Getting Current Through Hull

[jiffer]

Using a voltmeter I touch the negative lead to the hull of the boat and then touch the positive lead the positive of my cranking batter, it shows there is 12+ volts of current.

Is this bad?

I disconnected everything except the main engine and no change. I disonnect the main engine and reconnect all the other leads, I don't get current.

With all the wiring in these boats, where do I even begin looking for this if it's not supposed to be that way?

[yarcraft91]

Aluminum hull, right? With the main motor connected to the battery, you see 12V difference between the battery + terminal and the boat hull? You should also see 0V difference between the battery - terminal and the hull. That's because the battery - terminal is connected to the block of your main motor, which is electrically connected to the motor mounting bolts, which are electrically connected to the hull. What you see is normal because the motor and hull are grounded to your battery - terminal.

[jiffer]

Yes it's an aluminum hull. So that normal? Cool.

I'm trying to figure out why my bow mount motor goes crazy when I have it on and start the main engine.

You think that could be caused by my onboard charger picking up the current and sending it to the bow mount?

Motorguide said that it's not their motors fault.

[boat nut]

Yes it's an aluminum hull. So that normal? Cool.

I'm trying to figure out why my bow mount motor goes crazy when I have it on and start the main engine.

Are you using your cranking battery to run your trolling motor?

[jiffer]

No. I've got the cranking batter that runs the main engine, kicker, and bow electronics.

The bow mount is 24v Motorguide PTSv that also powers the pinpoint 7420. The power for the 7420 is supposed to come off the bow mount as it has one cable that connects.

[perchjerker]

Yes it's an aluminum hull. So that normal? Cool.

I'm trying to figure out why my bow mount motor goes crazy when I have it on and start the main engine.

You think that could be caused by my onboard charger picking up the current and sending it to the bow mount?

Motorguide said that it's not their motors fault.

no the charger is not picking up current. Current is not flowing in your hull. Voltage and current are 2 different things.

your problem lies elsewhere

I would check all your trolling motor connections and fuse holders etc

[REW]

You use a term:
"My bow mount goes crazy, when I start the big motor."

What do you mean by this statmenet?
Is the motor changing direction, is the motor changing speed, or is the motor not doing anything out of the ordinary, but your bow mounted depth finder is doing something out of the ordinary?

It would be very unusual to have any action on the part of the big motor to cause an issue with a trolling motor.

It is fairly common, where the big motor might cause an issue with a depth finder. If you do have such an issue, the first thing to look at is the spark plugs and wires on the big motor. If you are getting interferecne on the depth finder, the first thing to do is to make sure that you are running resistor style spark plugs on your motor. Resistor style spark plugs go a long way to eliminate spark caused interference generation by the big motor.

Take care
REW

[jiffer]

The "trolling motor goes crazy" means that it changes direction irradically and changing speed and throttling up and down. I meand C R A Z Y!

I get no interference on the fishfinder though (either one). No other electrical problems.

For what it's worth, here's a description of my rig/setup.

1998 Starcraft Superfisherman
1998 Mercury 115 ELPTO (2+2)
2002 Yamaha T8 (electric start/tilt trim/tiller with trollmaster)
Cannon Electric Downrigger
2008 Motorguide PTSv 82 lb thrust 24v
2001 Pinpoint 7420 (bow)
2001 Lowrance X-85 (console)
Guest charger (2x10amp)

The trolling motor is wired with the factory wiring. I have the guest charger hooked up to the two batteries. I have four wires coming from the batteries to the female plug, then the plug to the motor has 3 wires but I only use two.

Before this bow mount I had a motorguide Excel that did the same thing.

I have no wires shorting out or any other electrical problems. THe dash has breakers so I don't have a fuse box. No weird battery drains and everything works fine except for this one problem. Diode's show no unusual corrosion on them either.

I'm not afraid to start swapping out parts but not sure where to start.

[Hot Runr Guy]

Maybe I'm off base here, but I'm just not a big fan of the 4-wires from battery to plug setup, and the need for jumpers and such in the plugs. I'd clean up the TM wiring, running just (2) 6-gauge wires from the series-connected batteries to a good TM plug combination. You mentioned that this happened with your previous TM too, so let's start looking at something the rigging has in common between them.
HRG

[jiffer]

Thanks Hot one. I'll get that all cleaned up and see what it does.

[jiffer]

Will I have to disconnect the jumper cable between the two batteries to charge it with the onboard charger?

