How to Pick Deep Cycle Battery for Your Fishing Boat?

Finding the right battery for your boat can be a difficult task, and we usually get confused in the selection process. So, a quick understanding of marine batteries is a very necessary thing for boat owners.

fishing boat with Aolithium battery

Why do we need to buy batteries for fishing boats?

Because we have learned that there are many boat owners who use car batteries instead of marine batteries because of the price. This is a very wrong decision. Marine batteries are usually designed differently than car batteries, which has to do with the usage scenario. Marine batteries are able to withstand any vibration and impact that may occur on a boat. Therefore, we have to make a special marine battery for that.

Types of Marine Batteries

Marine batteries are divided into three basic types: starter batteries, deep cycle batteries and dual purpose batteries.

Starter batteries provide a quick and powerful jet of energy in a short period of time and are designed to start the engine and quickly recharge it via the engine alternator. Starter batteries should not be used for trolling boat motors or to power equipment.

Deep cycle batteries are designed to be discharged slowly over long periods of time and withstand hundreds of charge and discharge cycles. Deep cycle batteries are the right choice for powering electric trolling boat motors and other battery powered accessories such as audio systems, reels, depth finders, fish locators and applications. Deep cycle batteries should not be used in place of starter batteries.

Dual purpose batteries combine the performance of a starter battery and a deep cycle battery and are a good choice for smaller batteries when there is no room for two batteries. While they are capable of performing the tasks of both the starter battery and the deep cycle battery, they are not as efficient as the separate batteries.

How to choose the right deep cycle marine battery?

We need to first understand the available battery technologies and compare their advantages and disadvantages so that you can know what type of deep cycle battery you should choose for your fishing boat.


Lead-acid batteries - the most common and usually the most affordable. There are two basic options for traditional lead-acid marine batteries: liquid-rich batteries or AGMs (Absorbent Glass Mat). Liquid-rich batteries offer the advantage of lower cost compared to AGMs and have patented technology to resist acid delamination. These cells must be mounted vertically (terminals on top) to function properly. Older, unsealed cells can spill corrosive acid if the cell is tipped over. AGMs do not contain liquid acid and can be mounted sideways if necessary for installation in tight spaces or for easier access to the terminals.

While this may seem like a lot, wet cells have the following advantages.

They are usually less expensive than other batteries

  • Usually have a somewhat longer life cycle

* A major disadvantage of installing wet cells on boats is their vulnerability to boat vibration

fishing boat

Lithium-ion batteries - the newest addition to the battery world is proving to be a star, but be warned, this high performance battery is expensive. Lithium iron phosphate battery performance than the general energy storage lithium-ion battery, which has high temperature resistance, with a certain rate of high current discharge capacity. Aolithium LiFePO4 battery can provide 4000 cycles, a long service life. the BMS system can protect the battery very well.

Ordinary lithium iron phosphate battery low-temperature performance is relatively poor, but the improved lithium iron battery, in low-temperature performance is slightly better than nickel-metal hydride batteries, slightly worse than lithium polymer batteries, but the high-temperature performance will be reduced. In terms of installation costs, lithium iron phosphate batteries are more expensive than nickel-metal hydride batteries, and lower than lithium polymer batteries, so most of the types of marine batteries used are lithium iron phosphate batteries, because in the same room temperature applications, the use of lithium iron batteries are more cost-effective.

  • They are lightweight and carry a deep charge
  • They also have the longest life of any battery and can be recharged faster and more often over their entire life cycle
  • Lithium-ion batteries accept charging current five times faster than lead-acid batteries.

* If your passion for boating depends on high performance, it may be worth it to buy a powerful lithium-ion battery.


Gel Cells - Gel cells are filled with an electrolyte similar to a wet cell, the main difference being that the liquid becomes a gel. This eliminates the need to replenish the cell with water.

These cells are usually maintenance free and are more resistant to boat vibrations

They also have a fairly low self-discharge rate, which means they can be stored throughout the winter without frequent recharging

*The downside here is the cost and the need for special equipment. Gel batteries cost twice as much as wet batteries and require special chargers.

How to maintain your battery?

Installing your battery correctly

Batteries must be installed properly to provide safe and effective performance. I have lost count of the number of times I have seen many boat owners put batteries in place only by attaching the cables to the terminals. Aside from the stress this puts on the cables and terminals, it is dangerous. A moving battery can contact some metal part of the boat and cause a short circuit and start a fire.

All batteries should be secured in an acid-proof box or tray to prevent spillage. A box also isolates the battery from physical damage that could crack the casing and cause acid to leak. Positive terminals should also be covered. Most boxes have covers for this purpose.

The right way to charge

The best thing you can do for your battery is to keep it properly charged. If left, all batteries will self-discharge. The rate of discharge varies depending on the type, size and age of the battery. Lead acid batteries can lose up to 5% of their charge per month, so it is important to always charge batteries that have not been used for a while (for example, in the winter) regularly to keep them fully charged.


After the above comparison of the advantages and disadvantages of the types of lithium batteries for fishing boats, I believe that many fishing boat owners should know the appropriate type of lithium batteries to choose according to the operating characteristics of their fishing boats, in general lithium iron phosphate is a better lithium battery for fishing boats.

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