
How to Calculate Trolling Motor Battery Runtime
, 5 min reading time
, 5 min reading time
You’re out on a boa, ready for a relaxing day on the water when suddenly, your motor shuts off. The most common explanation for this is your battery running out of juice; as common and horrible as it is, it’s a highly preventable scenario that many experience, even boating veterans. Understanding how to calculate your trolling motor battery runtime can help you better plan your trips and prevent any unwanted battery drains.
The first step to calculating battery is to identify and understand the different concepts that are laid out. Even if you’re experienced in this regard, refreshing your understanding of these key concepts may be a good idea. In either case, staying informed and understanding the different key concepts is crucial to calculating the battery runtime.
The battery capacity is measured in what is known as amperage hours, or amp hours (Ah). Amp hours refers to the amount of energy a battery can store and provide, or charge and discharge, over a specific period of time. Higher-capacity batteries have longer run times when compared to batteries with a lower capacity. LiFePO4 batteries have a 100% discharge, meaning that if the battery states that it has 100Ah, all 100Ah can be used before charging as opposed to others, such as lead-acid which only have a 50% discharge rate before charging.
The trolling motor power use or draw is the amount of energy it takes to turn it on. Typically, this is measured in watts (w), and will typically be found on the manufacturer’s website, instruction manual, or on the motor itself. Sometimes, instead of watts, it’ll be measured in amps. If that’s the case, and you need to find the wattage number, you can multiply the amps (a) with the volts (V) to find it.
Volts are the measurement of electrical voltage, or how much “force” there is to push electricity through. Knowing a motor’s voltage is crucial to creating a battery system as the volts must be compatible. Simply put, if a motor is 12V, then the battery system must also be 12V, or else the system won’t run properly.
When you have the wattage, amperage, and voltage of the motor, you can then begin to calculate the runtime of your motor. The formula for estimating the runtime of your motor is as follows:
Runtime (hours)=Battery Capacity (Ah)×Battery Voltage (V)/Motor Power Consumption (W)
For example, let's say you have a system that is 12V with a 100Ah 12V battery and a 500W motor. To determine the runtime (hours), you would take the battery capacity (100Ah) and multiply it with the battery voltage (12V); then you would divide the result by the motor power consumption (500W), making it look like something like this:
Runtime in hours =100Ah×12V/500W
The resulting answer is 2.4 hours of run time under ideal conditions. This doesn’t take into account other factors that can affect the total, including the boat's weight, other electrical appliances, wind and water resistance, speed, battery age, and other external factors.
To ensure the maximum and most efficient battery runtime for your boat, follow these tips:
Understanding how to find your battery’s runtime and the separate factors that go into it will help you better plan for your trips on your boat and make more informed decisions regarding motor upkeep. Sunrich Energy’s line of LiFePO4 batteries is perfect to keep you from having to worry too much about your motor runtime. Take a look and find on that’s right for you.