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Best Marine Battery Charger: The Definitive Guide

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The marine batteries and marine battery charger are vital to ensuring safe and fun water travel. One of the last things any sailor wants to encounter is a dead battery while in open water

That’s why it is highly recommended that boat owners have an onboard charger to help ensure reliable and long-lasting battery power.

When choosing a marine battery charger, there are a few things you need to consider in order to make a more informed buying decision.

How often should a marine battery be charged? How to choose a good boat battery charger? Follow the guide to find out everything you need to know!

Do I Need A Special Charger For A Marine Battery?

The answer is no. However, you must use the battery chemistry and battery voltage of your marine battery that matches your charger.

Additionally, chargers made specifically for boats will be waterproof. Preferably an IP67 waterproof charger.

Rule #1 Make sure your marine charger is compatible with the battery chemistry

Marine batteries come in four different chemistries: flooded, gel, AGM (absorbing glass mat) and lithium. When choosing a charger, make sure that the charger you choose is compatible with the specific chemistry of the battery. Otherwise, it may damage your battery and shorten its life cycle.

Because the charging and discharging principles and charging and discharging voltages of batteries with different chemical compositions are somewhat different, please be sure to match your different types of batteries with different chargers. If there are multiple types of batteries, please use a variety of prefabricated batteries matching charger.

If you want to know more details, you can read this article. 《Can I use a lead acid battery charger on a lithium battery?

Rule #2 Make sure your boat charger is compatible with your battery voltage

For marine batteries, 12V batteries are usually standard, but 24V batteries, 36V batteries and 48V batteries are also sometimes used. This is true for both starter batteries and deep cycle batteries. It is very important to use a charger that is compatible with the battery voltage.
There are 12V battery chargers, 24V, 36V, and 48V battery chargers currently on the market.(Click here to know more spec about difference voltage battery charger) Using the wrong charger can damage your battery and force you to replace it prematurely. Consult your owner’s manual if you are unsure of your boat’s voltage requirements.

Related article: 《Lithium Battery Charging: The Definitive Guide

Related article: 《How to charge lithium iron phosphate LiFePO4 battery?

How Long Does It Take To Charge Your Marine Battery? 

One of our most frequently asked questions is “how long does it take to charge your marine batteries?”

Our experts note charging time depends on the specific charger in your system. Lithium-ion batteries have low internal resistance, so they will take all the current delivered from the current charge cycle. For example, if you have a 50-amp charger and a single 100-amp hour battery, divide the 100 amps by 50 amps to come up with a 2-hour charging time.  

Another example is if you had five 100Ah (amp-hour) batteries for a total of 500Ah and a 100-amp charger. It would take about 5 hours of charging from empty to 100 percent while factoring in enough time to balance the charging cycle.

We don’t recommend you exceed this charge rate as it can lead to a shortened battery cycle life. In an emergency, the battery can be charged at a quicker rate if needed. But we don’t recommend you make a habit of emergency charging your battery. 

How To Choice The Right Boat Battery Charger?

Since the boat battery charger always work with the marine battery. So we usually need to pay attention to three points – Battery chemistry, Battery voltage, Battery maximum continuous charge current.

What chemistry marine battery that you are using?

As mentioned above, depending on the type of battery chemistry, different chargers are selected, which will not be repeated here.

What voltage marine battery you need?

When thinking about voltage, you need to know two things: supply voltage and battery voltage. The power supply is usually 120V or 240V. However, if you’re charging an alternator, it probably works on 12V or 24V and requires a DC-DC charger.

The battery voltage depends on the battery pack and can be 12V, 24V, 36V or 48V. The most common battery voltage is 12V.

What maximum continuous charge current of the marine battery?

Simply put, the more amperage your chargers have, the faster they will work. The fastest recommended rate is 0.5C for Li-ion batteries and 0.1C for lead-acid batteries. For example, C-rate means that a 100Ah Li-Ion battery pack should be charged at a maximum current of 50A (0.5 x 100Ah = 50A).

Likewise, a 100Ah lead-acid battery can only be charged at a maximum of 10A. Taking these parameters into account, it takes two hours to charge a lithium-ion battery, or ten hours if a lead-acid battery is completely depleted.

Rateled article《Battery C Rating Explanation And Calculation

Can You Overcharge A Boat Battery?

Yes, overcharging can damage your battery. But our charger has a built-in charging protection function. After the battery is fully charged, it will automatically power off and stop charging the battery.(Click here to get more spec about the boat charger)

Also, undercharging is not good for your battery, so you’ll want to make sure you charge it regularly.

How Do You Charge Marine Batteries Connected In Series?

Many marine applications require more than 12 volts of power. In particular, most trolling motors require a 24 or 48 volt power supply to operate. To run one of these, you’ll need to connect two or three 12-volt batteries together to provide the necessary voltage.

In order to charge batteries in series, you need a battery charger that matches the total voltage of the batteries in series. This means that if you connect three 12-volt batteries together, you will need a 36-volt charger. If you have four 12-volt batteries in series, you will need to use a 48-volt charger to charge them.

Rateled article《How to connect batteries in series vs parallel?

How Do You Charge Marine Batteries Connected In Parallel?

When connecting two or more batteries together to increase the ampere-hour capacity of the battery pack. This is called a parallel battery. Doing this allows the battery to last longer on a single charge while maintaining the same voltage.

In order to charge batteries in parallel, you only need a battery charger that matches the voltage of one of the batteries. So, if you have three 12-volt batteries in parallel, you only need one 12-volt battery charger.

What Is The Working Principle Diagram Of The Lithium Marine Battery Charger?

Just as below picture, nearly all lithium battery charger always take CC/CV method and an intelligent 3-step charging logic.


The Best Marine Battery Chargers

Here are a few marine battery charger suggestions:

ELBC-1220 12V 20A Lithium Battery Charger

12V 20A Lithium battery charger
ELBC-1220 12V 20A Lithium battery charger
  • Designed for 12V batteries

  • 20A continuous charge current

  • 3-step charge control with current detection

  • Super high-quality components

  • Alligator clip connectors with insulated sleeves

  • IP67 High protection level

  • Customized parameter can be acceptable

ELBC-2450 24V 50A Lithium Battery Charger

24V 50A liFePO4 Battery charger
ELBC-2450 24V 50A LiFePO4 Battery charger
  • Designed for 24V batteries

  • 50A continuous charge current

  • 3-step charge control with current detection

  • Super high-quality components

  • Alligator clip connectors with insulated sleeves

  • IP65 High protection level

  • Customized parameter can be acceptable

ELBC-4815 48V 15A Lithium Battery Charger

48V 15A Lithium battery charger
48V 15A Lithium battery charger
  • Designed for 48V batteries

  • 15A continuous charge current

  • 3-step charge control with current detection

  • Super high-quality components

  • Alligator clip connectors with insulated sleeves

  • IP54 High protection level

  • Customized parameter can be acceptable

If you did not find the boat battery charger that you want here, you can visit our battery charger product center. Or you can connect with ELB technical team to design a special battery charger meet your requirement.

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