Choose the Best Onboard Marine Battery Charger for Your Boat

onboard battery charger for electronics and equipment

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A boat is a complicated machine. It operates so many systems and functions that it can be hard to understand and comprehend them all. One piece of that being electronics and how they are powered.

When I was in college, we were doing research using sonar technology on the Yellowstone River here in Montana. I remember charging batteries in my garage the night before the trip so we could use the equipment and how much of a chore that was.

The first complaint I have about all of that is that the batteries were very heavy, and most fishing boats operate several so it would be a chore to charge them manually. Thankfully, we have on-board battery chargers that take the lifting out of it.

This article may send some of you back to school on these chargers but I want to cover the basics as well for the novice angler so he or she can better understand this important piece of equipment. The first thing that you should consider is what you are going to need in terms of power and then ask yourself how fast you want the batteries to charge.

Marine batteries and auto batteries can be measured in Amp Hours and this number can determine what charger you will need. Essentially, to simplify the math, a 15-amp charger (which is a faster charger) will charge a 30-amp per hour battery in a little over 2 hours.

To simplify a higher amp charger such as a 15-amp, compare it to charging a cell phone. There are standard wall plugs to charge a phone and there are what are called “lightning wall plugs”. The difference is, one handles power output faster and more efficiently.

Why is it important to consider a higher amperage charger? Because most folks have more than a few electronics happening in their boat. Trolling motors, depth gauges, fish finders, even marine radios and stereos. They all need power.

The beauty of an onboard battery charger is that you can conveniently charge many batteries at once and, depending on the output of the model you get, you can customize the speed at which they charge as well.

Most of today’s onboard chargers also come with other useful features that enhance their performance and extend the life of your battery. These include waterproof design, shock resistance, the ability to specify what kind of battery you are charging, and circuitry that protects the battery from being overcharged/undercharged. 

In This article, I am hoping to illustrate a better understanding of these devices and offer you some great examples to get you started on your decision as to which to buy. As a rule of thumb when shopping for a marine onboard battery charger, just think of them in terms of banks. For the purposes of demonstration, we will discuss 1 through 4-bank battery chargers.

How to Choose an Onboard Boat Battery Charger

To answer this, you must look at what you must charge and consider how many separate batteries you need to charge. If you have 3 different batteries, but they only need 5 amps each, then a 3 bank 15-amp charger is probably what you need.

Personally, anything I buy that goes outside with me must have a good degree of durability. For a charger, this means shock resistance, water-resistance and secure mounting. But also consider other things like covers for any open plugs it may have.

Understand dimensions very well and measure where it is going to be mounted before you buy. Get the measurements of the charger you want, try to draw it on cardboard and cut that out. Go to your boat and see if it can fit without bending.

Remember that you don’t need to use a giant charger, a modest charger will suffice and if you do not hit the water every day, it is really not crucial that your boat charge as fast. Batteries love low and slow because of the oxygen they create when charging, doing this slowly helps keep the battery healthy longer.

When it comes down to what you will pay for an onboard battery charger, I think you find that the playing field is about the same wherever you look. Having said that, I believe that the chargers in this small group I have listed offer some of the best performance and value for your money that you will find today.

There are top-end chargers that can do more but for much more money. If you are like me and you modestly fish with modest equipment, I see no need to bankrupt yourself to have the fancier chargers.

4 Best Onboard Battery Chargers From 1-Bank to 4-Bank

Alright, so we now know a little about what to look for in an onboard boat battery charger.  Let’s now take a closer look at 4 top models available today, ranging from 1 to 4 banks with varying power outputs.

In selecting a charger, you’ll want to ask yourself how many batteries will you be working with, the amp hours of your batteries and how fast you need them charged. The more power you need to be charged, the larger the charger you will need.

As we dive into the 4 onboard chargers below, I will discuss the key selling points of each as well as what I liked about the particular model – or even what I didn’t like so much. I will also highlight what I feel are the key features and added benefits of each charger as well to help you narrow down what may be important to you in your selection.


