Old vs. new trolling motor efficiency, maximizer

[nsimms]

I have an old "Minn Kota 35" motor that is rated 17 lbs thrust. The "35" possibly refers to 35 amps (12 volt), as the chart on the top says 3.5 hrs at full throttle for a 105 AH battery (though I would think that would be more like 25-30 amps at that fast a discharge rate).

What few specs I can find for the current low-end motors say about 1 amp per pound thrust, full throttle. Is this any more efficient than the one I've got?

Is the Minn Kota 'Digital Maximizer' capability worth the extra money? I've yet to see any hard data regarding how much efficiency it gains, or even a real detailed explanation of how it's supposed to work. Does it increase range at full throttle? or more so at half throttle?

This is for a 17' wood and fabric Folbot kayak, about 100lbs, plus 400 for crew, and about 100 for motor and battery. The old motor gives me about 3mph on flat water, light winds.

I'm looking for something that might give a little more speed, and preferably more efficiency/greater range. If someone could confirm that the maximizer motors give significantly more range, I might be willing to pay the higher cost of one (I would also have to beef up my motor mount, as the old motor I built it for is quite light, while the smallest maximizer motor (40lb thrust I think?) is much heavier).

Thanks in advance for any advice/experience y'all can relate!

NS
Carrboro, NC

 

[JB]

Re: Old vs. new trolling motor efficiency, maximizer

The Maximizer circuitry regulates power to the motor by sending pulses instead of putting an extra load in series with the motor. To go faster it speeds up and lengthens the pulses until at full speed it applies all of the battery voltage all the time.

At low and medium speeds this saves a lot of power that would have been used to make the extra load hot, at full speed it makes no difference at all.

At half speed the Maximizer almost doubles range over non-maximizer of the same thrust. At full speed the range might be a bit less, but not much.

Bottom line? It takes power to make thrust. There is no free lunch. If you want to go faster you are going to use more power.

 

[Silvertip]

Re: Old vs. new trolling motor efficiency, maximizer

Motors with non-maximizer circuitry use what are called "speed coils" which are nothing more than wire wound resistors to reduce the voltage to the motor. When you do that the resistors must drop the extra current so they get very hot. Heat is wasted energy which is why the maximizer does so well at anything less than the highest speed setting. There is no waste with that system. At the highest speed setting, both styles of motors are fed 12V straight to the motor so there is not advantage other than more efficient windings and better magnets but that produces just a small increase in efficiency.