Resistor kit??? Evinrude 12/24 foot trolling motor

[BigBassin78]

I just bought a boat with an old evinrude trolling motor on it. It looks to be in great shape, however it seems that someone along the way tried to modified it with a resistor kit, as evidenced by, a resistor kit manual found buried in the engine manual. It seems that there are original parts missing in the foot control, and was just wondering if I could fix this. I have handbuilt a tube amp for a guitar, so I am handy with wire and solder. I just need a schematic or a good photo of an OEM foot control, or if someone has one sitting in the corner of their garage, whip it out and help me out. Thanks all

PS: first post!

 

[BigBassin78]

Re: Resistor kit??? Evinrude 12/24 foot trolling motor

This is a 1978 model, its the one that is a light powder blue. What is a resistor kit for?

 

[Silvertip]

Re: Resistor kit??? Evinrude 12/24 foot trolling motor

Older trolling motors used a combination of high current wire wound resistors to control motor speed. Through a network of series and parallel wired resistors, the combinations of which were selected with a speed selector switch, various resistance values were inserted in series with the motor POS lead thus controlling motor speed. These were not efficient motors since they used almost the same amount of current on low speeds as they did wide open which was a direct connection (no series resistor). If you are familiar with the old three speed fan resistors in car heaters of years gone by, the principle is exactly the same. If the switch has OFF, FAST, 2 and 3 settings, then only two resistors would be needed. One for #2 and another for #3. Those values would be quite low. The resistors need have high current carrying capacity because they dissipate a great deal of heat.

 

[BigBassin78]

Re: Resistor kit??? Evinrude 12/24 foot trolling motor

Well this didnt really answer my question, but thank you for that information though. I think that I am just going to bypass the whole circuit and create my own spring loaded switch, with one speed. As you said there was not much point to the lower speeds...

The foot controlled red switch that engages the motor is gone. So there is no way for me to press it to go, so can I buy this part somewhere or should I do what I just said? I hate to waste a good mechanical device, especially since the motor, mount, and foot control still works.

 

[Silvertip]

Re: Resistor kit??? Evinrude 12/24 foot trolling motor

Any heavy duty spring loaded, momentary switch will do but remember, it must be capable of handling high current loads. As for the resistor kit, that did not install in the foot control. It installed in the motor housing. The speed selector on the foot control merely selected which of the resistors was used. There is also a separate trolling motor switch called a BIg Foot (no relatiion to the Mercury Big Foot Outboard). This is a heavy duty switch that is placed in series with the +12 volt feed to the motor. The motor is switched ON (or wired permanently on) and the Big Foot switch is stomped on (figuratively) to function as the "go pedal".