[Hot Runr Guy]

Will I have to disconnect the jumper cable between the two batteries to charge it with the onboard charger?
No. It appears as though you have a 2-bank (2x10amp) charger, so the jumper stays in place. 1 pair of charger leads should be attached to the pos & neg of one battery, the other set of charger leads should be attached to the pos & neg of the other one. The jumper should run from the positive terminal of one battery, to the negative of the other. The leads that run to the TM plug should then come from the remaining pos and neg terminals, which will give you the 24volts you need for the TM.
HRG

[RDJ]

"The trolling motor is wired with the factory wiring. I have the guest charger hooked up to the two batteries. I have four wires coming from the batteries to the female plug, then the plug to the motor has 3 wires but I only use two."

I am confused by this description of 24V wiring. Do you mean you have 2 leads (neg post & Pos post) going from each battery (total of 4 wires, 2 neg/2 pos) going to your outlet for your bow mount AND also have the traditional jumper wire (neg or pos post of bat#1 to opposite of bat#2) to make 24V system? I guess I have never seen this and don't understand the rational behind it.
If your cranking battery or main motor isn't in any way electrically connected to your trolling motor batteries and your bow mount electrical system is isolated from the rest of your boats electrical systems, I don't see how the two seperate systems could affect one another. I would think the only way they could possibly have any affect on one another would be to both be in the same electrical circuit and have one device putting a draw on the other when starting up or under load?

[jiffer]

No, I don't have the jumper on it now. I will when I just have two leads going to the new plugs I ordered.

The 24volt conversion is made in the plug currently with two leads coming off of each of the 2 batteries.

Your confusion as to how this all can happen when they are completely electrical problems is exactly why I'm confused too.

Based on Hot Runners advice I'm going to put brand new wiring and plug for the trolling motor as maybe that is where interference somehow is getting through from the aluminum hull or the other boat wiring such as livewells, lights, tilt/trim etc.

[Hot Runr Guy]

"I will when I just have two leads going to the new plugs I ordered."

Jiffer, I'm curious, what new plugs did you order?" There aren't a lot of styles that will fit 6 gauge wire, if you chose to go that route.
HRG

[jiffer]

I went with the ConnectPro from Cabelas as it is the only one I can find that will take 6 gauge. The interesting thing is that the wire on the motor going to the plug is only 8 gauge.

http://www.cabelas.com/cabelas/en/templates/pod/standard-pod-wrapped.jsp?_DARGS=/cabelas/en/common/catalog/pod-link.jsp_A&_DAV=MainCatcat21276-cat21380&rid=&indexId=cat21380&navAction=push&masterpathid=&navCount=1&parentType=index&parentId=cat21380&id=0000967

Universal ConnectPro™ Trolling Motor plugs and receptacles fit all 2- or 3-wire configurations. Locking plug eliminates loose connections. Works with 12-, 24-, 12-/24-, 24-/36- or 36-volt systems. Watertight sealing cap protects the receptacle when not in use. Accepts up to 8-gauge wire.

with this

The 6-Gauge Adapter lets you use the ConnectPro™ Plug and Receptacle with 24- or 36-volt systems that use heavier 6-gauge wire.

[Hot Runr Guy]

Cabelas also carries this one: http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=MainCatcat21276-cat21380-cat21380&id=0001305010748a&navCount=3&podId=0001305&parentId=cat21380&masterpathid=&navAction=push&catalogCode=IJ&rid=&parentType=index&indexId=cat21380&hasJS=true

but they are pricey. Of course, you could probably get the same plugs and sockets at Home Depot for half the cost, without the Marinco name on it.

they also carry this style, like are used on fork lifts and similiar industrial equipment:
http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=MainCatcat21276-cat21380-cat21380-cat21380&id=0001110011811a&navCount=5&podId=0001110&parentId=cat21380&masterpathid=&navAction=push&catalogCode=IJ&rid=&parentType=index&indexId=cat21380&hasJS=true

Let us know if this cures your electrical demon. Of course, if you choose to register here on WC, you get to learn the secret handshake.:howdy:
HRG

[boat nut]

No. I've got the cranking batter that runs the main engine, kicker, and bow electronics.

The bow mount is 24v Motorguide PTSv that also powers the pinpoint 7420. The power for the 7420 is supposed to come off the bow mount as it has one cable that connects.

