3 Tips to Choose The Best Marine Battery Charger For Your Boat

How inconvenient would it be if your laptop, tablet, or mobile phone battery went dead in the middle of you reading this article? Now imagine the stakes are a bit higher- while out at sea at a reasonable distance from shore, your boat batteries went dead!

I imagine that would be a stressful and uncomfortable situation, especially if you have guests onboard. While out on the water, a dead battery could be a boater’s worst nightmare.

For this reason, every boat should be equipped with a marine-grade battery charger to ensure your boat and equipment has reliable and consistent battery power to last the duration of your planned journey and then some.

Requirements For A Marine Battery Charger

Requirements For A Marine Battery Charger

Notice how I specifically mentioned marine-grade battery charger- although you could purchase a typical battery charger (provided it meets your boat’s charging requirements), I highly recommend that you utilize a marine-specific battery charger.

Marine battery chargers are built and tested to withstand boating demands and are waterproof (water-resistant at the minimum).

But being waterproof is not enough to determine whether a marine battery charger is suitable for your boat. You must understand your boat’s power requirements to select the most appropriate marine charger for your batteries.

What To Look For (A Step-by-Step Guide)

A marine battery charger must fit the power chemistry of your boat and suit your boating use. An ill-suited battery charger can be costly and dangerous, so take heed to the specifications of your boat’s electrical system.

Undercharging or overcharging are equally damaging to your battery and significantly reduce its expected service life. But if you incorrectly install the charger or calibrate it improperly, you are at risk for a boat fire and, in more extreme cases-explosion.

1. Battery Use

Battery Use

There are various battery applications aboard a boat to be aware of, including starter batteries, trolling motor batteries, and separate housing (cabin) batteries.

In any case, you need a starting (cranking) battery that you should use solely to turn your boat’s engine over. These batteries are similar to a car battery, so a boater should be careful not to deplete one by running other gadgets and instrumentation off of its power.

A deep-cycle battery “can [be] repeatedly drain[ed] to 80% or more of their capacity without causing damage,” and are better suited for trolling motor battery applications.

Boaters tend to switch over to a trolling motor when facing rough sea conditions or when they need to power along at slow speeds for extended periods. For those not interested in having separate batteries, dual-purpose batteries are a viable alternative on the marine market.

And lastly, boaters prefer using a separate housing battery for handling the electrical necessities within their cabin space. Besides a dedicated battery charger, you can recharge your housing battery via the boat’s engine, shore power when docked, or by solar energy.

Again, no matter the battery application, you must be sure to adequately pair a suitable marine charger to the individual battery’s specifications to avoid safety risks or costly battery replacement.

2. Power


At some point, you have probably come across the terms voltage and amperage in your typical everyday electronics. Voltage refers to the electric potential between two points, whereas amperage expresses the strength of the electrical current.

So again, when you begin searching for the best marine battery charger available, first consider the specifications of your boat’s power supply. The size of the appropriate battery charger is directly related to your battery’s voltage and supply voltage.

But that is not all. Boats utilize different types and multiple batteries simultaneously, so your charging requirements must meet the load-specific criteria for each kind of battery.

If your boat does use multiple batteries, use a separate charger on each battery or opt for a multi-bank battery charger like the Noco Genius Gen4 that is rated to charge four 12 volt batteries simultaneously.

3. Type


Since the 1800s, lead-acid batteries have been the industry standard for rechargeable batteries. But, when lithium batteries came to be approximately fifty years ago, various industries began to profit from the material’s higher rating capacity.

Boaters desire to equip their boats with an efficient, durable, and reliable power source to withstand rugged and repetitive demands while out on the water.

Dragonfly Energy reports that “lithium-ion marine batteries are more efficient, weigh less, and can last up to 10 times longer than lead-acid batteries.”

Do not think of battery chargers as a one-size-fits-all because using an improper charger is just as risky as utilizing an improperly configured battery charger.

Your recommended and safest choice is to select a marine battery charger of the same type as the batteries you have installed aboard your vessel.

How Long Should a Marine Battery Be Left To Charge?

Well, there is no exact answer. However, how often you take your boat out on the water and run its various systems will determine its battery service and recharging needs.

As a boat owner, you should anticipate recharging your boat’s batteries between trips if you do not take your boat out regularly.

If you are an avid boater and take your boat out weekly (or daily), your batteries should recharge by themselves adequately between trips. It is a good idea to check battery levels before each trip and remember to utilize charging facilities when docked to replenish your trolling and housing power.

Climate-permitting, solar panels are an efficient and green method of recharging your batteries while docked and even when out to sea.

What Is Trickle Charging?

What Is Trickle Charging

A trickle refers to a slowed or restricted flow, and that definition stays true when speaking on a marine battery charger’s behalf. For example, during the recharge cycle, the marine battery charger slows down its flow as the boat battery nears a full level of charge.

What is known as trickle charging is an alternative method of maintaining a completely charged battery over extended periods. And the good news is that both lead-acid and lithium batteries can utilize trickle charging for upkeep and long-term maintenance.

