24v or 12v motor? Info right from the Manufacturer

For those contemplating a 12v or 24v motor, it seems that, contrary to what some believe, "Bigger" is NOT always "better".


There was a "Discussion" contained within a post "debating" the Advantages of buying a 12v motor vs a 24v motor.

I presented my thoughts on Run Time, but they were countered by several members and the post was closed.

I emailed Minn Kota the below information (same info I had presented in the post) and they got back to me with the reply that is posted at the bottom. It seems the folks at Minn Kota AGREE with my theory on the amount of run time with a 12v motor and 2 batts vs a 24v motor and 2 batts.

This is what I sent to Minn Kota:

Hello,
I'm looking to get a Riptide transom motor and not sure which is best for me. I know that I will never need more then 55lb thrust, but every one says to get 24volt as they have more "run time". From my figures below I don't see how, if I have 2 batteries for either motor, this could be possible. I could see it if the comparison is having just one battery with the 55lb and two batteries with the 80lb. I see that the 80lb model has a max amps draw of 56. If this is where 80lb is produced then I am guessing it will take about 38 amps to produce 55lbs. (56/80) to get amps/lb then multiply by 55 to get 38.5amps If I get the 80lb and (2) 100A/H batteries I figure I could run approx. 2.63hrs (100/38). I see that the 55lb model has a max amp draw of 50amps. If I get the 55lb model and (2) 100A/H batteries I figure I could run approx 2hrs (100/50) on each battery for a total of 4 hrs. (vs 2.63 with the 80lb) I know that batteries will degrade and I will likely never get the full 100A/H out of them, I just wanted to use round numbers for equal comparison. Are my figures correct? Since I will never need more then 55lbs thrust and the 55lb model is cheaper then the 80lb can you tell me if there are any other advantages to getting the 80lb model?

Awaiting your reply Thanks - Rob

This is the reply I receive back today:

Rob-

Thank you for your inquiry to Minn Kota. I agree with everything you have figured out as far as run time and differences between the 55# and 80# motor. If you run a 55# motor with two batteries as apposed to an 80# set up on 24 volts there is not doubt you will get more run time out of the 55# motor. As long as the boat is not too much weight for the motor to where you will be running it on higher speeds the whole time I would go with the 55# motor. That motor can efficiently handle a total weight (boat, motor, gas, gear, people, etc.) of 2700 lbs.

Thank you,

Marc Collins

Johnson Outdoors

Here is the initial post:
http://www.crappie.com/crappie/mecha...ng-motors.html

Thank you Rob for the information and clarification from MINN-KOTA. Eric

You miss the point tho. You aren't comparing apples to apples, no where close. I ran a 55 pound minn kota on a 17 foot glastron pulling cranks using 2 large 12v batts. Doing everything I could do to conserve juice I would only get 5 hours tops in good conditions pulling at 1.8 mph. With the same boat an 80 pound was pulling it for over 8 hours maintaining 1.8.
I ain't no lectriction or nuttin but 8 hours is more than 5 here on Mississippi.
Hands on practical application is where it counts.

I had a 170 lowe 55 lb edge mk. one battery would not last all day in the wind and went to 2 bats to make it. Now have 80lb no comparison and its on a G3 176 alot heavier rig and i run it less than half of what I would have with a 55. a 55lb thrust on a 2700 lb boat would work ok if you had a calm day and were fishing in your backyard sitting on your trailer, my boat will run 3 mph with the troller would never go to anything smaller

Im going to explain this real simple once again since Rob keeps leaving the voltage part of the equation out in his figures. A 24 volt motor only uses half the amps to produce the same thrust as a 12 volt motor. Since it only uses half the amps as the 12 you must double the 24 volt run time to make this equation correct which puts it at about 5.3 hours compared to 4 hours for the 12 volt in parallel. This all has to do with resistance as the more voltage you have the less resistance you have and therefore the more efficient the system. Please refer to the formula from crappie101 and the reserve capacity info from the article off the western bass site.

You're wasting your time, Handi. :banghead:

Cane Pole explained this theory a few years back on a post also.

Here it is broken down in simple terms again. This is simple enough for anyone to comprehend. And by the way, bigger is better.

Minn-Kota also told me, a few years ago that I needed 2 lbs. of thrust for every foot of boat, so therefore the 40lb thrust I had at the time should have been plenty on my 17 footer,NOT.just saying

1) your goober at MK is mistaken.

2) as long as you leave the V out of ohm's law you are never going to get it.

3) again, them AH's don't evaporate on that second battery in a 24v system.

4) I noticed that you never commented the other night, on my post referencing your own calculations showing more wattage output at lower amperages using 24v.