Replacing 24V trolling motor.. need ground?

[VaBass328]

I bought a new Maxxum 24v volt bow mount trolling motor to replace a an old Evinrude 24v Trolling motor. All of the wiring for a 24v is present (the next part may sound stupid, but I want to be sure). I have the recess tray for the pedal control and I wanted to hook up the wires underneath, eliminating the plug. The only problem is I have a ground (white) run to the plug....can I connect the red and black permanently under the hull while leaving the ground attached to the plug, even though I will not be using it? I am definitely not an electrician, and I definitely dont want to harm any of my equip. I would leave the female part of the plug intact with the ground (white)..but the other two wires will be attached underneath the deck. I guess I will turn off the unit on the foot pedal.which I "think" is ok. I just have a 96 OMC fish ski...and I have very little deck room and every little bit will help. Any advice would be greatly appreciated..Thanks

 

[Silvertip]

Re: Replacing 24V trolling motor.. need ground?

Trollers that were capable of operating on EITHER 12 volts OR 24 volts had three wires in the harness going into the motor. Motors that can run on ONLY 12 volts or ONLY 24 volts have only two wires. Sounds like your old motor had three wires (therefore 12/24 volts). That means you need to determine which pair of the three wires was used for 24 volts and YES - one of those must be ground. Your new motor likely is 24 volts only so you need to use the hot wire (24 volts) and the ground wire. At this point however you don't apparently know which one that is. White and Black have both been used as ground wires in the past. With a three wire system however, black may have been the 12 volt source but you don't know that for certain until you determine this. Follow the black and white wires back to the batteries. Ground will be the wire that goes to the negative terminal of the first battery. POSITIVE on that same battery goes to the NEGATIVE terminal of the second battery. Positive on the second battery (+24 volts) goes to the motor. So the long and short of this is yes -- you need +24 volts and ground. That's two wires. You don't need the third wire as it is the 12 volt connection. You just need to determine which wire (white or black) is actually ground. DO NOT GUESS at this. You don't need a meter to determine this.

 

[VaBass328]

Re: Replacing 24V trolling motor.. need ground?

Thanks Silvertip. I really was about to flounder on that one. I knew it was not that easy. It's guys like you that can save idiots like me alot of money. I took your information and compared it to the wiring diagram for the Maxxum 24v 70. All was good until I looked in the boat and I have two "splitters" mounted to the gas tank, where the 12 and 24 go in together. The ground is a a small looped black going to a large black (Ground). Somewhere in the hull the reds must split into red and white; I will just use a voltmeter to find the 24v. Is this right? The great "install" is going down this weekend. I know I am a moron when it comes to this, but times are tough dammit and I got a new trolling motor (Now I have to get through installation-OK mechanics laugh). Any advice (reassurance) would be greatly appreciated. Thanks....

 

[Silvertip]

Re: Replacing 24V trolling motor.. need ground?

I have no idea what the fuel tank has to do with the 24 volt system. What you end up with should look like this. I'm getting the impression that the engine starting battery is used in this system which is not a good idea. You should have two identical deep cycle batteries dedicated to the trolling motor. The engine should be served by a marine starting or dual purpose battery.

The current wiring probably looks like this

 

[VaBass328]

Re: Replacing 24V trolling motor.. need ground?

Thanks Sivertip..I am now 100%..I can't tell you how much I appreciate your help...God Bless!