I have a 24 volt trolling motor. The control board will not pass current to the motor. I noticed that the relay in the center of the board is a Tyco 12-volt 50 amp relay. When I turn on the motor I hear the relay click and I can feel it click when I put my finger on it. I have a new way to get power to the motor but I am just curious, is it okay that a 12-volt relay was in this 24 volt circuit? when I look at a picture of the control board on the factory website, it clearly shows a 24 volt 50 amp relay on the control board.

 

If the factory found a good cheaper source of 12V relays instead of the more costly and less abundant 24V, may have adapted/modified the circuit to run its coil with a resistor in series or something else. Check if there is something in series to the relay coil.
Most relays can be uncovered to inspect its contact points. Check their health and mechanism.

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Check wiring terminals for toasted, not tight connections. Re-crimp and solder. Done that to a trolling motor control, replaced the entire cable with those used to power car audio super amplifiers. Beefy, shiny and very flexible. Customer happy.

If there is forward/reverse control, two SPDT 12V relays with coils in series may be supplied by 24 V and do their job.

 

I've done the opposite - used a 24 volt relay on a 12 volt circuit. They WILL work, but sometimes they can be fussy.

I don't want to assume you don't understand how relays work but I want to cover what they do just to be on the safe side and to be sure you have this point down. Assuming you have a 24 volt motor and need to switch it on and off. You can do that with a switch. A relay is the same thing as a switch, but with an automatic part to it - the control coil. There are in fact, two parts to a relay, the coil - and the switch(es). When the coil is energized it creates a magnetic field which pulls an armature down, closing the contacts of the switch portion of the relay. The switches are completely independent of the coil. You can have a 12 volt coil that is pulled down by 12 volts of electrical power. This doesn't need to be a heavy current, it can be just a few hundred milliamps of current at its rated voltage. The switches can handle whatever they're rated for. In the case of automotive relays, they can control up to 40 amps of current (typically - but not universally). Some relays have a 5 volt coil that operates a switch that can control 240 VAC (Volts Alternating Current). So what the relay is rated for as far as voltage, it's independent of what the switches may be doing. In the case of your trolling motor, I suspect it's controlled by a 12 volt source (but I'm NOT the expert on water craft). The switches may be turning the motor on and off at much higher current.

What can go wrong with relays? Well, the coil can fail. But then the relay won't click (or you won't be able to feel it click). Another failure of the relay can be the contacts of the switch(es) can burn so badly they can no longer make contact. Is that what has happened to your relay? Actually no body here could tell for sure without doing some bench testing on it. In short and simple terms, you energize the coil and listen (or feel) for the click. You then check the contacts to make sure there is continuity between the C terminal (Common) and the NO terminal (Normally Open). And the NO contact is just that - normally open. It's only closed when the relay is energized. Hence, that can be what turns the trolling motor on.

Relays are pretty reliable. They don't often fail. They DO fail, but it's rare. In the case of your trolling motor control board I'd check for voltage (the full 24 volts the motor needs). It should be present at one of the two contacts (and many relays have more than two contacts, the other contact is called the NC terminal (or Normally Closed). It only opens up when the relay is energized). As I was saying, you should have 24 volts available at the (most likely) C terminal. When the relay is energized there should be 24 volts at the NO terminal as well. This indicates a normally functioning relay.

Relays come in many types. There is a sort that has 4 Common terminals, 4 Normally Open terminals and 4 Normally Closed terminals. I don't know what you have, so just keep in mind that your relay could be switching both the +24 volts AND the -24 volts. More than one relay and you could have two 12 volt batteries, and with one relay switched in the motor can run slow on 12 volts and with the second relay switched in the motor can run at full power (24 volts). Like I said, we can't tell for sure exactly what you have, so it's a lot of general comments and guesswork.

I'd look for the voltage coming into the relay; and with the relay energized I'd look for the voltage coming out as well. IF you have power passing through the relay then it's probably not the problem. If there is no 24 volts at any part of the relay then I'd guess that you may have a blown fuse. OR a catastrophic failure on the control board. I've seen bad solder joints cause problems, over current (actually under designed circuitry) cause the copper traces on the board to melt and fail. And finally, if you have a good 24 volts present all through out your circuit - maybe the motor has died. To be sure, you need to fully diagnose the problem before you can fix the right thing (or things). Yes, there can be multiple problems at play.

Good luck. Maybe take some pictures and post them so we can get a better idea what you're working with.