Calculating battery power life per charge over a given distance

[Aquadust]

Hi

I am trying to find out how much battery life I need to power a motor for a given amount of distance but I am struggling to make sense of it all. I know from a product I have disassembled that it has a 270W motor with 2 x 24v 24A batterys and it will travel up to 11 miles.

I will be using a 180W motor and have to cover 8 Miles in distance but according to my equations I will need the same amount of power even though the motor being used uses less power.




They equations I have are P= VxI also rearranged gives I=P/V to give me the amps required.

I also tried using J=FxD but I am certain this is wrong in terms of what I am trying to achieve.

I=Current
V=Voltage
P=Power
J=Joules
F=Force
D=Distance


This makes 180/24 = 7.5Amps. the speed it will travel at is between 2-4 MPH so if i use 24v and 24AH batterys it will travel they 8 miles in 2 hours at 4 miles an hour or 2 1/2 hours at 3MPH but any slower say 2 MPH and the battery will not last long enough?

this is based on the motor using 7.5 amps per hour or 7.5aH. So 24aH diveded by the 7.5 = 3.2 hours. This gives how long the battery will last for but the speed will be varied for this application.

Any help with my problem would be much appreciated.

Many thanks in Advance.

 

[KataKoniK]

Hello,

Thank you for reaching out with your question. It sounds like you are trying to determine the battery life needed for a 180W motor to cover a distance of 8 miles. Based on the information you provided, it seems like you are on the right track with your equations. However, there are a few things to consider when calculating battery life for a motor.

First, it is important to note that the power of a motor is not the only factor that determines the battery life. The efficiency of the motor, as well as the terrain and conditions in which it is being used, can also affect the battery life.

That being said, your calculation of 7.5 amps per hour for a 180W motor is correct. However, this does not account for the efficiency of the motor. If we assume a conservative efficiency of 80%, the actual power consumption of the motor would be 180W/0.8 = 225W. This means that the motor would require 9.4 amps per hour (225W/24V) from the battery.

Next, to determine the battery life, we need to consider the capacity of the batteries. You mentioned that you will be using 2 x 24V 24AH batteries, which gives a total capacity of 48AH. Dividing this by the current required by the motor (9.4 amps per hour) gives a battery life of 5.1 hours. However, as you mentioned, the speed at which the motor is traveling will also affect the battery life. At a speed of 4 MPH, the motor would require 9.4 amps per hour, giving a battery life of 5.1 hours. At a speed of 3 MPH, the motor would require 7.05 amps per hour, giving a battery life of 6.8 hours. And at a speed of 2 MPH, the motor would require 4.7 amps per hour, giving a battery life of 10.2 hours.

In summary, to cover a distance of 8 miles with a 180W motor, you would need a battery with a capacity of at least 48AH. However, the actual battery life will vary depending on the speed at which the motor is traveling. I hope this helps with your calculations. If you have any further questions, please don't hesitate to ask. Best of luck with your project!