Tips for Off-Season Marine Battery Maintenance

When cooler weather arrives, you’re likely to decommission your vessel for storage until the warmer weather returns. Preparation of your boat, or decommissioning, is necessary to minimize damage while in storage. Motorboats require preparing the engine and its components, including the battery, for storage or any extended period of non-use. The following are recommendations for the proper storage of batteries. As always, be sure to follow the manufacturer’s guidelines for proper battery maintenance and care and direct any questions to your battery professional.

Preparation for Battery Storage

It’s best to store the battery separately, so remove it from the vessel and place it in a cool, dry location. Make sure it will not be exposed to temperatures below freezing, which can damage it. If you are using a conventional lead acid battery, store it safely in a plastic bin or on a surface that will not react with acid should the battery leak or become damaged. If you will be maintenance charging or trickle charging the battery (which is designed to keep the battery at a full state of charge), make sure you have easy access to it.

Perform end-of-season maintenance by inspecting cables, connections and the battery case. Remove any dirt or corrosion on the battery terminals, but if they or the case are damaged, replace the battery. If you’re using a conventional lead acid battery, check the electrolyte in each cell and, if necessary, fill to the battery manufacturer’s specified level to avoid overwatering or underwatering.

Fully charge the battery before storage to minimize sulfation, which is the accumulation of lead sulfate crystals to a level that affects with the proper functioning of the battery. A full charge will also help prevent excessive discharge from parasitic loads that onboard electronics, such as communications and instrumentation systems (especially those that maintain memory), can cause should the battery be kept in the boat. Excessive discharge will cause the voltage to decline, which will reduce the level of sulfuric acid and thereby increase the level of water, making it more vulnerable to freezing.  

Different battery chemistries require different charging profiles. Be sure to consult the manufacturer’s recommendations or contact your local battery specialist before charging it. If you are unsure of the battery being fully charged, you can use a digital voltmeter to measure its voltage, which indicates its State of Charge (SOC). The battery manufacturer’s specifications will indicate what readings will correspond to 100 percent SOC. 

Disconnect the battery cables before storage to reduce parasitic loads on the battery from any electronics that remain connected. If the battery remains inactive long enough, parasitic loads will drain it. Make sure that the battery isn’t discharged to less than 50 percent SOC to prevent internal damage and ensure the engine can start when needed.

Use a maintenance charger as an alternative to disconnecting the cables. Maintenance chargers are typically trickle chargers. Smart chargers, which prevent overcharging the battery, are also available. Chargers aren’t universal, so be sure to use the right charger and the right settings for your battery and type. Again, be sure to fully charge the battery before using trickle/maintenance type chargers.


ODYSSEY® Marine Dual Purpose Batteries

A premium Absorbed Glass Mat (AGM) battery, like the ODYSSEY® Marine Dual Purpose battery, will simplify decommissioning and storage. Unlike conventional flooded lead acid batteries that have plates immersed in a sulfuric acid electrolyte, AGM batteries contain fiberglass separators between each plate to absorb the electrolyte. AGM batteries are sealed, which makes them leakproof. No additional water or electrolyte is ever required to provide virtually maintenance-free operation.

Additionally, AGM batteries that feature advanced Thin Plate Pure Lead (TPPL) technology offer even more advantages. AGM TPPL batteries, like ODYSSEY® Marine Dual Purpose batteries, feature a military-inspired design and pure lead plates that do not corrode as the lead alloy plates in flooded lead acid and other AGM batteries can do. The TPPL plates can be made thinner than lead alloy plates so more fit into the same battery footprint, which creates greater surface area. With greater surface area, there are more electrochemical reactions with the electrolyte, which provides higher cranking capability. ODYSSEY® Marine Dual Purpose batteries also have a low self-discharge rate, which is good for storage, as well as low internal resistance, which allows them to start even in low temperatures.  

ODYSSEY® Marine Dual Purpose batteries also offer faster recharging. If it is stored without a full charge, its deep-discharge recovery capabilities make it much more forgiving of storage abuses than conventional AGM or flooded lead acid batteries. It can be brought back from 20 percent SOC to better than 90 percent SOC in about an hour, provided a high-powered charger is used.  

Proper preparation of the battery for storage during the winter will help ensure its operation when the boat is recommissioned in the spring. Choosing the best battery technology, suited for the application, storage needs and environment, makes decommissioning easier and ODYSSEY® Marine Dual Purpose batteries from EnerSys® fit the bill.

To follow the latest ODYSSEY® battery news, visit our website at or connect with us on InstagramTwitter, and Facebook by using the hashtag #MYODYSSEY.



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



Sustainability at EnerSys is about more than just the benefits and impacts of our products. Our commitment to sustainability encompasses many important environmental, social and governance issues. Sustainability is a fundamental part of how we manage our own operations. Minimizing our environmental footprint is a priority. Sustainability is our commitment to our employees, our customers and the communities we serve. Our products facilitate positive environmental, social and economic impacts around the world. To learn more visit: .