Trolling Motor Amp Draw

[River Rocket]

I put a lithium battery in the boat recently. I bought Relion 24V 50Ah from Tim Powell. I originally had 105Ah on two 12V AGM batteries. I have been concerned that I may have undersized and needed 2 batteries. I have done a lot of research and the ratings and stats numb my head. To settle it I got a new battery gauge for the boat. I had a gauge from Stealth that gave both the starting and the trolling motor voltage, but I wanted to know what my current draw was while running. Relion makes a gauge, but I didn't want to drop $100 on answering the question. I ended up finding the gauge that Relion private labels for $40. The gauge gives the voltage, % charge, remaining amp hours, and current draw.

Installation is pretty easy. You need to install the shunt on the battery and run the supplied cables. Luckily I have a odd battery setup and when I made all the changes I put trolling motor posts for the 24V way up in the nose. I installed the shunt on those so the cable they provide would be long enough.

Here are the results for those that are interested. This is a 24V Minnekota 80lb trolling motor.

I have a Terrova, so as soon as the motor is deployed it must turn the main board on and begins to draw a small amount of power. As you can see it isn't drawing anymore power than speed setting 1. I use the remote that beeps every time I increase the speed. I took the boat out on a wind free day and recorded the amp draw and speed at each setting. The amp draw fluctuates a little, but you can see its a clean step. The speed also jumps and the gps doesn't have a lot of resolution down low, so the information may not be 100%.

I typically run between 5 and 7 with short bursts up to 10. When run between setting 5 and 7 I will get between 15 and 31 hours of use.

With the Stealth charge while driving and the new Mercury V8 alternator I should never have an issue running multiple days without 120VAC.

I'm not trying to sell any one technology. I just thought I would share potentially useful information.

Amp Draw 2.JPG

[NOTGSXR]

Nice

[CatFan]

You can’t easily measure the current on a variable speed TM. It always draws about 40A and is switched on and off rapidly to vary the speed. No meter will give any kind of remotely accurate measure of power consumption except on max speed. To actually determine power consumption you’d need to capture the current waveform and integrate to get something like average Watts.

[River Rocket]

Thank you. The tech guy at the battery company didn’t mention that when we discussed this. Good to know.

It is interesting the the current has very clear and clean breaks. That does explain the jumping number better. I knew the digital feature of the motor would do something, just didn’t realize that is how it Worked

On the plus side I have a gauge that is viewable in direct sunlight now.