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Thread: DC motor control?

  1. #1
    Join Date
    May 2010
    Location
    Port Townsend, Wa.
    Posts
    915

    Default DC motor control?

    Short version: if I buy a 24V DC variable speed forward /reverse motor control off the web will I regret it? How will I regret it??

    I had been using a Minn Kota 24 volt trolling motor for an auxiliary. On the eve of the Port Townsend Wooden Boat festival it suddenly stopped doing anything (timing is everything). I eventually discovered that the motor still worked but that the black box of electronics was at fault, it has "no-user-serviceable-parts" and a replacement would cost about $500. I have been getting-by since then with a brutal knife-switch polarity reverse hack. Internet searches have revealed that there are myriad suppliers (mostly Asian) offering 24 volt DC variable speed motor controls really cheap, advertised at as much as 100amps (I need 50) for less than $100. Many of these seem targeted to the Battle-Bot crowd.

    So finally, here is my question: What about electronic noise, interference, FCC, VHF problems, corrosion in a marine environment, broadcasting Pulse Width Modulated 400 hz audio underwater at the poor whales, etc, etc.

    I haven't seen much in the way of compliance statements on these web sites.....

    Ken

  2. #2
    Join Date
    Feb 2007
    Location
    N62 5352" E27 4110"
    Posts
    400

    Default Re: DC motor control?

    I had a Minn Kota 80lb in my boat and fried the control after a season and a half. Then I purchased what you describe from Alibaba and eventually fried that as well. My problem (I think) was the hot environment where the control had to live. Now I am in my third Alibaba controller and I am constructing a proper fan-driven cooling for it and I hope it will last.

    I think the chinese controller is better than the original at least in one feature: since my motor is fixed (embedded) in the keel it started spinning its propeller at speeds above 4 knots. The chinese short circuits the motor when switched off with reverese - off - forward switch. Jammed propeller doesn't make noice and introduces less drag than rotating.

  3. #3
    Join Date
    May 2010
    Location
    Port Townsend, Wa.
    Posts
    915

    Default Re: DC motor control?

    Quote Originally Posted by Timo_N62.9_E27.7 View Post

    I think the chinese controller is better than the original at least in one feature: since my motor is fixed (embedded) in the keel it started spinning its propeller at speeds above 4 knots. The chinese short circuits the motor when switched off with reverese - off - forward switch. Jammed propeller doesn't make noice and introduces less drag than rotating.
    This sort of baloney makes me sad about innovation in my country: The Minn Kota Rep in Everett, Wa says he is regularly replacing solid-state control heads for these. They are potted in epoxy and if they were designed well, they should last forever. Meanwhile, for the past 20 years or more, "Inquiring minds" have wished that American industry would address electric motors for small boats. We have bolted model airplane propellors to small motors, and carved propellors out of small stacks of wood slats. We have made all kinds of experimental craft. I have been badgering Minn Kota for that long to make some propellors optimized for small boat propulsion rather than weedless-ness. American business has replied that there's no market. Enter Torqeedo and a crop of Asian companies, and guess what? There was A Puddy-Tat!! People will pay serious dollar while American business is still using brushed DC motors that haven't advanced since the 60's.

    grumble gripe piss and moan, maybe this belongs in the bilge...

    Ken

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