In either case, I recommend you first consult with the manufacturer of your boat’s batteries for their professional advice on trickle charging their various marine models.

Whether the demands of life restrict your passion for boating to specific periods of the year or harsh winters put a halt to getting out on the water for multiple months, numerous situations may limit the amount of sea time your boat gets.

In any case, make sure you follow proper storage and winterization procedures. In addition, you should take special care of your boat’s batteries during your particular boating off-season. Trickle charging is a great way to eliminate dead batteries during these hiatuses.

How To Maintain Your Marine Battery Charger

Batteries are like a heart- they are the life source that gives your boat its first breath. Batteries also maintain adequate flow to the various electrical components aboard for personal leisure or more critical instrumentation such as marine navigation systems.

Batteries are not cheap as it is, and if you happen to choose a lithium battery, then expect to pay a higher up-front cost, although these more modern alternatives should last longer than old-age lead-acid batteries.

So, to take advantage of the expected service life of both your battery’s and charger, be sure to do the following:

#1) Buy Marine-Grade

Buy Marine-Grade

First and foremost, do not try to save a few bucks by plugging in an old automotive battery you have had lying around the garage. Also, do not try to get away with a battery charger on sale at your local Autozone.

Your boat is an investment, not only financially, but one with big payoffs such as enjoyment and safety. So instead, go to your nearest marine dealership or visit a trusted online marketplace such as WestMarine and spend the few extra dollars to acquire battery’s and a charger specifically rated and tested for boating use.

#2) Ensure Proper Mounting

If you look under the hood of your car, you’ll notice that your car’s battery does not slide around. Usually, a tiny plate fastened by one or two bolts holds the battery in place inside of a dedicated box that often even has a lid.

At the minimum, the battery terminals will have a boot designed to help keep the terminals clean and keep you safe should your bare hands get near the battery.

The same is valid for boats- its batteries need to be appropriately mounted (no shifting) with marine-rated cables in a safe, well-ventilated, and preferably enclosed location.

If you lack the experience, there is no reason to feel inadequate because, in the marine world, there is a lot to learn. If you are new to boating, I recommend that you search for an accredited marine surveyor to assist and advise you in your electrical (and mechanical) pursuits.

#3) Smart-Charging


We have already discussed the importance of keeping your batteries charged adequately because both an under or over-charged battery can lead to expensive replacements and danger to you and the boat.

Your marine dealership will carry an array of portable marine chargers that fit your particular boat’s electrical load’s various types and power (voltage/amperage) requirements.

Mark Corke, a well-known and respected name in the marine world who has skippered two around-the-world yachts, recommends using a smart-technology three-stage marine charging unit such as the NewMar Phase Three Series 24V and 32V Marine Battery Chargers.

#4) Battery’s Unite

By planning on having multiple batteries onboard, you provide reliable electrical power to specific systems (starting, trolling, or housing). So it may be in your best interest to stick with the same kind.

Do your homework upfront and determine whether lead-acid or lithium batteries will fit you and your boat’s needs best. Then, once you have decided, utilize the same type of battery for each of your particular applications.

Sticking to all lead-acid or all lithium batteries helps to eliminate confusion and prevent the need for separate charging units.

#5) Isolate


Whenever you leave your boat, be sure to isolate your batteries properly. You would not be happy to return to a dead starting battery due to other loads depleting its charge.

There are several options for battery isolators available. Like a battery charger, the one suitable for your boat shall depend on how many batteries are onboard, amperage and voltage output, and the source of the battery charging system.

#6) It’s All About Connection

First, take safety precautions seriously, and always wear gloves when working around batteries. The pain and discomfort of battery acid spilling onto your bare skin or clothing are not worth it.

Also, remember to always clean around the battery terminals during routine maintenance to prevent a build-up of corrosion and sulfation (white powder). To clean off the top of the battery and around the terminals, you can use a simple baking soda solution, steel-wire brush (if necessary), and a lint-free rag.

Lastly, ensure that the cable-to-terminal connection is made correctly as elementary as it sounds. You risk damaging the system’s various electrical components by accidentally reversing the connection.

Pro-Tip: Always remove the black (negative) battery cable first and re-install it last to prevent sparks and electrical shorts.

Take care to properly charge and maintain your boat’s batteries by using a charger specific to your boat’s electric load. Remember to work smartly around batteries and hire a surveyor or trusted friend with marine expertise to ensure that your boat’s electrical system meets all safety protocols.


A boat’s electrical power is critical to meeting the demands of marine leisure and sports. Therefore, you must have a reliable and consistent power source to support your various aboard systems.

Maintaining adequate charge levels for your various batteries is the primary function of a marine-rated battery charger. When shopping around for the best marine battery charger, make sure to keep in mind each battery’s dedicated use, its power specifications and requirements, and type.

Last but not least, be sure to add battery and battery charger cleaning and inspection procedures to your boat’s routine maintenance schedule to maximize these products’ expected service life.

If you need further assistance in choosing the best marine battery charger for your boat, please do not hesitate to post your questions or concerns in the comment section below.

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