Selecting POT and 3-pos switch for custom Minn Kota EM44 trolling motor control - Page 1
Forum section: electronics / beginners

author: caegear
author_rank: Contributor
timestamp: June 27, 2016, 11:00:34 pm
content: Hello all,I have a Minn Kota EM44 trolling motor that I want to control by putting a pot and a forward - stop - reverse switch inside my allready working outboard engine controller (standard Teleflex / ultraflex).The teleflex control operates the outboard by transferring my physical manipulation of the throttle to the engines speed and gear knob respectively. When I push the throttle forward, the mechanical control puts the outboard in its "Forward" gear, and increases speed. If I pull the throttle back to neutral, the mechanical control sets the outboard to "Neutral", and speed to idle. If i pull the throttle backwards, the mechanical control sets the outboard to "Rewerse" gear, and increases speed. So. One gear knob (F - N - R) and one speed knob (0 - 100%) on the outboard is operated by magical rotating disks inside the mechanical control coloumn, so that my forward and backward movement of a single lever switches gear and increases speed. All is god.EM44My EM44 is originally controlled by a hand held wired remote control that is connected to what I suspect is a good quality PWM. The motor itself is 12vdc. I have not found any information on this from Minn kota, but I have seen larger thrust motors (58LBS. Mine is 44LBS) is using some 30A under maximum load so I am assuming my motor draws under 30A at maximum load.I dont have the hand held wired control, but I have found a service manual on a Dutch site that tells me the six wires in the cable for the control is: 3 wires (orange, green, brown) going to POT that does 0-1K ohm, and 3 wires (yellow, black, white) going to Forward - neutral - Reverse switch.The hand held wired control costs some 100USD, and since I want to not use it and instead build its functionality into my exixting teleflex, I want to find a POT and a 3-position switch to use instead.I gather i need a POT that is 1K Ohm, and probably any fairly capable 3-position switch, but I cant find any meaningful information on what watt / amp rating my POT and switch should be. Googling and reading a little leads me to believe that the POT and the switch does not need to be able to bear the full load of the motor itself (its probably 300 - 400 watts @ 12vdc), but most POTs i find on eBay are rated both in Ohm and Watts, and I would love to get som helt in deciding what Wattage if any I should try out. I am guessing any "standard" will do, but for all I know it is fatally important to select the correct wattage rated POT...Second thing I would love to have some input on, is a simple relay switch that I would like to install on the power supply (12vdc) going to the EM44. EM44 is mounted on the anti cavitation plate of my outboard, and it only needs to be "live" / controllable when the main Outboard is NOT running. I figure It should be fairly straight forward to put some kind of relay / diode-ish automated switch on the wire(s) going from the engine to the battery for sensing if the main outboard is running (and outputting current to the battery bank) or not, and if Yes: Cutoff power to EM44 / if No: Run power to EM44.Since Im rather new to this, I dont know if this kind of Relay-thing is a common gadged or a stupid, unheard of, impossible madman-thought, so be kind... :)See attached picture of wires / pin assignment for the EM44 hand held wired control and images of the control itself and the PWM / main unit.

author: tautech
author_rank: Super Contributor
timestamp: June 27, 2016, 11:13:12 pm
content: Quote from: caegear on June 27, 2016, 11:00:34 pmIMO the wired control will include the control box in the image and that does all the work so just replicating the wired handset and expecting it it to do it won't work.

author: caegear
author_rank: Contributor
timestamp: June 27, 2016, 11:26:32 pm
content: Quote from: tautech on June 27, 2016, 11:13:12 pmI agree. I should have explained that I do have the main control board / box. Its just the little housing with the pot and the 3-pos switch that I dont have :/Im only replacing the POT and the switch, and Ill be wiring it to the main board / box (PWM and / or Buck regulators / fuses aso most likely)I took a picture of the inside of the Main board / box and have commented in red what wires goes where, and attach a larger image of the wiring description :)

author: tautech
author_rank: Super Contributor
timestamp: June 27, 2016, 11:50:00 pm
content: Then you should be fine. For a saltwater environment I'd take care in selection of parts and/or methods to protect them, if your helm is covered that will make it easier.You might be wise to select a wirewound pot for durability.Basic componentry for this project need not be high current rated as it's only working at control signal level values.

