Trolling motor amp draw at diff speeds??? Trolling motor amp draw at diff speeds???
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    Trolling motor amp draw at diff speeds???
from Mike (  
8/23/2006 6:37:00 AM


 The boys have been debating this issue for quite some time and need some resolution. On a trolling motor without the maximizer or dura amp feature is there a difference in current draw at different speeds? Will the batteries last longer on speed 1 compared to speed 5??? Also, do the OMC motors have a feature like the maximizer on them? Foster, please help us resolve this controversy!

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   Amp Draw from Foster's Trolln Motor Repairs-Sales  8/23/2006 8:01:00 AM
 YEP!! Speed motors are built with a coil inside the motor.This coil has a series of wires placed in varies places to act as a resistor when the switch is switched to a perticular position.The slower the speed position,the more resistence. The faster the speed position,the less resistence.The slower the speed position,the less amps it will draw,the faster the speed,the more amp draw.Just about like your car,the more you press on the accelerator for speed and power demamd,the more gas you'll burn and vise versa.

Foster's Trolln Motor Repairs-Sales

   Wait a minute.... from Mike (  8/23/2006 9:24:00 AM
 Foster, For example a minn Kota without the maximizer. Does it not draw the same current regardless of the speed???

   Correct from Foster's Trolln Motor Repairs-Sales  8/23/2006 10:48:00 AM
 If you look on the top cover ov the Endura,5 speed,you'll see that at a lower speed it will extend battery much longer that at high speed.Theres a scale on the cover that estimates battery life at different speeds.Lower speed has the longest battery life.

Foster's Trolln Motor Repairs-Sales

   So the from tornthumb  8/23/2006 12:23:00 PM
 Maximizer thing is a sales gimmic and not needed? I`m getting ready to buy a new 24v. Tim

   Wrong from Foster's Trolln Motor Repairs-Sales  8/23/2006 1:47:00 PM
 The Maxximizer in the Minn Kota is an electronic circuit board that pulses the motor on and off very fast so you don't notice it.By doing so it saves the battery life and extends fishing time.Without it,like the 5 speed motors,it would just be continiously drawing amperage.

Foster's Trolln Motor Repairs-Sales

   Motors from MWood (  8/23/2006 2:01:00 PM
 When it comes right down to it, all motors use current to generate a magnetic field. There are a number of physical variables used to determine the strength of the field generated by the motor windings (such as wire size, number of wraps, etc) but once these physical parameters are determined, they can't change....they are fixed. The only single thing that can change is the current through the motor winding....which, along with the permanent magnet, determines the rotation strength. The more current applied, the stronger the field and the faster the motor will turn. What the "maximizer" does is a mystery to me....probably nothing more than a fancy term for current limiting, just like the resistive coils, only done descretely. Is it better than coils? Foster's could probably make a call on that issue better than I could. My guess would be that the coils waste power by generating heat and the descrete components do not...but again, I'm guessing.

   Maximizer from MWood (  8/23/2006 2:17:00 PM
 Thanks Foster's... that makes sense. I was kinda wondering how the digital portion of some of these new motors worked. Are they using stepper motors or conventional motors for newer TMs? Enquiring minds and such...

   Amp draw from Buddy (  8/23/2006 6:08:00 PM
 Fosters is correct about the Maxximizer pulsing the current. So Tornthumb I have to disagree with you. It definitely is not a gimmic. I bought one of the first ones to come out about 20 years ago. It made my battery last a lot longer. A conventional 5 speed motor uses resistance to vary the speed. In speed 1, the motor uses 20% of the amps from the battery and the other 80% goes to the resistor, like MWood said, and is dissipated as heat into the water. That is one reason you shouldn't run a motor out of the water. In speed 4, 60% of the amps go to the motor and 40% to the resistor. So you are using 100% of the battery at all times regardless of the speed setting you are using.

The Maxximizer pulses off and on extremely fast. In speed 1 it pulses so fast that it is only on 20% of the time. Hense the slow speed. In speed 5 it does not pulse and is on full time. When your battery is only on 20% of the time, it WILL last longer. In the original Maxximizer you put your motor in the number 5 speed and used the Maxximizer's variable speed knob to control the speed of the motor. I like today's built in units a lot better.

   thanks for the from tornthumb  8/23/2006 6:27:00 PM
 clarification. Now to find the best price on the MK maxximizer. Tim

   surely you don't mean a resistor from Fatboy (  8/23/2006 6:35:00 PM
 A resistor would draw as much or more amps / volts than having no resistor or running wide open. It also would heat up hotter than a 2 peckered Billy goat. I canít recall the name for what I think you are talking about but if it only limited the amount of volts going to the motor without causing resistance / heat then of course it would use less energy on a lower speed.

   Agree with Buddy from Mike (  8/23/2006 8:58:00 PM
 That was my understanding 100% but Foster does not agree and he knows his trolling motors. But again I have read on many sites, even in Minn Kota's brouchers, that what Buddy says is correct.

   Pulse width modulation from Spookchucker (  8/23/2006 9:32:00 PM
 The Minn Kota maximizer & Motorguide's version use pulse width modulation, which in simple terms are square waves instead of DC. For instance, on a 24 volt system you lose voltage thru the motor, and that loss is a constant, lets use a 4 volt loss as an example. That means at full speed on a conventional model, you run on 20 volts, 4 volts are lost, remember? Half speed would need 10 operating volts which means you need 14 volts of throttle, or 58% of throttle for 50% speed. With pulses, all pulsed are 24 volts, and only the width of the square wave changes. Higher speeds make the square wave wider at the top, staying on longer. Since you are now using 24 volts for all speeds,you only need 50% throttle to run at 50% speed. 50% vs 58% would mean 16% more efficient. and the slower you go, the more you save. At 20% speed on a conventional motor, you need 8 volts, or nearly 40% throttle for 20% speed, with PWM, you only 20% power for 20% speed, so your batteries would last twice as long.

   Battery Life from MWood (  8/24/2006 9:29:00 AM
 Sorry Buddy...conventional TMs have the resistive coils in series with the motor windings. If the TM motor winding needs 5 Amps to move at the desired speed, then the whole circuit only draws 5 amps from the battery. If you want to go faster, you lower the resistance of the coil and more current flows through the coil and the motor winding at the same rate, which at full speed could be greater than 20-25 Amps.The resistive coil regulates the current draw through the motor. So, as Foster's said, if you go slow, you use low current and your battery lasts a long time. If you increase the speed, the coil resistance is dropped and more current is provided to motor winding decreasing the life of the battery.

   MWoods is correct from Foster's Trolln Motor Repairs-Sales  8/24/2006 9:41:00 AM
 I jsut try to put into laymens turms that most people can understand.Spookchaser is right too,but it hurt my brain to read it.Sorry Spook,but the regular guy can't understand what you're trying to explain.Like I always tell myself,"KEEP IT SIMPLE".

Foster's Trolln Motor Repairs-Sales

   correct but from MikeF  8/24/2006 6:26:00 PM
 The problem with the resistive type TM contollers is that you have power consumed by the resistor in series with the motor. The term is I2R loss. If you draw current through a resister then you generate heat. That's power you are drawing from the battery but not using for propulsion. That's why the older TM's had the 12 24 switch. It takes less resistance to limit the current flow from 12V. So yes the TM draws less current at lower speeds but it still draws more power from the batteries than it uses for propulsion. That's why they went to Pulse Width Modulation. The on period of the pulse is varied from 0 to 100% to vary the speed. It's not perfect but it's way more efficient than heating up a resistor.



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