Onboard Boat Battery Charger: A Guide on Choosing the Right One

learn to pick the right chargerBattery power is crucial to all the boaters out there. It’s an essential component for starting engines and running the boat’s entire electrical grid; providing power to lights as well as the accessories of the boat.

This only shows that managing your charging needs will play a huge role in sustaining the power needs of your boat. Fortunately, most of the modern battery chargers today has the “smart” feature that will allow you to manage your charging needs easily. But if you want the easiest way, getting the right onboard boat battery charger is the best option.

When it comes to buying an onboard charger for your marine battery, you have to make sure that the charger you will buy works perfectly with your battery.

To do this, you will have to consider several important aspects and think about a number of considerations. If you don’t have any idea about it, then I suggest that you stick with me as I go along these things.

Considerations in Buying An Onboard Marine Battery Charger

The Specifications of the Marine Battery

Prior to purchasing an onboard marine charger, you first have to consider the complete specifications of your marine battery. Thinking about the type of battery you have on board, its amp-hour rating, battery capacity and voltage will help you ensure that the charger will perfectly work with your batteries. With the knowledge of the specifications of your batteries, you can also pick the right charger that will provide a variety of charging options. Allowing you to manage your charging needs easily.

The Voltage of the Charger that You Need for Your Batteries

Depending on your boat’s battery configuration, you will also need to think about the minimum voltage the charger can deliver. This is to make sure that the onboard charger that you will buy is capable of properly charging the batteries on your boat. This will crucially depend on how your batteries on your boat are configured. To give you an idea, here are some examples.


1. If your boat has a single 12-volt marine battery, a 12-volt charger will do
2. If your boat has two 12-volt batteries and they are in a parallel setup, you need a 12-volt charger
3. If you have two 12-volt batteries and the setup is in a series connection, you need a 24-volt charger

Keep in mind that using a 24-volt battery charger on a 12-volt battery is very dangerous to both the battery and the charger. It can also cause fire or explosion which is a really bad scenario. So, make sure to consider your boat’s battery configuration to be sure that everything will work perfectly.

The Amperage of the Marine Battery

Getting to know the amperage of boat batteryYou also have to think about the amp-hour rating of your marine battery before buying an onboard charger. It indicates the output of the battery that will help determine the amperage from the charger that you need. For you to know how much electricity or ampere from the charger needs to recharge your battery. Just take 10% of the battery’s amp-hour rating from its original value.

In case your boat has multiple batteries on board, you simply have to add up all the amp-hour ratings of the batteries. Then take the total and multiply it by 0.10 (10%), the result will be estimated amperes you will need to recharge them.


Let’s say your boat has 4 batteries with an amp-hour output rating of 105 AH each. To get how many amps the charger needs to provide to recharge them all, you will need to add the AH rating of each of the battery and get the total output.

Battery 1 + Battery 2 + Battery 3 + Battery 4 = Total Amp-Hours
105 AH + 105 AH + 105 AH + 105 AH = 420 amp-hours

Then take the total amp-hour output rating of all the four batteries then multiply it by 10% which will be equal to 0.10. Since you will need at least 10% of the total output of the batteries for you to recharge them.

The amount of electricity you need for the charger to recharge the entire system will be at least 10% of the total amount of output of the system, which will be 10% of 420 amp-hours.

Total Amp-Hours x 0.10 = Amperes needed to recharge the batteries
420 amp-hours x .10 = 42 amps

In this case, the right charger that will suit your boat system charging configuration. Is the device that can deliver at least 42 amps.

Environmental or Weather Conditions

Since we are talking about marine batteries and onboard chargers, environmental conditions can also be the cause of a charger’s premature failure. In buying an onboard boat charger, you have to make sure that the device you will get can endure higher humidity and moisture levels.

Most of the later versions of chargers today are engineered to be moisture resistant, and they are usually mounted within the engine compartment or another location. To minimize the charger’s exposure to moisture and water. However, looking for a fully waterproof marine battery charger is the best option.

Smart Charging Features and More

Finally, to be sure that the charger that you will get will make it easier for you to manage your charging needs. You have to consider the features the charger has to offer. Going for the chargers with the Smart Charging features will eliminate the risk of damaging your batteries due to overcharging and other charging issues. It will also allow you to manage your boat’s entire charging needs efficiently.

What’s next

An onboard boat battery charger can be an expensive investment, but the benefits of having one are far too great if you’re going to take a look at it closely. However, if you plan to get one for your boat, you have to make sure that you are getting the right one. By thinking about the significant aspect listed above, you will be able to come up with a smart decision and lead you to the best charger for your needs.

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