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Marine Battery Chargers The Basics

Did you know that one of the most important and complicated decisions you can make in marine electronics is choosing the correct battery charging system for your boat? Charging your marine batteries is a simple process of driving electrical currents into your battery in the reverse direction as the discharge occurred. Although recharging batteries can be a simple process, many things do factor into your decision and play a roll in choosing the proper charger.

The goal of our experts is to help you make an informed decision when you replace or add an on-board charging system to your vessel. You are adding value to your boat by having an on-board battery charger. In addition, these chargers also offer you the convenience and the ability to charge multiple batteries at the same time. You no longer will need to drag out a portable battery charger every time your batteries need charging. Maintaining your batteries will be as easy as plugging in your boat to any 110 volt outlet.

The first step in the process is to identify what type of batteries you have on board your watercraft. You will need to look for some specifics about the batteries you are wishing to incorporate into the charging system. You will need to determine the following:


Battery type

Amp-hour capacity

Typically, in the marine world, you will be dealing with 12-volt systems. The batteries capacity is usually listed on the battery as ah or amp hour. Marine batteries will be one of the following types:

Flooded/wet cell lead acid

Starved electrolyte AMG

Maintenance free

Once you know a little about the batteries you are wishing to charge, it is time to pick a charger. I know from my years of experience tournament bass fishing, picking a charger is not where you want to cut dollars. Starting and trolling system batteries are very expensive. A good quality battery charger, backed by a top manufacturer, will prolong the life of these batteries and ultimately save you money.

Chargers typically come in single, double, triple and quadruple bank systems and should have independent outputs to charge each battery separately. The battery industry recommends charging your battery at approximately 15-20 percent of its capacity. For example, a 100-amp hour battery would be best charged at 15-20 amps. For your safety, be sure the battery charger you buy is UL listed to Marine 1236 standards and FCC compliant. If you choose a charger that is too large or small for your batteries it could damage them and decrease the life by overheating, gassing and causing excessive water loss.

Depending on what type of boating you enjoy, you will need to make sure your on-board chargers waterproof housing is designed for fresh and/or salt water. It is also important that you make sure it is vibration resistant and incorporates built-in reverse polarity protection. To prevent boil over or your battery over-heating, be sure the charger you purchase has an automatic temperature compensation, this feature adjust output depending on the temperature to assure a fast full charge in any weather conditions. We suggest getting a charger that will charge in three stages typically these stages are:

Bulk or quick charge mode - gets your batteries charged quickly

Absorption stage - brings your batteries to a full charge

Maintenance or trickle charge - keeps your batteries charged and protects batteries

I personally like units that offer on-board diagnostics and LED indicator lights to let you know the state of charge or condition of your batteries.

Once you have purchased your new on-board charger make sure it is securely mounted in your boat using stainless steel fasteners. We recommend you clean your terminals, use dialectic grease and make sure all connections are tight. Following these steps will insure years of trouble free operations. We take convenience a step further on our tournament boats, we install a receptacle plug. You are then able to plug your extension cord directly into the boat without even unlocking or opening a compartment.

Before operating your charger, be sure your batteries are not run down too far. In some cases, your charger may show you have a bad connection, even though you are confident they are properly installed, if this is the case it may be necessary to apply jumper cables from another battery to the one showing connection issues, this will allow your portable charger to recognize your batteries. Our professionals have informed us that this condition occurs often during very windy days, usually when they are operating the trolling motor for extended time on a high-power setting. On these days, batteries typically are completely depleted by the end of the day. When they plug in the charger it will indicate a bad connection. Simply using a set of short jumper cables to connect the starting battery to the trolling battery for about 3-4 minutes the battery will be picked up by the charger and the bad connection light goes out. They repeat this process until all the trolling batteries are recognized by the charger.

Happy boating