Marine Battery General FAQ

As the warmer weather approaches, boating enthusiasts tinker with their watercraft to get ready for another season of fishing, watersports and relaxing on the water. Avid boaters can spend hours cleaning hulls, checking drains, waxing fiberglass and meticulously caring for teak accents.

Nothing ruins a day planned on the water quicker than an inoperable battery. When you are ready to replace the battery in your boat, it is a little more complicated than picking a car battery. Here are some frequently asked questions to help you get back out on the water.

What type of battery is best for my boat?

Marine batteries are available in several types to meet the needs of specific applications. Starting batteries operate much like your car battery, providing the necessary power needed to turn over your engine. This type of battery is best for starting a motor and powering basic accessories, such as running lights and emergency “ship-to-shore” communication equipment.

Deep cycle batteries are designed to provide high charge and discharge cycles that offer long-lasting power while out on the water. A deep cycle battery is best suited for powering trolling motors, depth finders, fish locators and onboard accessories like audio, refrigerators and other electronics for added comfort.

Another option that many boaters prefer is a dual-purpose marine battery, like ODYSSEY® Extreme Marine Dual Purpose batteries. ODYSSEY® dual purpose batteries provide the cranking amperes to start your motor and deep cycle power to operate all your onboard accessories. ODYSSEY® dual purpose batteries also are supported with a better warranty, which provides up to a three-year limited full replacement that is not pro rata.

What is an MCA rating?

The marine cranking ampere (MCA) rating refers to the number of amperes a battery can support for 30 seconds at a temperature of 32°F (0°C) until the battery voltage drops to 1.20 volts per cell, or 7.20 volts for a 12V battery. Thus, a 12V battery that carries an MCA rating of 600 Cold Cranking Amperes (CCA) tells us that the battery will provide 600 amperes for 30 seconds at 32°F before the voltage falls to 7.20V.

How can I get the most life out of a marine battery?

ODYSSEY® batteries use advanced Thin Plate Pure Lead (TPPL) technology for greater surface area that delivers more power. These Absorbed Glass Mat (AGM) batteries provide reliable power and recover well from deep discharges. They also offer a longer service life of three- to 10-years, which saves you time, money and aggravation, and 70 percent longer cycle life than conventional deep cycle batteries.

How do I care for marine batteries during the winter?

If you live in the northern states, winterizing typically entails taking your boat out of the water and conducting specific maintenance and cleaning procedures to protect the boat, motor and many of the onboard accessories. In addition, you should disconnect your battery cables to ensure none of the electronics create a parasitic load that can drain a battery.

Onboard electronics, such as communications and instrumentation systems, and especially those that maintain memory, can create parasitic loads that will drain the battery if the boat’s engine remains inactive long enough. Consider a boat that has a parasitic draw of 20 milliamps and is stored for five months with the battery connected to the load. During that period, that parasitic draw will consume more than 70 Ampere Hours (Ah). Care should be taken to ensure that the battery isn’t discharged to less than 50 percent State of Charge (SOC) to prevent internal damage and enable the engine to start when needed.

How a marine battery is stored during winter will significantly affect its performance. During the off-season, the battery should be fully charged before it is placed in storage. Most batteries that are only partially charged when put into storage may experience permanent damage and may not recover their full capacity, even if they are charged prior to reinstallation. The ODYSSEY® Marine Dual Purpose battery with advanced TPPL technology, however, has excellent deep discharge recovery capabilities. It is much more forgiving of such storage abuses than conventional AGM or flooded lead acid batteries.

Should I store the battery on a trickle charger?

Connection to a trickle charger will prevent excessive discharge of the battery from parasitic loads for boats that are only used occasionally. When using a trickle charger, it is important to know if it will adequately charge your type of battery. For example, trickle chargers are not suitable for recharging an ODYSSEY® TPPL battery that has been deeply discharged. However, they are suitable for maintaining TPPL batteries at a full SOC, provided that the float voltage setting is appropriate. For TPPL batteries, the recommended float voltage is 13.6V for a 12V battery. Be sure to follow the battery manufacturer’s charging recommendations to avoid damaging the battery. Consult a battery professional if you need guidance.

Does it matter how I mount a battery?

AGM batteries offer greater flexibility than conventional lead acid batteries in how they can be mounted, due to the sealed design. The non-spillable characteristic of ODYSSEY® marine batteries enables them to be mounted on any side in any position except inverted. The sealed design also makes these batteries virtually maintenance-free as they never require watering.

Boat owners have also found that ODYSSEY® TPPL batteries are extremely resistant to shock and vibration, perform in the harshest environments and provide improved safety. ODYSSEY® batteries are U.S. Department of Transportation classified as “non-spillable.” The sealed design means you do not have to worry about acid spills or escaping gases, which damage conventional lead acid batteries and potentially your watercraft.


Selecting the correct type of battery for your boat and following proper battery maintenance guidelines can extend the life of your batteries and ensure you have the power needed to get out on the water.

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