24 volt trolling motor for a 1448

[Fadec]

Hi folks. Wasn't sure whether or not to post this under electrical or motor topics, but any how I am getting ready to pull the trigger on a Alumacraft 1448 NCS. I live on a horsepower restricted lake and rather then put a 9.9 hp on this new tinny I was thinking about getting a transom mount 24 volt 80 lb thrust trolling motor.

I really like the idea of electric only (nice and quiet!). Plus I already own a 9.9 if it doesn't work out.

Do you think 80 lb thrust is overkill? I'm really not concerned about the cost or extra weight of an additional battery.

Fadec

 

[wmk0002]

I'm no expert, but I'd say as long is is variable speed, as in not the standard 5 speed version, then it is perfectly fine. You can set it pretty low and it will push you around fine and then you can bump it up pretty good for moving spots and for trolling.

 

[perchjerker]

it will be fine

Its better to power down a big motor than to stress a little one. Your batteries will last a lot longer between charges as well

 

[ahalls]

Question - when you say his batteries will last longer - is it because he will get a larger motor or that it is 24 volt? I am debating between a 55 pound 12 volt set up vs an 80 pound 24 volt system for my Smokercraft Promag 161...would i get better run time on the 55 pound if i hooked up two batteries in parallel or an 80 pounder 24 volt set up? Thanks!

 

[riverrat717]

This may help you understand. Best info for trolling motors I've found https://www.trollingmotors.net/blogs/selection/86933703-trolling-motor-thrust-guide

 

[richg99]

Nice site. Thanks for posting it.

I didn't find a specific discussion of two batteries on a 12-volt connected in parallel.. 55 lb thrust versus two batteries running a 24-volt series connected ..80 lb. thrust system. I did find this quote..

"In order to approximate how long a certain motor will run on the water, you simply take the battery's amp hour rating and divide it by the amperage draw. For example, for a motor that pulls 20 amps at medium speed using a 100 amp hour battery, the run time would be: 100 amp hour rated battery / 20 amp draw = 5 hour run time"

I would have thought that they'd be equal......

However, THIS discussion says different, due to the efficiency of a 24 volt trolling motor's windings.

https://www.bassfishin.com/bassfishingforums/showthread.php?s=75cacc58154a8a68a14ad503dbe93b03&t=22238&page=2

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"Okay, ...let me stop trying to talk in laymen's terms. If I start talking about coulombs, people's eyes are going to glaze over.

current x time = charge

I admit, I was incorrect in my choice of the word "energy"...it was too hastily typed.

current x time x voltage = energy

I never said this was Ohm's Law.

Ohm's Law is the defining principal in determining resistance losses.

If you run a 12V motor, you will have half the voltage, but twice the current of a 24V setup. Once again, this is for different voltage motors of the same thrust rating. The two-battery connection (series vs. parallel) does not matter.

What does matter is the resistance of the wires to the trolling motor, and the resistance of the windings in the motor itself. This is where Ohm's Law, V = IR (for DC only) comes into play. Resistance losses are based upon the square of the current:

power = voltage x current = I*R*I = I^2*R

When you double the voltage, you halve the current, but the resistance losses in the wire change by a factor of 4; i.e, only 25% of the resistance losses in a 24V system vs. a 12V system. This is what provides extra running time to a 24V system vs. a parallel battery 12V system.

I don't really need to Google it.

I taught circuits at the college level, and I'm an Electrical Engineer.

This topic is closed as far as I'm concerned."
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