NOCO Genius GENPRO 1-Bank 10 AMP Charger

NOCO Genius GENPRO10X1, 1-Bank, 10-Amp (10-Amp Per Bank) Fully-Automatic Smart Marine Charger, 12V Onboard Battery Charger, Battery Maintainer and Battery Desulfator with Temperature Compensation

The NOCO Genius 1 bank onboard charger does quite a bit in terms of not just charging the batteries, but also maintaining them which is something I can appreciate. It charges at 10-amps which is what you might consider an average charge rate.

This single-bank onboard battery charger is rated to charge 12V batteries but has settings to charge 12V, 12V AGM, 12V Lithium, and has a 12V Repair Mode. This makes it easy to customize the charge you are getting to get the most out of a charge session.

Other features that this little charger has are good for giving your batteries a long life. It has a feature that stops charging when batteries are full which prevents overcharging and it also can help eliminate sulfate buildup.

I also love that this unit is completely sealed and waterproof, perfect for those demanding environments. NOCO covers their products in a limited capacity for 5 years which is a good span of coverage in today’s world.

Key Features

  • Anti-Sulphate mode
  • Overcharging elimination
  • Multiple Charging Modes
  • Waterproof

Added Benefits

  • 5-Year warranty
  • Compact size
  • Multiple Accessories
Buy on Amazon


ProMariner Prosport Dual-Bank 8 AMP Charger

ProMariner 43008 Battery Charger Prosport 8 Amp, Multi

The ProMariner 8-AMP Charger is a great little charger with 2 banks for good charging on a larger scale. Now this charger operates at a lower amperage, but this is not necessarily a bad thing. In fact, I think this is the best 2 bank marine battery charger in its price range.

You can buy a 15-amp charger and charge faster but that will, over a period, take a toll on your batteries as well. Low and slow is usually in the best interest of any battery. Because of this, do not be deterred by a small amperage charger.

This charger has some great features that I really like as well. The battery maintenance mode keeps your batteries healthy and never overcharged by simply kicking in when power is needed and shutting off when it is not. This also helps to save on power usage and reduces operating costs.

This charger can also indicate in a quite simple way whether your batteries are charging, conditioning, or charged. It also features a “System OK” indicator that can quickly alert you that there is a problem with the unit.

Key Features

  • Dual bank charging
  • Battery charging indicator
  • Waterproof design
  • Battery maintenance feature

Added Benefits

  • Easy to use
  • Low amperage for long battery life
  • Compact size
Buy on Amazon


Guest ChargePro 15 AMP 3-Bank Charger

Guest On-Board Battery Charger 15A / 12V; 3 Bank; 120V Input, 2713A

The ChargePro 15-AMP Charger is a great 3 bank marine battery charger that can charge many batteries at once. This is for 12, 24, and 36-volt battery systems that require 5 amps per battery. I like this battery charger for the durability that it offers. This unit is waterproof and shock-resistant which is great for rough waters.

Other features that I like about this unit include protection to prevent overheating and reverse polarity. You must consider that a battery is just a chemistry set and an onboard battery charger needs to accommodate all of that while charging it at the same time. Therefore, these are complicated devices.

This charger is slightly larger in size than the others we have discussed but as you get more and more banks involved, the size will go up. This unit weighs around 7 pounds which is average for a 3-bank charger.

This charger has a great warranty but just don’t cut or extend any wires attached to the charger itself or it will void your warranty. This is a minor issue for what I consider one of the best 3 bank marine battery chargers around today but one worth bringing up. Simply extend your connection from the other direction instead.

Key Features

  • 3 Bank system
  • Durable build
  • Resists overcharging
  • Works with 12, 24, and 36 Volt Batteries

Added Benefits

  • Shock resistantant
  • Easy to read indicators
  • 5-amp per bank
Buy on Amazon


NOCO Genius GENPRO 4-Bank 40 AMP Charger

NOCO Genius GENPRO10X4, 4-Bank, 40-Amp (10-Amp Per Bank) Fully-Automatic Smart Marine Charger, 12V Onboard Battery Charger, Battery Maintainer and Battery Desulfator with Temperature Compensation

We have progressively climbed up the scale of chargers and arrived at the NOCO Genius GenPro 4 bank 10-amp charger. This is a larger unit that can charge quite a bit of stuff. Remember that you need to be able to charge at a rate of 10 percent or more of what the battery’s capacity is.

