24volt trolling motor question about wiring

[SportShot]

After purchasing a used boat I had it out on the water and everything seemed to work properly. The trolling motor is a 71lb thrust Motor Guide, 24volt. I decided to remove the deep cycle batteries and charge them up. When I opened the battery box the two batteries did not appear to be wired in series. There were four wires running into the box...

1 solid black
1 solid red
1 striped black
1 striped red

The solid wires were attached to one battery and the striped wires were attached to the other battery. More confusing is that they were both wired black to positive and red to negative, yet the trolling motor turned in the correct direction

How is this possible considering it is DC? I had always thought that for 24volt the batteries had to be wired in series with a jumper wire from the positive of one to the negative of the other. Did the previous owner have the batteries wired wrong or is there something I'm missing? I would be thankful for any help.

 

[glenn property of pam]

Re: 24volt trolling motor question about wiring

do you have either a 4 pin trolling plug or a selector switch for 12/24v on the front of the boat (not the trolling motor)

 

[SportShot]

Re: 24volt trolling motor question about wiring

do you have either a 4 pin trolling plug or a selector switch for 12/24v on the front of the boat (not the trolling motor)

The plug is 4 pin. I used a meter and all I get off the pins is 12volts. The front panel has, in addition to the plug, an on/off switch which I have not been able to determine its purpose, and a tilt/trim switch.

 

[glenn property of pam]

Re: 24volt trolling motor question about wiring

there is a jumper inside the male plug on the trolling motor that does the connection for 24v. Its a nice set up especially as the leads are marked correctly

the on/off could be a light, live well or bilge pump manual switch

 

[SportShot]

Re: 24volt trolling motor question about wiring

Wow, I have never heard of it being jumped inside the plug itself. Thanks. What is still mysterious is why the batteries are wired red to neg and black to pos and how the motor still turns in the correct direction. I wonder if I should try switching them to see what happens.

 

[Barnacle_Bill]

Re: 24volt trolling motor question about wiring

What make/model is the TM?

 

[SportShot]

Re: 24volt trolling motor question about wiring

What make/model is the TM?

Motor Guide, 71lb thrust, 24volt

I believe the motor was a package deal on the boat when it was new. The boat is a 2000 Fisher Spectrum 18.5

 

[glenn property of pam]

Re: 24volt trolling motor question about wiring

if its wired wrong you have to be real careful about changing anything. Firstly open up the plug as this may be a case of wired wrong one end then someone rewired the other end to suit. If you change one battery you can cause a short.

check all ends and connections and draw it out before undoing anything. Only when you understand how its working at this point in time can you then decide how it should be wired

 

[SportShot]

Re: 24volt trolling motor question about wiring

if its wired wrong you have to be real careful about changing anything. Firstly open up the plug as this may be a case of wired wrong one end then someone rewired the other end to suit. If you change one battery you can cause a short.

check all ends and connections and draw it out before undoing anything. Only when you understand how its working at this point in time can you then decide how it should be wired

On second thought, I'll leave well enough alone. It works properly and I guess that is all that matters. When I eventually replace the carpet I can check the wiring for any modifications the previous owner may have made.

 

[glenn property of pam]

Re: 24volt trolling motor question about wiring

I would have to check just to make sure that it is connected to 24v. The idea of the 4 pin plug is you can wire it in the plug to be 12v dual or 24v single. The trolling motor would run on 12v but it would be slow. If you are uncomfortable with wiring and the trolling motor seems to be powerful (running on 24v) then leaving it is a option for now.

 

[Barnacle_Bill]

Re: 24volt trolling motor question about wiring

What is the model number? Is there a 12/24 switch on the TM?

 

[SportShot]

Re: 24volt trolling motor question about wiring

I'm not sure what the model number is but I will find out. I keep the boat in storage a few miles away.

 

[SportShot]

Re: 24volt trolling motor question about wiring

After charging both of the batteries and then using the trolling motor for two days, I checked the voltage on them. One of them read 8.4volts. The other read 12.6volts. So...one of them isn't being used at all although it is hooked up. This means that it's not converting to 24volts inside the plug.

Now I will try to wire the batteries in series using the wires that were connected to the battery that drained. What the other two wires are for I still have no idea.

 

[glenn property of pam]

Re: 24volt trolling motor question about wiring



this is what most 4 pin, 4 lead boats use for trolling. If you only have 2 wires to the trolling motor you can wire this way. All connections are made in the trolling plug not on the boat. (notice 2 breakers is preferred)

 

[SportShot]

Re: 24volt trolling motor question about wiring



I just found this while searching for motorguide 4-pin wiring diagrams. I think it's basically the same. I will take the front panel off the bow and double check the wiring there to make certain the previous owner hasn't changed it.

 

[Silvertip]

Re: 24volt trolling motor question about wiring

Try things you don't fully understand and you may end up with smoke and fire. You were asked if your motor had a 12/24 selector switch. That meant "on the motor" not on the panel. We already know the panel doesn't have one. If your motor has only two wires between it and the plug then you have a 24 volt ONLY motor. It is not configured for 12 volt operation. While you may know that, you never confirmed it. So ---- Forget the diagram you just found because it is incorrect for your application (and most others as well).

Here is what a 24 volt only system looks like. (We will get to the four wire stuff in a minute.)



Since you have a 24 volt only motor, unless the plug on the motor cable has the jumper and it is properly wired, you will never get 24 volts from the four wire system. So your options are, use the correct plug and forget about rewiring the batteries as they are intended to be in that configuration. If all of this confuses you, then study the above diagram carefully. What you can do is eliminate two of the four wires since they are wasteful due to the length and voltage drop. The remaining two will provide a 24 volt only system. Inspect the plug on the motor cable to ensure it does or does not have a jumper on it. If it does, remove it and note which two pins the red and black motor leads go to. The mating two terminals in the 4-contact receptacle will have 24 volts on them when we are done. Remove the panel to see what the wire colors are on the two terminals we just discussed. Those two wires will be the ones we use from the batteries. On the battery on the left, disconnect the wire on the POSITIVE terminal and tape it off. DO NOT CUT IT FROM THE SYSTEM. On the battery on the right, disconnect the wire on the NEGATIVE terminal and tape it off. Again, DO NOT CUT IF FROM THE SYSTEM. Install a jumper between the POSITIVE terminal on the left battery and NEG terminal of the right battery. Be certain the two wires you saw at the receptacle are the same two you USE at the batteries and that polarity is observed. NEG at the battery must match with NEG (black) on the motor. Plug in the motor and go boating.

 

[SportShot]

Re: 24volt trolling motor question about wiring

Thanks,

The reseptacal has four pins. The motor plug has 3 wires, 2red and 1black. The plug cannot be taken apart but I would imagine that the 1black wire connects to two of the pins for ground. It does not appear to have a jumper inside.

I worked on it yesterday. I basically figured that I only have two batteries so there is no way I can produce more than 24 volts and fry the motor. I ended up using only two of the four wires just like you say. I am now reading 24volts at the receptacal. I plugged the motor in and it turned backwards. I had to revert to red to neg and black to pos to get the motor turning the right direction. The wiring must have been altered at some point in time. Since I am now reading 24volts at the receptacal and the motor is turning correctly I think I got the problem licked. The batteries are wired in series like the diagram you shared. Thanks again