choosing the best onboard marine battery charger from all the available models requires some careful consideration.  Boat chargers can’t be selected in the same way as a regular vehicle battery charger because of the harsher environmental conditions facing marine chargers.

So how do you choose the best onboard marine battery charger for your application?  We have put together some selection criteria that should help you with your choice.

Environmental ConditionsBest Onboard Marine Battery Charger Noco Genius Gen2

The obvious environmental condition that dictates charger selection is moisture.  It’s a fact of life that an onboard marine charger will have to endure much higher humidity and moisture conditions than automotive chargers.  Most boat battery chargers are moisture resistant to some degree to prevent premature failure from wet conditions.

Onboard boat battery chargers usually are not directly exposed to water as they are permanently mounted in the engine compartment or other nearby location.  You only need a completely waterproof boat battery charger where your charger may experience direct contact with water such as in the case of smaller fishing boats.

Stormy Marina PictureBattery Specifications

One of the most important considerations in choosing the right marine battery charger is the type or chemistry of your batteries, their amp-hour rating, and their voltage.  Most marine batteries are hybrid batteries designed for the dual use of starting boat motors and “house” service.  They are not the same as starting or automotive batteries which depend on an alternator to keep their discharge rates at 5% or less.

True marine batteries are designed to tolerate discharge rates of to 50% and are usually much heavier than automotive batteries.

Battery VoltageYacht Picture 1

What voltage charger do you need?  It depends on your configuration, but here are some examples.

Single 12V battery = 12V battery charger

Two 12V batteries setup in parallel = 12V battery charger

Two 12V batteries setup in series = 24V battery charger

Don’t use a 24V battery charger to charge a 12V battery.  It will damage or destroy the battery and charger and also may have hazardous consequences such as a fire or explosion.

Smart Chargers

Manual marine battery chargers depend on you to monitor their operation to avoid overheating or overcharging your batteries.  The best boat chargers are the new smart chargers that have onboard computer processors capable of detecting the state of your batteries and adjusting their output automatically.  They can also be used as battery tenders providing a minimal charge to your batteries to keep them fully charged even during longer periods of downtime without overcharging.

Battery Banks

This article considers some of the best 2-bank marine battery chargers which are used for two-battery systems.  Your batteries can be configured in a variety of ways to handle your specific electrical needs.  Battery chargers with multiple banks greater than 2 are also commonly available, but are consequently more expensive.

Multiple bank chargers will work with a number of batteries equal to or less than the number of banks. For example, a 4-bank charger will charge a 2 battery system.  If you are considering a 2-bank charger and you think you might be adding an additional battery, it might be worthwhile to purchase a 3-bank charger for expansion purposes.

Boat Image 3Your batteries might not all be exactly the same voltage.  Make sure you match the voltage to your charger.  For example, if you have three batteries that need charging such as a 12V battery for starting and two 12V batteries in series to power a 24V electric motor, you should purchase a 3-bank multi-voltage that has provision for both 12V and 24V outputs.

Battery Amperage

How many amp marine battery charger do I need?  A simple calculation that works in most cases is to examine the amp-hour output rating of your battery and take 10% of that value as the proper amperage needed to recharge it.

If you have multiple batteries you will have to add up the amp-hours of all the batteries and multiply that figure by 10%.  So in the case of three 105 amp-hour batteries, you would need approximately 10% of 315 amp-hours or 31.5 amps.

There you have it.  Several criteria you can use to select your onboard marine battery charger.  Read on to see 8 great 2-bank chargers that definitely deserve your consideration.


Best Onboard Marine Battery Charger Powemania M208E#8 – Powermania M208E 2-Bank Turbo Waterproof Marine Battery Charger

Key Features:

  • Expoxy-potted for long-term waterproof and shock-resistant operation
  • 8-Amp, 2-Bank, 12/24V
  • Fully automatic 3-stage smart charger
  • Battery type selection among lead-acid, AGM, high-power AGM, and GEL cel batteries
  • Adaptive load capability (provide more power to weaker battery)

#7 – Marinco Guest 2620A Charge Pro 20 Amp Marine Battery ChargerBest Onboard Marine Battery Charger Marinco Guest 2620A

Key Features:

  • Three-stage switching electronic circuit with overload and reverse polarity protection
  • Self-protecting under extreme ambient conditions including moisture, vibration, and shock
  • Capable of charging 12V/24V flooded, Gel cel, and AGM batteries
  • ConnectCharge permanent mount system
  • Maintenance mode protects your batteries during storage
  • Comes with 6-foot AC power cord with ConnectCharge plug and 6-foot DC output cable with ring terminals
  • Lifetime warranty against water damage
  • Limited 2-year warranty against defects in materials and workmanship

