rheostat on Motorguide or Minn kota

[stratosjoe]

Was wondering if there was a way to install a rheostat to make any trolling motor a varible speed. My MG tour on low is still pretty fast. Just curious

[Wayne P.]

Was wondering if there was a way to install a rheostat to make any trolling motor a varible speed. My MG tour on low is still pretty fast. Just curious

What Motor Guide Tour do you have that is not variable speed?

[stratosjoe]

tour 70 has 1 thru 5. What I am saying is a true variable speed slow, slower than 1

[Wayne P.]

tour 70 has 1 thru 5. What I am saying is a true variable speed slow, slower than 1

Variable speed is just that, variable from no RPM's to max RPM's.

[Bradrodfish]

Was wondering if there was a way to install a rheostat to make any trolling motor a varible speed. My MG tour on low is still pretty fast. Just curious

that would be a no. That motor is a 5 speed and the speed is controlled by windings in the foot. Those windings have to have a 24 volts or 12 volts. Lowering the voltage to the troll motor is asking for trouble with wiring. That is what a rheostat will do.

[Larry3215]

Actually, the speed is electronically controlled by a "speed controller" in the head. Reostats are nothing like a speed controller and would not work in this application.

Speed controllers vary the pulse width of the power going to the motor. The voltage the motor sees never changes - its just switched on/off very rapidly. The speed controller changes the ratio between ON and OFF cycles to vary the speed. A reostat varies the voltage while leaving the power on full time. Totally different animals.

Those pulses are where most of the sonar interference comes from.

[Jonestrollingmotor]

Actually, the speed is electronically controlled by a "speed controller" in the head. Reostats are nothing like a speed controller and would not work in this application.

Speed controllers vary the pulse width of the power going to the motor. The voltage the motor sees never changes - its just switched on/off very rapidly. The speed controller changes the ratio between ON and OFF cycles to vary the speed. A reostat varies the voltage while leaving the power on full time. Totally different animals.

Those pulses are where most of the sonar interference comes from.

Not quite correct but close. The rheostat in the trolling motor controls the resistance (I'm talking Motorguide since that's what the OP has) to the module located in the lower unit. As that resistance changes, the module increases or decreases the pulses to vary the speed -- unless it's a hand operated, in which case the rheostat still controls the resistance but at a certain level, it changes the relays located on the brush card to reverse the current and make it go in reverse. This, on a digital motor, is apx 2.5K. For this reason, 0 to 2.5 is one direction and 2.5 to 5K is the other direction. At any rate, it is rheostat controlled, but not as the OP was thinking.
Now, to the OP, you can purchase a PWM speed controller, place the trolling motor and high and wire the PWM into the wiring going to the trolling motor and get a variable speed motor. don't know the cost of doing this as this is an aftermarket "fix".
John

[stratosjoe]

thanks to all for the responses, You don't know if you don't ask.