Selecting The Ideal Battery Size For Your Trolling Motor

Unlike other batteries a trolling motor battery has a thicker grid size for deep cycle usage and help offer better performance. Batteries produce a chemical reaction of sulfuric acid with lead plates to create a direct electric current. After which, sulfates are deposited on the plates, reducing their ability to produce a current.The grids represent how the anode and cathode are aligned. The network of the battery’s grid makes the charges flow to each terminal of the battery. They also have electrolytes in them which cause chemical reactions between the anode and the cathodes. Chemical reactions are responsible for forming the charges which a device using the battery exploits. All these previously mentioned components are placed inside a cell with a strong welded case which makes it durable and spill proof.So the importance of a good battery cannot be overstated.

Many fishing days are cut short, or an angler has to leave a tournament early because of equipment problems. Having a good battery is a necessity when going out on the water. When looking for a trolling motor battery for your boat, you want to consider the battery type, battery amperage hour rating, and your budget. Batteries have the greatest advantage which is; they apply to all devices, whether mobiles or automobiles. Trolling motor batteries are not similar to car or truck batteries since car and truck batteries which have a short-cycle and only need a kick-start to get the engine running in case of emergencies. These are cells which can withstand heavy duties and give a remarkable performance. They wear out after extended use; therefore, you need to be observant when considering which brand to purchase. A boat and jet skis are examples of motors that use trolling motor batteries.

Among all these factors to consider, choosing the right battery size is also particularly important. The question of choosing the right battery size for your trolling motor can be a bit confusing, but keep in mind that this step is crucial, and the wrong choice can have undesirable consequences ranging from poor performance to complete failure of the trolling motor.

Choosing the right battery size for a trolling motor requires the following four steps:

First, you need to calculate how much thrust you need from your motor; second, you need to measure to ensure you select the right shaft length; and third, you need to match the power output of your motor to the right battery or batteries;Fourth, after choosing the right battery, match the battery with the right size to create more output power.

The BCI group size is a term used to indicate the size and power of a battery. There are several groups of cells. Examples of the groups include 6D, 8D, 31, 27 and 24. Group 24 is the smallest and typically used for boats. Also, if you happen to have an old battery box ensure the new one also purchased fits in the box. Finally, ensure that where you place the battery, there is enough room and some ventilation. Electric trolling motors run on 12-volt marine batteries. Series of batteries can be linked together to provide additional power, depending on the model of trolling motor and it’s power. Two 12 volt batteries can link together and add 24 volts to the motor, and three batteries link together to add 36 volts to the motor.

Large motors require two or three batteries to meet the demand of 24 or 36 volts for the motor. They also provide more thrust. The longer and more consistently you fish will depend on the size of trolling motor and battery you will need.

Typically, trolling motors that deliver 55 pounds of thrust or less need a single 12V battery. As you step up in power to motors that are rated to as much as 80 pounds of thrust, expect to power them with two 12V batteries. And for the most powerful trolling motors generating more than 80 pounds of thrust, you’ll typically need three 12V batteries to run them.

  • 55lbs of thrust or less = 12 volts (one battery)
  • 68-80lbs of thrust = 24 volts (two batteries)
  • 101-112lbs of thrust = 36 volts (three batteries)

The trolling motor you buy will be labeled as a 12V, 24V, or 36V motor, indicating how many 12V batteries it requires.

There are three types of batteries for your trolling motor:

Wet-Cell Batteries

They are also known as deep cell marine batteries. They are relatively inexpensive and, are tough enough to handle constant drains and recharges. They do require some maintenance, topping off the water. They usually last between 1-2 years.

AGM Batteries

AGM stands for Absorbed Glass Mat. They are built using a glass plate and gel-like substance. They are enclosed so you won’t have to open them up to add distilled water. They cost up to two times more than a wet-cell battery but last longer, usually between 3-4 years.

Lithium-ion Batteries

They can last a relatively long life if kept at a temperature of under 105 degrees. They can last up to 10 years, but expect to pay the most money for these batteries. They can cost from anywhere between $850 to $1,500 per battery.

You have purchased the type of battery that works best for you, and then when you get home and look at your boat and see that there is a battery compartment just waiting to be filled, you realize that the battery you bought won’t fit. What’s going on here?

The basic standards for battery size are set by an association called Battery Council International (BCI). It is simply a trade committee that represents the interests of lead battery manufacturers, and “group sizes” are just general guidelines for battery sizing. But to say that it is a rough standard would be an understatement, especially considering the following:

It is designed for lead storage batteries, it specifies maximum dimensions rather than actual dimensions, and battery manufacturers use these numbers as a very rough guide.

Let’s look at common marine battery Group Sizes:Group Size – Length – Width – Height

  • 22NF9-7/16”5-1/2”8-15/16”
  • 24M10-1/4”6-13/16”9-3/4”
  • 259-1/16”6-7/8”8-7/8”
  • 27M12-1/2”6-13/16”9-3/4”
  • 31M13”6-13/16”9-7/16”
  • 34M10-1/4”6-13/16”9-7/16”
  • 359-1/16”6-7/8”8-7/8”
  • 6512-1/6”7-9/16”7-9/16”

As you can see, as the Group Sizes get bigger, the batteries get bigger, too. As crazy as this is, Group Sizes don’t match batteries’ dimensions in real life!

Unfortunately, the maximum dimensions for group sizes are not indicative of actual size, and battery manufacturers usually don’t adhere to these “guidelines”.Even worse, in real life, batteries in the same group vary so much in size that they may not even fit in the space labeled for them.

So remember, once you find the right size trolling motor battery, keep it safe. Always remember to charge the battery, this protects the life of the battery. Storing discharged batteries will reduce their performance. Never mix different types that have been placed together during storage. If a wet cell is stored somewhere in the battery, the other cells should be wet as well. Do not store old batteries with new batteries either, as the old batteries will pull the new batteries down. Wet batteries need to be checked regularly for fluid levels and always replenish them with distilled water. Using distilled water prevents tap water from destroying the chlorine in the battery.

Remember to store your batteries in a cool, dry place and trickle charge them. If you do not use trickle charging, be sure to charge your battery monthly. Always keep the top of the battery clean and free of corrosion. If you notice signs of corrosion, clean the battery with baking soda and water or with a brush only.

Two or three batteries are required whenever there is 24 volts and a 36-volt motor is running. In this case, be sure to always connect the batteries in series; this means that all cells need to be attached to each other. When connecting, the positive cable from the motor should be connected to the positive terminal of the battery first. The final step in fully connecting the batteries is to connect the negative terminal of the first cell consecutively to the positive terminal of the next cell.

Buying boat batteries shouldn’t be difficult, and it shouldn’t be confusing to choose the right battery size for your trolling motor. Hopefully, this article will help take the confusion and stress out of the equation and help you find the right size trolling battery you need.

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