author: caegear
author_rank: Contributor
timestamp: June 27, 2016, 11:58:52 pm
content: Quote from: tautech on June 27, 2016, 11:50:00 pmOh. Thank you so much! I will try out a 1K Ohm Wirewound pot and try to find (or seal myself) a standard 3-pos switchAny thoughts on a sensor / automatic relay that I could use to sense if Outboard is sending charge to batteries and if Yes: Dont send power to EM44 / if No: Send Power to EM44 so that the EM44 "seamlessly" is engageable whenever main outboard is not running?Is this a common sensor? Does anyone know what it might be called and / or where I might find more information on such an automated relay switch (without going into Arduino:)?

author: tautech
author_rank: Super Contributor
timestamp: June 28, 2016, 12:16:47 am
content: Does your main outboard have keyed ignition?If so: key on , no power to Minnkota, key off, power to Minnkota.Little relay in series with the center pin of the 3 position switch on the Minnkota remote should work fine.

author: caegear
author_rank: Contributor
timestamp: June 28, 2016, 06:52:04 am
content: Quote from: tautech on June 28, 2016, 12:16:47 amOf course! :) that is a great idea! I love this "half mechanical" stuff for durability and simplicity.Thank you so much for your help Tautech! In my book time is the most valuable thing we have while buggering around on this planet, and you giving me some of yours, is really good of you :)

author: tautech
author_rank: Super Contributor
timestamp: June 28, 2016, 07:34:26 am
content: Quote from: caegear on June 28, 2016, 06:52:04 amYep, simple and elegant and meets the KISS principle.You're very welcome, thanks for the gratitude.

author: caegear
author_rank: Contributor
timestamp: June 30, 2016, 06:49:48 am
content: So. Ive made a sketch trying to illustrate implementation of seamless engagement of the Minn Kota EM44 when main outboard is not running (and not starting). In this sketch Ive put the relay directly on the main power cables to / from motor to simplify wiring (my brain needs this to be simple). I dont think there is any real difference in this sketch and if I wired the relay on the ignition (step 2 (running motor) on ignition would go in on 86 and out on 85) and then pulled center wire on 3-pos switch through 30-87a, other than this sketch does not give current to PWM unless the Outboard is not running (or starting?). If wiring directrly on main cables, Im kind of monitiring regulator / charge controller inside Outboard. If wiring on signal cables / ignition, Im kind of monitoring both PWM components and ignition switch and motor electronics and would have a larger amount of wiring and components to error-correct if anything stops working after relay? After all, there should not be any current flowing on main cables unless I turn on starter solenoid using Ignition, or the motor is delivering charge to battery because it is running...If my sketch looks sound, would it be better to wire A or B? Will any of them (A) create a separate circuit that is Allways Closed (allways running current through 86/85) and mess up my desired seamlessness or is there no practical difference since the Relay has a directional diode and the coil itself inside Relay isnt drawing current on its own?

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2016, 11:31:51 am
content: Here's what I thought, between us you'll get the picture and make something that's workable.The other thing that might be worthy of investigation is the quiescent current of the controller and an isolator may be needed to prevent battery drain.NoteNC on the relay terminal is NO CONNECTION not normally closed.

author: caegear
author_rank: Contributor
timestamp: July 01, 2016, 06:13:14 am
content: Quote from: tautech on June 30, 2016, 11:31:51 amI feel like Neo staring at those raining pulsating strings of Matrix source code. Slowly but surely they make sense and the crylic greenish chaos turns into meaningful, logical facts that I can interact with and actually use to my benefit :)Thank you so much! Ill update this thread once POTs, relays and switches arrive and I have a setup that I can take some pictures or video of :)