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how to wire two 24v motors to a joystick

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mjkkemper

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Hello all

I am trying to figure out the best way to wire to 24 volt 56 Amp (Max) motors to a joystick approximately 20 feet away. When I hit the joy stick to the Left I want the left motor to be in reverse and the right motor to be in forward. Reverse the process of when the joystick is to the right.

What this is for is I am mounting two 80lb thrust Minn Kota motor to the transom of a boat for a Stern thruster. (see Diagram)

Here is my questions given the AMP draw (56) the wiring to the motor needs to be a large gauge.

I would need to use - a contactor - A solenoid - How do I wire it so that the joystick wiring is control wiring and I can use heaver gauge wiring to the motors?

Also I would like to minimize current drop so I do not think I would wire the batter power all the way up to the joystick and then back down to the two motors to power/control?

Is there any control/circuit boards out there I could use for this purpose?

I did not draw in any wiring in that I was looking for feedback. Please let me know if you need additional information

Thank you in advance

Matt
 

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user_88

Member
Do you want proportional control with the joystick, or simply off and on ... according to your directional requirement?
 

user_88

Member
Suggestion A ... economy approach :
What about using automotive starter solenoids arranged in the H bridge controller configuration? ....Then run a 12 or 14 gauge wire from the control point ... 20 ft. away.
That would mean a total of 4 solenoid units for each motor.

You would also need an industrial grade joystick.

... Probably add a couple of circuit breakers or fuses to the motor current wires.

Auto starter solenoids are rated for 200 or 300 amps ... momentary contact. However, with only 56 amps, they should last longer.

The alternative is to go with higher priced industrial contactors.
 

4pyros

Well-Known Member
Most Helpful Member
That would mean a total of 4 solenoid units for each motor.
No just 4 total. Wire one motor the opposite of the other and run both thru the same H bridge.
 

user_88

Member
No just 4 total. Wire one motor the opposite of the other and run both thru the same H bridge.

That might work. The two motors would be in series ... However if motor winding heating, and subsequent resistance increase were significant, you would lose power/torque output.

... Difficult to say, without experimenting, whether two independent H bridges would give a significant improvement.
 
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4pyros

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Most Helpful Member
That might work. The two motors would be in series ... However if motor winding heating, and subsequent resistance increase were significant, you would lose power/torque output.

... Difficult to say, without experimenting, whether two independent H bridges would give a significant improvement.
Not series. Wire them in parallel with the opposite polarity. Controlled by the same H bridge.
 

mjkkemper

New Member
what type/make of contacor would i use?

also i would only be using this for short durations like 30 seconds

lastly if i switch between forward and revese would i need any type of delay?
 
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user_88

Member
what type/make of contacor would i use?

also i would only be using this for short durations like 30 seconds

lastly if i switch between forward and revese would i need any type of delay?


... Type of solenoid or contactor would require some additional research ... would probably depend on your project budget ...

One additional concern would be the instantaneous full power condition that would be generated by activating the motors. There is a rotating propeller effect called cavitation, which occurs when you exceed certain conditions ... kind of like spinning your tires, except with a propeller in the water.

It might be a good idea to devise some sort of partial or stepped speed control. Maybe several coils of heavy copper wire would create an inductance, that would retard the maximum current buildup for a short period of time.
... Again ... calls for a little experimentation, if you can afford it.

... Regarding the previous idea for using parallel wiring of the motors through the H-Bridge ... I concede that it would work. However you would double the current magnitude flowing through the solenoids ... over 100 amps. I suggest that a conservative design ... with a longer life ... would use two separate H bridges, one for each motor.

If I was going to build this, I would find a well stocked auto salvage yard, and get a set of 8 identical auto starter solenoids. Then construct a working circuit that will actually get your motors turning. At this point, you can determine if you need to worry about a delay, or stepped control ... or whatever else. ... Proof of concept would be a big step forward.
 
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mjkkemper

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4pyros

Well-Known Member
Most Helpful Member
Whether or not you will need 4 or 8 will depend on if the ones you get can take the load of both motors.
 

Diver300

Well-Known Member
Most Helpful Member
What about a reversing Soleinoid? below is a link

https://www.surpluscenter.com/item.asp?item=11-3169-24&catname=electric

Would I just need two of these?

Also these are 100amp but i have two 56 amp (max) motors.

You would be best with 2 because you would otherwise be overloading the solenoid slightly.

They are only rated to a 20% duty cycle, and 6 minutes continuous at 100 A, but that shouldn't be a problem for what you want to use it for.

I think that they would be ideal.
 

mjkkemper

New Member
You would be best with 2 because you would otherwise be overloading the solenoid slightly.

They are only rated to a 20% duty cycle, and 6 minutes continuous at 100 A, but that shouldn't be a problem for what you want to use it for.

I think that they would be ideal.

I downloaded the wiring diagram from the site. One is the origanal and the other is with two motors.

Is this the correct way to wire it?
 

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4pyros

Well-Known Member
Most Helpful Member
I downloaded the wiring diagram from the site. One is the origanal and the other is with two motors.

Is this the correct way to wire it?
Yes thats it. Good find on the reversing Soleinoid. You only need 2 now not 8!
 

user_88

Member
Glad to see that you have the hardware selection narrowed down ...
I am curious to see if you have any undesirable fluid dynamic effects at the propeller, due to the full power switching of the fluid directions ... also from standstill.
These would be cavitation, surge, or maybe something else. You may have to give some thought to a delay or stepped power control if this is the case.
Just guessing at this point though.
... Would like to hear how it turns out....
 
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