All Things You Need to Know about Lithium Trolling Motor Battery

Throughout the ages, fishing has been a leisure and entertainment for people to relax their bodies and minds. With the significant improvement of the level of science and technology, people no longer stick to fishing in rivers and lakes. People yearn for excitement, and in the face of the endless and rough sea, more and more people want to explore. To go out to sea for fishing, equipment is very important. It goes without saying that fishing gear, boats and trolling motor for hauling fish must be prepared. Because trolling motors are very important, and batteries are the core components for trolling motors, thus we will introduce batteries in all aspects today.

So, let’s begin


What is Trolling Motor?

A trolling motor includes an electric motor, propeller and controller. And trolling motor is attached to the bow or stern of the angler. A gasoline-powered outboard motor used for t rolling. When the ship’s main engine is running, the trolling motor is usually lifted from the water to reduce drag.

Application of Trolling Motor

Mainly used for fishing: installed on the beam next to the main outboard motor or on a bracket manufactured for this purpose as an auxiliary means of propulsion.

As an auxiliary power, the trolling machine is used to accurately manipulate the ship, which enables the angler to accurately cast the bait at the location of the fish. Traction motors designed for this application are usually installed in the bow.

What is a Lithium Trolling Motor Battery?

What we said about lithium trolling motor battery is refer to lithium iron phosphate(LiFePO4) deep cycle battery which can provide steady power to trolling motors. Usually, what specification of battery we need for a trolling motor is 12V, 24V and 36V. And of course, how many volts of a battery you need depends on the model of trolling model.

For a 36V trolling motor, you could use a single 36V battery. And in fact, we always use three 12V batteries connected in series to meet demand. For a 24V motor, you could either use a single 24V battery or connect two 12V batteries in series. Lastly, for a 12V trolling motor, just one single 12V battery is enough. And you can multiple several 12V batteries to add battery capacity of the whole lithium battery pack. According to this way, the run time of lithium trolling motor battery pack can be prolong.

Why do We Choose Lithium Battery as Power Source of Trolling Motor?

Nowadays, there are many kinds of batteries, for example, lithium battery, gel battery, lead-acid battery and etc. As we all known that, longer run time is one of advantages of lithium battery. Generally speaking, a lithium battery can provide two times longer of run time than that of lead-acid battery and lithium batteries will not experience the power drop traditional deep-cycle batteries experience as the battery drains. And lithium battery have a longer cycle life, better efficiency and lighter weight and etc. BMS is also built in lithium battery. Let’s dig into each of these more.


BMS is the abbreviation of battery management system. Basically, a power supply system composed of more than two single batteries requires a BMS.

The function of BMS is:

  1. Monitoringall parameters like current, voltage, temperature and etc.
  2. Dividing these collected information into different parts like overcharge current,discharging and Charging in high temperature and etc.
  3. Storing these information and then provide to user.

Compared with lithium battery, because of lacking BMS, lead-acid batteries can have internal short and it will be damaged from high temperature and low temperature. And it will even suffer from the effect of improper charging.


At present, the service life of lead-acid batteries is about 2-3 years. Generally, after one year of use, the navigation ability will begin to decline significantly. The life span is short. It is necessary to pay frequent attention to the battery situation so as not to affect the fun of fishing. The service life of lithium batteries is 4-5 years, and the battery life attenuates less with the extension of the service life.


The battery life is mainly related to the voltage and battery capacity. As lead-acid batteries repeatedly go through charge and discharge cycles, they can never be fully charged to their capacity. Over time, they slowly wear out until the voltage drop mentioned above is too great. Then the battery can’t power your motor any longer, even on a full charge.

Lithium batteries don’t last forever, but they typically last for five to ten times as long as lead-acid batteries. This is because of their flat voltage curve and how they’re built. Lithium batteries have the advantage of being a true deep cycle battery with minimal degradation to their lifespan. Unlike all lead-acid batteries that get damaged with each deep discharge, minimal degradation to the life cycle will occur if you use them up each time.


The current energy density of lithium batteries is generally 200~260wh/g, and lead-acid is generally 50~70wh/G. Then the weight-energy-density lithium battery is 3 to 5 times that of lead-acid. This means that with the same capacity, lead-acid batteries are 3 to 5 times that of lithium batteries. Therefore, lithium batteries occupy an absolute advantage in the lightweight of energy storage devices.

For boaters, boat weight is a big deal because craft’s handling and performance will be impacted by the total weight of boat equipment and passengers in a boat. Thus, lithium batteries which are about one third of the weight of a regular lead-acid marine batteries can easily solve boaters’ questions.


Combing lighter weight and longer runtime of lithium batteries, you will finally get a much more efficient system. The depth of discharge for lithium battery is 100% which means lithium battery can provide full power and regardless of charge level. Trolling motors need a fail amount of cranking thrust because trolling motors usually experience sudden speed fluctuation.

When you are selecting your trolling motor, this question is common:

How Long Will Trolling Motor Run on the Water?

To approximate trolling motor runtime, battery capacity(Ampere hour) and motor amperage draw are key parameters.

Ampere Hour

Marine batteries are rated according to an indicator called “ampere-hour”, which indicates how long the battery can provide a consistent amperage. The larger the rating, the more power the battery can hold, and the longer it will take to power the motor at a given speed.

For example

A 120 amp-hour battery can provide 30 amps of power for 4 hours before the battery runs out (30 amps * 4 hours = 120amp-hours).

Alternatively, the same battery can also provide 12 amps of power for 10 hours before it dries up (12 amps * 10 hours = 120 amp-hours).

You can think of the ampere-hour rating as similar to a fuel tank in a car-the larger it is, the more energy/fuel it can store, and the longer it can power the electric motor.

Motor Amperage Draw

The second factor we need to calculate the estimated running time is the motor current consumption. The current consumption rating of a motor refers to how much current (or current) the motor consumes at a given speed. The exact current rating of the motor is not always easy to find, but it should be available from the manufacturer. In order to estimate the time a certain motor will run on the water, you only need to divide the ampere-hour rating of the battery by the amperage.

For example:

for a motor that uses a 120 amp-hour battery to pull 30 amps at medium speed, the running time is:

120 amp hour rated battery / 30 amp draw = 4 hour run time

for a motor that uses a 50 amp-hour battery to pull 40amps at medium speed, the running time is:

50 amp hour rated battery / 40 amp draw = 1. 25 hour run time

If you do not get accurate amperage draw, you can approximate calculate runtime by Watts. You then compare this to the AH rating on your battery.

For example:

For a motor that uses a 50 amp-hour battery to pull 600Wh 12V trolling motor, the running speed is:

600Watts draw/12Volt battery=50amps draw

50Ah/50amp draw=1 hour

Note: Water and weather conditions can significantly affect battery performance. The motor that moves the ship at a medium speed under calm conditions consumes 25 amps of current. It may take 35 amps of current to move the same ship in strong winds or waves. If you plan to use the motor frequently in windy or stormy conditions, you need to include it in the calculation.