Best Onboard Marine Battery Charger Minkota MK-220D#6 – Minn Kota MK 220D On-Board Battery Charger

Key Features:

  • 2-banks with 10 amps per bank
  • Computer controlled
  • Multi-stage charging and automatic temperature compensation
  • Fully corrosion resistant
  • 3-Year Warranty

#5 – NOCO Genius GENM2 8 Amp 2-Bank Waterproof Smart On-Board Battery Charger

Key Features:Best Onboard Marine Battery Charger Noco Genius GenM2

  • 8-amp (4 amps per bank)
  • Fully automatic and safe to connect indefinitely to wet cel, gel cel, maintenance-free, and AGM batteries
  • Safety features include sparkproof and protection against reverse polarity, short circuit, open circuit, overheat, and overcurrent
  • Interactively diagnoses, recovers and charges 20-120 amp-hour batteries
  • Smart charger automatically recovers deeply discharged and sulfated batteries using pulse charging technology
  • Can charge multiple battery chemistries
  • Chargers 2X faster than traditional battery chargers
  • 5-Year limited warranty

Best Onboard Marine Battery Charger Promariner Prosport Gen 2#4 – ProMariner 12 amp ProSport Gen 2 Battery Charger

  • 2-bank, 12 amps
  • Autosensing and charge distribution using Distributed-On-Demand Technology
  • Multi-stage charging
  • Automatic charging and conditioning with a built-in safe maintenance mode
  • Expanded LED status center displays AC power status, charge mode, and battery type
  • 3 – User selectable charge profiles for flooded (lead-acid)/STD, AGM, Gel, and high-performance (HP) AGM
  • Compact and rugged design is 100% waterproof and shockproof
  • Dual inline DC safety fuses
  • Safety features included dynamic thermal output control and protection against over-voltage, overload, over-temp, and reverse polarity
  • 2-Year warranty

 #3 – Minn Kota MK 210D On-Board Battery ChargerBest Onboard Marine Battery Charger Minkota MK-210D

Key Features of the MK 210D Minn Kota Battery Charger:

  • 2-banks with 5 amps per bank for a total of 10 amps total output
  • For use with 12 or 24 volt systems with 12V/6-cell batteries including flooded/wet cell, maintenance free and starved electrolyte (AGM) only
  • Digitally controlled microprocessor monitors temperature and charge state
  • Multi-stage charging (bulk, absorption, and maintenance) and automatic temperature compensation for better charging in extreme temperatures
  • Enhanced status codes display charge stage, maintenance mode status, errors, and full charge
  • Automatic shut-off when charge is complete
  • Durable waterproof, corrosion-resistant, shock- and vibration-resistant aluminum contruction
  • Protection against short circuit and reverse polarity
  • Ignition protection
  • Includes one 6-foot AC power cord and two 6-foot fused output cables
  • 3-Year warranty

Best Onboard Marine Battery Charger Marinco Guest 2611A#2 – Marinco Guest 2611A Charge Pro Series Marine Battery Charger

Key Features:

  • 10 amps total output (5 amps per bank)
  • Three-stage switching electronic circuit
  • Built-in protection against short circuit, ignition, and reverse polarity
  • Fully potted and self-protected against harsh conditions like moisture, vibration, and shock
  • Charges both 12V and 24V flooded, gel, and AGM batteries
  • ConnectCharge permanent mounting system
  • Maintenance mode protects batteries from overcharging during storage
  • Lifetime warranty against water damage
  • 2-Year limited warranty against defects

#1 – NOCO Genius GEN2 20 Amp 2-BankBest Onboard Marine Battery Charger Noco Genius Gen 2 Best Onboard Marine Battery Charger

Key Features:

  • 2-Bank, 20-amp, 12V total output, 10 amps per bank
  • Fully automatic charger, Smar VosFX processor-controlled, designed for 25 to 230 amp-hour applications
  • Safely charges multiple battery chemistries including wet, gel, maintenance-free, and AGM
  • Complete, advanced 8-step charging process charges and maintains marine batteries
  • Charger monitors power input, battery condition, and charger stages for longer battery life and improved battery capacity
  • Safety features include protections against reverse polarity, short circuits, open circuits, sparks, overheating, overcurrent, overcharging, and other abnormalities.
  • Rugged, sealed, waterproof housing carries an IP68 protection rating and also meets ISO 8846 marine standards and Title 33 CFR 183.410 ignition-protection requirements.
  • Noco Genius offers a 3-Year limited warranty


Best Onboard Marine Battery Charger Comparison Chart

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