I like this unit because of the detail that it displays about the batteries individually and the adjustments that you can make there as well. Each bank can select what kind of battery you are charging and will even display repair mode.

Standard, AGM, and Lithium are options that can be chosen for each bank and each bank also can indicate any issue the battery or charger may be having. The selectable charging feature allows you to not only charge all banks at once but individual banks as well.

Again, as with the previous NOCO, there is a good 5-year warranty attached to this product which is a good length of time considering the type of product it is. The warranty shows that they stand behind their product.

Key Features

  • Individual Charging
  • Alert Technology
  • Multiple battery type settings
  • Waterproof

Added Benefits

  • Detailed charge info
  • Excellent warranty
  • Extremely durable
Buy on Amazon


Simplified Pastimes Are Fun Pastimes

I have many hobbies that take me outside and I can tell you that none of them are fun if I must do a ridiculous amount of unnecessary work. Like the batteries in my garage the night before a research project, it sucked the fun out of it.

An onboard battery charger simplifies things by making all your equipment that needs energy charge on one plug. This means the outlet in your garage or the generator you took to the lake can charge all those essential devices at once.

The future of charging your batteries in this convenient way is also breaking into new areas such as using solar power to either keep your batteries topped off or at least make them last up to twice as long on the water.

Just remember that you do not need to supply power to your neighborhood, get what you need and if you plan to make additions to your boat, buy the appropriate charger. Always ask yourself where you see your boat in a year or two.

Another option to help you along your way to decide is word of mouth. We anglers live off word of mouth so ask a buddy or call a local boat mechanic and see what he suggests, you will be amazed at how friendly and kind most folks are.

Because this is a little more complicated than other things, just be sure to think before you buy and make sure you are getting the right charger the first time. An onboard charger can be a great addition to your boat and simplify your fishing experience.

That is all we must do to enjoy life on the water, cut out the complications and just focus on the joy of what we love doing. Warmer weather is here, time to get your ducks in a row and hit the water.

Frequently Asked Questions About Onboard Chargers

There are a few common questions that we should address first before we look at a few examples. These are good questions and will help you understand the products better when we get further along.

How does an onboard marine battery charger work?

The simple answer to this question is, it provides a way to charge the battery(s) of your watercraft without having to remove them. Most boats offer a “point of charge” location commonly in the form of AC where you can simply plug your boat in.

How many banks do I need in my onboard charger?

Let’s consider trolling motor batteries to help us answer this question. Typically, you will need one bank per trolling motor battery. You should consider that first and foremost. Most other electronics such as fish finders and radio will require slightly less.

How much power does my onboard charger need to have?

An onboard battery charger should be capable of a charging output of 10 percent or more of the battery capacity you are charging with it. Be sure to include everything that it will be charging, and I recommend you try to go a little higher than 10 percent.

Why can’t I use a regular charger for my deep cell battery?

Deep cell batteries are designed specifically for marine use and only for specific power fluctuations. Simply put, a regular charger is a hammer, and a deep cell battery is a job that does not require a hammer.

Charging anything electronic creates heat and the deep cell battery is not designed to handle the heat. My advice is to use the proper equipment for the right battery because even if you charge a deep cell battery with a standard charger, you will never get a full charge.

Is undercharging a marine battery as bad as overcharging it?

When you allow a marine battery to be undercharged for long periods of time it will start to create lead sulfate which can diminish the life and performance of your battery. Because of this, always give your batteries a charge when returning home and make sure you store them charged.

Overcharging is just as bad as it can cause the positive plates inside the battery to begin to corrode and increase the temperature of the battery while charging, affecting its lifespan. There is a way to prevent overcharging and I will explain how.

So, you have your system all set up and you know how long it takes to fully charge them. To prevent overcharging without having to go outside to unplug, consider buying a timer for your extension cord. That way it can shut off on its own without burning up your batteries and you do not have to babysit it either.

However, overcharging and undercharging is not the big concern they used to be thanks to the built-in protection circuitry found in today’s best marine battery chargers.

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