Marine Battery “TLC” Tips for the Spring

With the arrival of spring, boating enthusiasts look forward to taking to the water, especially in climates where it is too cold for boating during winter. Watercraft that remains dormant for a few months need to be recommissioned to ensure that all systems onboard are functioning properly. Recommissioning involves inspection, preparation, cleaning and sometimes repair or replacement of onboard components, including the marine battery or batteries. For instance, some boats use two batteries or banks: one for starting the engine and another to power trolling and house loads. Other boats use one, dual purpose marine battery.

The conventional marine battery is the flooded lead acid battery. Also known as the wet-cell battery, the flooded lead acid battery has been in use for more than a century. A flooded lead acid battery contains plates made of either alloyed lead and antimony or alloyed lead and calcium. The plates are secured with separators and immersed in an electrolyte of sulfuric acid. The electrolyte requires periodic maintenance by replenishing the fluid volume with distilled water.

About 50 years ago, Absorbed Glass Mat (AGM) lead acid batteries were introduced into the marine market. In AGM batteries, spongy fiberglass mats that absorb the electrolyte are tightly compressed between the plates, which improves the battery’s shock- and vibration-resistance. Being sealed, AGM batteries require no watering, making them virtually maintenance-free and not prone to spillage and leakage. Most dual purpose marine batteries are AGM batteries.

EnerSys® offers an advancement in AGM design with its ODYSSEY® Marine Dual Purpose batteries, featuring proprietary Thin Plate Pure Lead (TPPL) technology. These premium batteries provide greater energy density than comparatively sized conventional lead acid batteries. Among its many benefits, TPPL technology features pure lead plates that are thinner than those in conventional batteries, so more fit in the same footprint for greater surface area. This enables more electro-chemical reactions with the electrolyte, and therefore, more power. Due to the deep cycling capabilities of TPPL technology, high-quality ODYSSEY® Marine Dual Purpose batteries can recover from deep discharges that occur when powering onboard devices.

To recommission a motorboat for the spring, the boater should inspect, clean, test and charge the marine battery before taking the boat out on the water. As always, be sure to follow the manufacturer’s guidelines for battery care and handling and direct any questions to your battery professional.


 Examine the marine battery’s exterior for signs of damage or extraordinary wear, the cables for fraying and corrosion, and the connections for corrosion and unsecured mounting. Corrosion can appear as a thin white powder or a blue-green growth on the terminals.

Replace damaged cables and clamps, but if terminals or the case are damaged, typically with cracks or leaks, replace the marine battery itself.


Dirt, acid, corrosion and other contaminants that accumulate on the case or terminals can cause small current leaks. When cleaning, disconnect the battery, and remember to wear protective gear, including eye wear and gloves.

Clean away deposits on the terminals with a battery terminal brush and neutralize acid accumulation with diluted ammonia or a paste of three parts baking soda and one part water. Clean away grime from the terminals and case with water. Rinse and dry the battery before reconnecting it.

Once the marine battery is reconnected, insulate the terminals with anti-corrosion spray, grease or petroleum jelly to prevent deposits from reoccurring.


When charging a marine battery, the charge current must be high enough to provide a full charge. The charge voltage must be appropriate for the battery type to avoid overcharging, which can damage the battery. Be sure to follow the manufacturer’s guidelines for proper charging.


 Testing will help determine the marine battery’s State of Health (SOH). A digital voltmeter measures a battery’s Open Circuit Voltage (OCV), which is directly related to its State of Charge (SOC). For an accurate reading of the battery’s OCV, the engine should be off for at least six hours to ensure that the surface charge is gone. The battery manufacturer’s specifications will indicate what OCV corresponds to 100 percent SOC, as well as what charge is needed. When OCV readings are lower than specifications require, especially after charging, the battery may no longer be viable. If so, consult a mechanic or battery specialist.


 The battery may not recharge if it was stored at only a Partial State of Charge (PSOC) or if it has exceeded its service life. If the battery needs replacement, follow these guidelines:

  • Disconnect all cables from the battery and remove the battery (be sure to take it to a battery recycling exchange center)
  • Set the replacement battery in the holder and secure it in place
  • Connect the positive cable to the positive terminal and the negative cable to the negative terminal
  • Tighten the bolt, screw or nut to its appropriate battery torque specifications

 The ODYSSEY® Marine Dual Purpose battery will start the engine and power trolling and house loads, as well as simplify storage, decommissioning and recommissioning between seasons. It also offers slower self-discharge and faster recharging than conventional flooded lead acid batteries. With the proper care, charging, storage and installation, the ODYSSEY® Marine Dual Purpose battery should deliver reliable service through years of use and enjoyment.

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EnerSys, the global leader in stored energy solutions for industrial applications, manufactures and distributes energy systems solutions and motive power batteries, specialty batteries, battery chargers, power equipment, battery accessories and outdoor equipment enclosure solutions to customers worldwide. Energy Systems, which combine enclosures, power conversion, power distribution and energy storage, are used in the telecommunication, broadband and utility industries, uninterruptible power supplies and numerous applications. Motive power batteries and chargers are utilized in electric forklift trucks and other industrial electric powered vehicles requiring stored energy solutions. Specialty batteries are used in aerospace and defense applications, large over-the-road trucks, premium automotive, medical and security systems applications. EnerSys also provides aftermarket and customer support services to its customers in over 100 countries through its sales and manufacturing locations around the world. With the NorthStar acquisition, EnerSys has solidified its position as the market leader for premium Thin Plate Pure Lead batteries, which are sold across all three lines of business. More information regarding EnerSys can be found at


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