Motor controller voltage drop

[andrewAB]

I installed Sean's Tinypilot and motor controller along with Garmin/Jeffa Linear driver with builtin rudder sense 2 years ago and it works great.

This year I have had a few cases where upon powerup of the 12V master supply something happens and the 12V rail is limited to around 4V.  I have a small panel with digital voltage display on the circuit dedicated to the Pypilot so see this immediately.

I did some basic fault finding by disconnecting the components in turn and narrowed it down to a dicky connection between the motor controller and the drive.  Disconnecting and reconnecting the pins (soldered onto wires from the  motor controller output & clutch controller) into the linear drive socket and the fault went away.  Sometime later it came back then disappeared again. I have added some additional strain relief cable clamps either side of the connection and it seems good/better now.

I am puzzled at how a faulty connection between the controller + motor and clutch could cause such a big voltage drop at the supply board and not blow the 10amp fuse on the supply input on the motor controller.  There is about 15 feet of the 12V supply cable from my chart table supply (where Tinypilot is located) and the motor controller but the wire resistance should be negligible. All the connections look good. 

I am also concerned I may have damaged something in the motor controller.

Does anyone have any idea what may be happening here?

Thanks
Andrew

[seandepagnier]

Do you mean a bad connection from the motor controller to the motor, or from the battery to the motor controller?

A bad connection to the motor should only mostly limit motor output to a lower speed.

[andrewAB]

It is the connections between the controller and the motor drive that I disconnected and reconnected thst made the problem go away.   I am.not sure if clutch, rudder feedback or motor forward/reverse. Or could be coincidence.

I am wondering if there is something in the startup sequence or protection ciruits of the controller?  No idea really!

I was looking for some  partial short in the cable connections on the 12V supply into the controller as this was what I was thinking could cause a bit voltage drop on the supply.

[seandepagnier]

the motor controller has protection circuits for shorting out the rudder feedback for example if that is what you are asking maybe that was the problem?

[andrewAB]

I will take a DC clamp meter when I am next on the boat so I can see which cables are carry current if the faulty state happens again.

Thanks
Andrew

[andrewAB]

Mystery solved!
Found a dry Solder joint at the back of my 12v supply panel.

Fiddling the motor cables was a false clue - probably just some time between power cycles and the slight movement of the boat was enough to make a connection.

So I have alligator clip over the joint as a temporary fix until I resolder tonight.

The Clamp meter showed zero current on the supply cable and was easy to trace back to the source.