How To Choose The Right Marine Battery?

Whether you are fishing on the sea or sailing on the sea, choosing the right marine battery can make the electricity on the boat work well on the road. How do you choose a new battery when the one in your boat is no longer working? The types of batteries available at marine stores generally fall into two categories: deep-cycle batteries and starter batteries.

Types and Differences in Marine Batteries

Starter battery

Starter batteries are the type of batteries that come with automobiles and are usually made of lead acid. Starter batteries are not suitable for powering equipment. Primarily used to start an engine, a starter battery needs to provide a large amount of power in a split second.

Once the engine is running to drive the motor, the AC power generated can meet the power needs of the car or boat, such as power for air conditioning, lights, radio, etc. And the motor can also float charge the starter battery while running to keep the battery fully charged.

Starter batteries have more but thinner plates and can quickly generate high voltage and a large amount of current to start an engine, but cannot maintain a high power output for long periods. Starter batteries have a very short life and if used for long periods for equipment loads, severe depletion can result in internal damage, and it is common to have separate batteries on board for starting engines and equipment power.

Deep cycle Marine battery

There are several types of deep cycle marine batteries, including lead acid, AGM, and lithium boat batteries that can be deeply discharged without damaging the battery.

The power needs of a boat are very different from those of a car. When a boat is moored or taxiing for an extended period, the boat consumes power until it is docked and plugged in and the engine is running, and living on the boat uses electricity constantly for appliances, such as TVs, stereos, lights, probes, fish locators, and so on. Deep cycle batteries can meet the demand for long and slow discharges on the boat.

Deep cycle batteries have thicker plates that can withstand the high amperage discharges that come with prolonged use of trolling motors and anchors on a boat, whereas starter batteries have thinner plates that can twist from the heat in such situations.

Dual-Purpose Marine Battery

Having a hybrid of both starting and deep cycle battery performance provides a high burst of power to start an engine as well as provide power to equipment for extended periods.

However a single dual-purpose battery is not as efficient as individual batteries when performing the functions of a starting battery and a cycling battery. When space on a boat is limited and there is no room for multiple batteries, choosing a marine dual-purpose battery is a good option.

Classification of Marine Batteries by Chemical Composition

There are two main types of marine batteries with different chemistries, lead acid and lithium.

Lead-acid marine batteries

One of the most traditional batteries, the lead-acid battery consists of lead plates and dilute sulfuric acid. Different technological improvements have also seen the emergence of different types of lead-acid batteries:

  • Flooded (FLA) Lead Acid Batteries: these batteries usually require distilled water that should be added to the battery at regular intervals.
  • AGM and Gel Batteries: also known as maintenance-free batteries, they do not require the addition of water, they do not leak, and they have reduced self-discharge.

Lithium (LiFePO4) Marine Battery

Lithium iron phosphate battery is a new type of battery with many advantages: safe and non-leakage, no maintenance, fast charging, lightweight and durable, up to 3,000 cycles, and due to different chemical properties, the power consumption to less than 50% of the depth of discharge does not affect the battery life. The disadvantage is that the price is relatively high.

How to choose a boat battery?

Usually, a dead battery once or twice does not mean that the battery has been scrapped, it can also be a problem with appliance usage and charger. A load test can be used to determine that the battery is still in good condition, and load testing services are generally available from battery manufacturers and specialty stores.

  • When replacing deep cycle batteries, you need to look at the amp-hour rating, the number of batteries, total capacity. If there is a large amount of electrical equipment on the boat, especially if the boat is aground and anchored for an extended period, the engine is stopped and power is maintained, then a higher amp-hour rating battery will be required.
  • Replacing the starter battery is primarily concerned with the marine starter amplifier. It is necessary to refer to the boat battery manual or inform the marine dealer to make sure that the new battery’s amp-hour rating, capacity and marine starting current will fit your boat.
  • Replacing dual-purpose batteries requires attention to both starter parameters and battery capacity selection.
How to Choose Marine Batteries | Types, Sizes and Uses (Video from the Internet, in case of infringement, please contact to delete)

How to avoid problems with marine batteries?

Avoid low-temperature environments

In cold temperature environments, although the electrolyte has a low freezing point if the boat needs to be parked in some extremely cold areas where winterization is recommended, regularly charged to keep the marine battery charged, or plugged into a regulated charger.

The electrolyte concentration of an uncharged battery is relatively low and may freeze at low temperatures and cause the case to rupture.

Keep marine batteries charged

Car batteries usually last longer than marine batteries because the car is used frequently thus keeping the battery charged at all times. Batteries that are not used for a long period will self-discharge and then lose power, thus damaging the battery.

If the boat is not used often, the battery needs to be kept fully charged and disconnected from the terminal every time you go out. Where there is available power you need to link on a charger to maintain the battery charge and disconnect the power when there is enough charge. Any lead-acid battery should not be discharged beyond 50% of its rated capacity and repeated reductions in capacity to 50% may result in shorter battery life.

Secure the battery

Secure your marine battery with a solid battery tray to avoid collision damage to the battery in rough seas.

Frequently check battery terminal connections

Always check the terminal connections on marine batteries, keep the terminals clean and tight and free from corrosion,and lock nuts to avoid loose contact. Install a sheath on the positive terminal of the battery to avoid sparks caused by contact with external objects.

What sizes of batteries are available?

Batteries are available in a variety of different sizes, depending on the space you can choose the right size, common specifications are Group 4D battery, Group 8D battery, Group 24 battery, Group 27 battery, and Group 31 battery.


Different batteries make a difference in the sailing travel experience, depending on your needs and preferences. Understanding the different types (starter batteries, deep cycle batteries, dual purpose batteries) can be a good match for onboard use.

Lithium marine batteries are the best choice for those who use electricity on a boat, and lead-acid marine batteries still have a huge share of the market given their price advantage.

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