Fuse in a MK Troll motor? I may have toasted my Trolling Motor

[sam am I]

I haven't watched the video (yet) BUT!! I have an idea as a work around for your dead 12/24V relay feed!

So if the low side (dynamic PWM/neg toggling side) is still working (cross fingers) then lets just make our own 12/24V high side!!

Just remove the motor's red feed wire (switched 12/24V) off the controller board and tie it directly to 12/24V....Hit the pedal!!

Like I said, if the PWM low side is still PWM'ing, she'll spin up as normal....

So sticking with the original intent of the design...(I think they turn off the motor's 12/24V feed with the relay as a safety thing. In the event of a PWM failure that shorts to ground, the motor would be stuck in full out freaking s**t the bed run mode and you could crash and burn)

If that above test works, crack open the relay from the top side (surgeon style), fish out (add extension wire too) the relay's coil + feed wire that is still making the relay click and we'll add your own 100% functional external relay(use the 12/24V we made as a test plus the coil + and ground) and WE STUCK IT TO THE MAN!! Love being cheap too!! That's probably the best part.

 

[charly1954]

You said,"Just remove the motor's red feed wire (switched 12/24V) off the controller board and tie it directly to 12/24V". In the video that is what the guy did but with the motors Neg wire instead of the motors Pos wire. So essentially is that the same as what you said to do but with the Pos wire.

I'm no electrician so a lot of the things you talk about are over my head, especially the last paragraph. If the motor red feed test you describes works I really don't follow what you said in the last paragraph after cracking open the relay.

In you opinion, if I had a 50amp breaker between the battery and the battery lead to the control board would it have stoped the damage. As a layman I don't see how it could have stopped it because the arc that damaged the relay was from the pedal pins, the relay would have been between the pedal plug and the breaker. Since I couldn't find one in my town I ordered one on ebay today. It has a manual push button to throw the breaker or kill power , I like that features because I wanted to add a quick disconnect but with that feature I don't need one I just manually throw the breaker when I'm not using the boat.

 

[sam am I]

From earlier and if I'm correct in assuming your MK controller board is similar to the one I link too in #11 above.........

A general overview of how they work is....The control board manages among the other things, the motor's power AND ground. It does this actively and BOTH of which must be present in order to turn on the motor. Both are detailed below

1) Power.....12/24V (12V and/or 24V depending on the design type)

1. The motor's 12/24V is controlled by the relay. To turn on the relay(make it click) it requires a "run" signal present on the relay's control coil. The run signal is initiated by twisting a throttle or pushing a foot pedal. Once the relay receives this run signal, the relay's contact closes and supplies the necessary 12/24V to the motor until the throttle or pedal is released . Basically, the battery voltage coming onto the control board is just sent right back out if you press the pedal. The red wire obviously is this feed out as it leads off of the controller board terminal to the motor head.

2) Ground.....0V (But only some of the time, PW % = Ton/(Toff + Ton)) * 100)

1. To control/vary the speed of a DC motor(one of the ways), this controller uses a rapid turning on and off of the ground to the motor with transistors(Pulse Width Modulation or PWM).To go Slow'ish = 90% off and 10% on, Fast'ish = 10% off and 90% on. Unlike the power side (high side) described above which is either all the way on the second the pedal is pushed, or off with released, this side (low side) varies the speed just like your cars accelerator. The further down you press the pedal, the higher the % the pulse width(see equation above where Ton = time on and Toff = time off).

Lets guess #2 is working and if it is, we make our own #1. Why? Not only is it a safety feature I believe, we can hear the relay click, BUT! You measured no voltage coming out.....

To check this, it is a simple test, just hook the red wire to 12V and hit the pedal!!

If that test works, we MIGHT be able to steal the "run" signal by gutting it out of the old relay as it sits on the board. We know the "run" signal works (because we can hear it running the relay) and we could hook it to our own relay!!

 

[charly1954]

Hey Sam
I tried the test you said(motor head POS wire directly to battery POS) and when either pedal pushed nothing on the prop. I also tried what the guy in the video said(motor head NEG wire directly into batteryNEG) and nothing on either pedal. So it looks like the only way the prop will run is with a new board or wired directly into the battery pos/neg and it will be full power unless I add a speed control.

After that I tried a few test with multimeter. I have no idea what the results mean or if they mean anything. One test didn't make since, the motor head board pos/neg terminals show 12.4v right when either pedal was pushed but immediately drop volts way below 12v in 20 seconds and no prop movement .

The results below the motor head wires where pulled and battery wires where pluged into the board.

 

[charly1954]

…….To control/vary the speed of a DC motor(one of the ways), this controller uses a rapid turning on and off of the ground to the motor with transistors(Pulse Width Modulation or PWM).To go Slow'ish = 90% off and 10% on, Fast'ish = 10% off and 90% on. Unlike the power side (high side) described above which is either all the way on the second the pedal is pushed, or off with released, this side (low side) varies the speed just like your cars accelerator. The further down you press the pedal, the higher the % the pulse width(see equation above where Ton = time on and Toff = time off)…...

That right there is why the saying" you can learn something new everyday" is right. Speed adjust happens when current is turned on/off and a rapid speed.. I always thought voltage was decreased, now I know.

 

[sam am I]

Hmmm, controller board probably bad, dang!.......I'd be inclined to go re-check just the motor one last time. Hook that puppy up straight to 12V and ground. If she runs, guess our goose is cooked.


unlessssss.............

https://forums.iboats.com/forum/boat...te-to-find-one

Think that potting will come off easy???

 

[charly1954]

Didn't mention that but I did and the prop ran like before. I'll probably tinker with it a little more and post back if any change but I doubt that'll happen. And I'll be keeping an I online sites like ebay for anyone who has my model selling for junk parts, never know someone may have a control system that works but busted shaft or motor.

Thanks sam for all the great help and input I really appreciate you taking the time on this.

 

[sam am I]

No problems and glad to have been involved, I'm always interested in this type of stuff. If I'm not too careful, I usually tend to learn stuff....

 

[charly1954]

Hey Sam

I finally got around and opened the relay, had to use a hot knife my dermal drill couple went bad. I am no electrician but to me it looks like its just a coil serving as a magnet to put the contact point down. The points were a little burnt I cleaned them and still nothing. You said for a slow speed the power to the motor pauses on/off and the higher the speed the less it pauses. So I assume the contact points open/close fast to get the pauseing and someother part makes it pause, is this right. If that how it works then maybe something else is bad and not the relay. I added a photo, kind of blurry my cellphone does not take good closeups.

 

[sam am I]

Cool.....Nice cross section cut!! Impressive........


So recall from #23 above that the relay, when(or if) it clicks on, is turning on the 12V solid to the motor when you hit the pedal/throttle, the other half is..........The ground side of the motor,

Recall also the ground side is where the PWM circuits are switching slow and fast. The design uses transistors as switches to accomplish this fast/slow switch of the ground.

 

[charly1954]

I guess I'll just never understand unless something besides the relay is the problem. What I was getting at is to me it looks like there's no damage to the relay unless its underneath where I can't see it. It looks like a simple coil magnet which pulls down the points and makes contact which should put power to the motor. There's only one contact point which I assume is the Pos. side and there's no Neg side in the relay so something else must be stopping the motor from starting.

Been watching ebay and nothing showing up yet that looks like mine board. Think I'll start watching for clearance or sales on MK's Edge 55lb, it looks like its their cheapest at under $500. Maybe I'll part it out, the used V1 pedals are selling for around $100, the motor does work and also the compass and steering gears.