Thread: 24V verses 12v for trolling motors

Originally Posted by MDCrappie

Hence the reason he asked what the advantages are of each.

With 12 volt he only HAS to buy one battery initially, he only HAS to carry one if he doesn't need the capacity. (Some boats only have room for one battery)

The 24 volt motors do have higher available thrust options but other then that I can't think of any advantages off hand.

I switched from a 12 volt 55 pd thrust to an 24 volt 80 pd thrust. My motor now only works about 60 percent as hard as the 55 did to maintain 1.7 mph when pulling cranks. This is a huge advantage when u are wanting to fish for long periods.

Originally Posted by Handicrappie

I switched from a 12 volt 55 pd thrust to an 24 volt 80 pd thrust. My motor now only works about 60 percent as hard as the 55 did to maintain 1.7 mph when pulling cranks. This is a huge advantage when u are wanting to fish for long periods.

OK so you've stated the same advantage I did - Higher available thrust.

But I think if you find out how many amps your motor is drawing and divide that by the # of available A/H you will see that you are going to get just about the exact same run time as the 55lb motor with the same 2 batteries.

Looks like a lot of people are trying to compare electric motors as they do gasoline motors. (ie 50hp at WOT vs 80hp at 3/4) Not quite the same

I dont totally understand all the data involved but I know that I only ran one battery and got about 3.5 hours and would switch to another with the 55. Now with the 80 I've ran over 8 hours a few trips and was still going strong when I quit. Go with the 80 if you plan on running 2 batteries in my opinion.

Thank you all for the info, not really sure which way I will go yet. But thank you all for your responses. Everyone here is very helpful.

if the batterys arnt the same age the weaker one will pull the newer one down,when i ran 2 batteries(12volt) i used a quick disconnect so i only had one battery hooked up at a time instead of wiring them together.now i have 2 24 volt setups(4 batteries)in my boat,added another plug up front so i can switch setups pretty quick,if u ever start trolling u will run down your batteries,if u dont troll you will probally be alright.

Originally Posted by MDCrappie

Hence the reason he asked what the advantages are of each.

With 12 volt he only HAS to buy one battery initially, he only HAS to carry one if he doesn't need the capacity. (Some boats only have room for one battery)

The 24 volt motors do have higher available thrust options but other then that I can't think of any advantages off hand.

Energy used in an electrical circuit is expressed in watts. Watts is the result of Voltage times current. Thus a 12 Volt motor using 2 amps is using 24 watts. Now a 24 Volt motor only uses 1 amp to produce the same 24 watts. In DC circuitry remember P= I X E
Power is Watts or P in the equation 24 watts= 2 Amps X 12 Volts
Current is Amps or I in the equation
Voltage is Volts or E in the equation 24 watts= 1 Amp X 24 Volts
So in terms of current load for the same power rating 24V is more efficient than 12V.
In simple language yep 24v trolling motors are more efficient that 12v motors so spend the extra money.

Originally Posted by blueball

if the batterys arnt the same age the weaker one will pull the newer one down,

Just another reason why (IMHO) the 12volt set up is better, when you have batteries that aren't exactly the same.
The "capacity" of batteries changes with age, and even though 2 batt's might initially be equal they will degrade at different rates.
Say you have a batt at 100 a/h and the other at 50. If you use the 50 (in a 12 volts set-up) then disconnect and use the 100 you get a total of 150. Since the 24 would have used 1/2 you get a total of 75 a/h for comparison.
If you put both of those (50 and 100) together in series to get 24 volts you will only get a total of 50 a/h out of the pair (weakest link).
So in this instance the 12 volts set up will give you another 50% run time.

Another 12 volt advantage is the initial cost of the motor, 24's can be quite a bit higher.

Originally Posted by strmwalker

Energy used in an electrical circuit is expressed in watts. Watts is the result of Voltage times current. Thus a 12 Volt motor using 2 amps is using 24 watts. Now a 24 Volt motor only uses 1 amp to produce the same 24 watts. In DC circuitry remember P= I X E
Power is Watts or P in the equation 24 watts= 2 Amps X 12 Volts
Current is Amps or I in the equation
Voltage is Volts or E in the equation 24 watts= 1 Amp X 24 Volts
So in terms of current load for the same power rating 24V is more efficient than 12V.
In simple language yep 24v trolling motors are more efficient that 12v motors so spend the extra money.

How did you come up with "efficiency" in your equation?

If the 24 volt motor is more "current" efficient (requiring less current), then the 12 volt motor is more "voltage" efficient. (requiring less voltage)