Is it possible that you have two power sources connected to your bow sonar? That's what this previous post appears to say. If that is the case, disconnect one of the two sources. It is also possible (I'm not familiar with motorguide/pinpoint installs) that you have power from the cranking battery and only a sonar puck connection from the motorguide TM. If you do have two power sources connected to this device, or, if the device connected to the TM batteries is networked with a device powered from the cranking battery, it would explain everything.

[jiffer]

Whoops. I meant to say "console electronics" instead of "bow electronics" in this statement: No. I've got the cranking battery that runs the main engine, kicker, and bow electronics.

[RDJ]

Gotcha Jiffer, I was putting your "remove the jumper" post in relation to your current wiring scheme, not your future wiring scheme. thanks and good luck..

RJ in Montana

[yarcraft91]

This connector has worked well for me for the past 3 seasons. Handles 6 ga wire and that's what I'm using.

http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=MainCatcat21276-cat21380&id=0001110011811a&navCount=4&podId=0001110&parentId=cat21380&masterpathid=&navAction=push&catalogCode=IJ&rid=&parentType=index&indexId=cat21380&hasJS=true

[jiffer]

The marinco was more, but I'm paying more hoping that I can keep the front control panel in as near a factory condition as possible. I'm not very handy, so if I had to cut a new opening for the female end it probably wouldn't look very good.

Thanks guys. I'll let you know if this solves my problem.

[clumpner@yahoo.com]

By reading the problem your having I would look back to the trolling motor itself. By any chance did this behavior begin after the trolling motor was in the rain? This motor has a known problem of the head leaking, causing the circuit board in the head to short out and the motor to exibit the problems you described.

The one I had would do different things at different times, like turning back and forth rapidly, change speeds, the LED display going out and others. In each of the 5 times I had mine in for repairs, they had to swap out the main board. I finally had it with Motorguide and got rid of it after no support from Motorguide.

Hope your's turns out to be something else, but you may want to contact John @ Anchors Aweigh in Waukesha. He was the guy who worked on mine and he reall knows the motor.

[jiffer]

Clumpner,

This motor is brand new. Has not been in rain. All electronics on these digital versions are in the lower unit now. I replaced my Excel that I had for 7 years cuz it finally went bonkers.

I went with motorguide 7 years ago because I had a Minnkota that went to Minnkota 6 times in 3 years and never ever worked right and I felt I had no support from Minnkota. LOL

Motorguide has offered to have me send it in for repair and will pay for all shipping. Minnkota never ever offered that even when I'd unpack the motor after receiving it back from them, no change in operation and immediately called them and said nothing changed.

[Jiffer]

I upgraded the wiring, breaker, and plug. No change in this problem. I even disconnected the onboard battery charger and that didn't fix the problem either.

Could this be interference from plug wires or alternator on the Mercury? It does not do this when I run my electric start T8 kicker.

[Hot Runr Guy]

It took a bit of research, but the standard NGK plugs are not considered "suppression" spark plugs. Here is a link from NGK's site regarding electrical noise, plus a link showing the suppression part numbers, which in your case would be a BPZ8H-N-10 (the standard plug being a BP8H-N-10. Might be worth a try.
HRG
http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqresistor.asp?mode=nml

http://outboardmarine.com/spark_plugs_twostroke.html

[boat nut]

I'm thinking like HRG, but first, is your trolling motor equipped with a co-pilot? If so, have you unplugged it to see if that stops it?

[jiffer]

I'm thinking like HRG, but first, is your trolling motor equipped with a co-pilot? If so, have you unplugged it to see if that stops it?

Yes it has the co-pilot and it has no effect. I can also unplug the fishfinder and the foot pedal and it has nothing to do with it.

I went to Checker and asked for that plug. They gave me the standard. So I'll go pack and get the suppression one. Should be able to try it out next week if I get it in time.

[jiffer]

Well, the new plugs worked! I can actually use the bow mount now when the main engine is running. So no more shutting down the fish finder and unplugging the motor when researching for that spot on the spot or just scooting down to the next point.

Thanks!!!!!!!

[Hot Runr Guy]

Well, the new plugs worked! I can actually use the bow mount now when the main engine is running. So no more shutting down the fish finder and unplugging the motor when researching for that spot on the spot or just scooting down to the next point.

Thanks!!!!!!!
Jiffer,
Glad to hear we figured out a solution. Once you register on WC, we'll let you know where to send the Cabelas gift cards!
HRG