Hello guys! I'm painfully new here and especially new with electronics and coding.
I could use some guidance on what is possible and what is not possible.
Project outline
I am trying to build a steering mechanism and power control (in fwd/reverse brushless motor) for a trolling motor on a boat. This system will have a wired remote control so I can stand and fish.
What I know
I plan to use a servo and the arduino "knob sketch" with a joystick I saw on adafruit with a 4.8V rechargeable battery pack to control the steering of the trolling motor. I tested my circuit and the code on a hobby test servo and feel as though with a little tinkering I can get that down by myself. The servo was a bit jittery but I put a cap & diode across them motor and messed with the time delay and it smoothed it out.
I intend to run an experiment to ascertain the size of the servo necessary. Once I calculate the torque necessary I can decide if I need some sort of geared power transfer or if I can slap a servo straight to the top of the trolling motor shaft. If the latter is not possible, I may come back and ask about "continuous rotation servos".
What I do not know
I don't know how to approach the fwd/reverse biasing of the motor and control the speed let alone write all the code for it. I found an h-bridge motor controller online but don't know anything about it and would hate to buy something without knowing if I can even use it.
My best guess is I'll need the H-bridge to control power flow but then use a pot to control the speed of the motor. There is also the option of getting a dpdt switch and controlling power that way but then I don't know how to control motor speed or if there are affordable switches that can handle an average 15A+ load. Nor do I really want hold a remote control drawing 15A through it.
Trolling motor specs
Max load 20A
Average load at full speed 15A+
need 12VDC power source such as a motorcycle battery.
Hello,
The device that you put a link to can handle a maximum continuous current of 13A, so if your motor needs more, then you will need to find one that can handle the rated current.
A H-bridge is a good choice for both controlling the direction, and the speed at which the motor is going.
It is called a "H-bridge" because the circuit looks like a capital "H".
The direction is changed by alternating the leg of the H-bridge through which the current is flowing.
The speed of the motor is controlled by controlling the duty cycle of each leg of the H-bridge. This can be done using "pulse width modulation" technique, frequently shortened to PWM. You will most likely find that the H-bridge contains 4 MOSFETs, 2 for each leg, or direction. The shorter the duty cycle (the on time) of these MOSFETs the less current will be supplied to your motor, and the slower it will go.
Hope that helps!
Note: you can't control a brushless DC (BLDC) motor with a simple H-bridge. You will need a brushless motor controller that matches your brushless motor. Some brushless motors have sensors to provide position feedback to the controller and some controllers sense the position from the windings themselves. That's why the controller has to match the motor.
Very informative, thanks.
I will have to do a lot more research on this one I think.
Here is the schematic for the motor https://cdn.shopify.com/s/files/1/0191/7628/files/2013-N-Minn-Kota-freshwater-motors-transom-endura-C2-Endura-C2-30.pdf?11138724384140476734
The motor uses some sort of analog rheostat to control what's going on. If I wanted, I may be able to use another servo to control that rheostat but it seems like that would be odd and clunky.
At the top of the PDF you linked to it says 12v 30 amps. I suggest you look for a 60 amp speed controller to give yourself some leeway.
From the diagram I think it is a simple brushed DC motor.
I suspect some of the speed controllers sold by, for example, HobbyKing may be suitable and economical. They can be controlled by the Arduino as if they are a servo.
If you arrange for the Arduino to operate a DPDT relay you would not even need to buy a controller with reverse capability.
...R
Robin2:
At the top of the PDF you linked to it says 12v 30 amps. I suggest you look for a 60 amp speed controller to give yourself some leeway.
If you arrange for the Arduino to operate a DPDT relay you would not even need to buy a controller with reverse capability.
...R
Thanks for the input. The manufacturer states that 30A is the absolute max load but anything that large is excessive when in real world tests this motor does not draw any more than 18A at any one time.
i will look into the DPDT relay but does that incorporate speed control or only fwd/reveres control?
Relays are just electrically controlled switches.
The reason I suggested a 60 amp controller is because your controller needs to be able to handle the stall current of the motor which is usually very much higher than the max running current.
A speed controller with an over-current or over-temperature cut-out would be a good idea.
...R
Kind of strange that the schematic shows four wires going from the control box to the motor pod but the parts diagram doesn't show anything in the motor pod except a brushed DC motor with two brushes. I wonder what the other two wires do. They could be current sense wires but no current sense resistor (or wiring) is shown in the parts diagram.