Wednesday, November 10, 2010

Power Resistor versus Mamba Max

The round black thing (as we call it in the trade) above is the resistor or I think maybe even reostat (probably just jumped way out of my league here) that normally lives inside the head of a Minn Kota motor unit. Apparently it reduces motor speed by complaining and whinging and making a fuss, with a result that the battery gets really bored and feels a bit flat well before it should.

These, on the other hand are pictures of MAMBA MAX, who just rolls over and cons the motor into doing less work by tickling it or something, and in the process the battery stays interested for longer. Combined with a neat little thing with the disturbing name of a "Servo Tester", it will also allow me to turn the motor on (in good 1960's fashion) and also make it go backwards.

As a bonus, I've put it on my teak CB case top for decorative purposes to make this post look more useful than it probably is.
There are also efficierncies that can be improved by using different impellers, or propellors. Apparently model aircraft ones are very efficient, but they don't cut weeds as well...I'm going to avoid that one for the moment, because it is very easy to get carried away with experiments, forgetting that it's just about going for a sail after all...

The mamba max thing (SKU16184) is from Castle Creations, which I found at


  1. One quick question: Does the trolling motor lower unit have two or three wires powering the motor? The controller you are listing is for a "brushless" motor, which is basically a 3-phase AC motor. If your motor is a simple DC motor, that unit will not work for you.

    To give a slightly simplified description, a brushless motor is controlled by feeding power to the three leads in a rotating fashion. To reverse the motor, the power "rotates" the other way. How fast the power "rotates" determines the motor's speed.

    A brushed motor is a COMPLETELY different beast. It is "fed" with DC (direct current, or non "rotating") to the motor's two leads. It's speed is controlled by varying the voltage going to the motor, which is probably what the resistors in the old control provide. To reverse it, you simply reverse the polarity (connect the battery backwards).

    An ESC for a brushed motor usually uses PWM (pulse width modulation). This means turning the motor on and off very rapidly (usually several thousand times per second). The ratio between the "on" times and the "off" times is what determines the speed.

    Best of luck with your project!

  2. I feel like an idiot. I just looked closer and that ESC can be configured to run a brushed motor. It should work just fine. You will just need to make sure it is configured for a brushed motor.

    God bless!

  3. Thanks for your input Wayne, and keep up the good work on your project too.

  4. Well...That's all very nice and thank you for the confusion. And people tell me that trimming sails is too much effort!
    May I ask about that pretty fiddle-head in the background? (you might be sorry you asked me over for a visit soon). She seems to be missing some tuning pegs. Had that problem myself one time.

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  6. That instrument in the background is a very sorry cello that someone thoughtfully 'repaired' with epoxy. No longer economic to fix because of that. Whole belly rebuild required and the owner hasn't enquired further, so it takes up space next to the bandsaw where I should be standing in relaxed comfort while using that machine...
    Well, a long time ago I once got legless, but never pegless...

  7. Hi Rob,
    Following with interest as I to have been tossing around an electric drive for Coquina (shock horror) still have not convinced myself to chop a hole yet.


  8. Hi Mike. That's certainly the hard bit! But you can always fill it in later....