Common Ground

[kball]

Hey guys,<br />I just got my trolling motor for my new pontoon. I was flipping through the manual for installation instructions, and saw a small section about establishing a common ground. I am planning on using the Trolling motor batteries (this is a 24v system) for the trolling motor only and physically isolating them completely. All other accessories (radio and depth finder) will be run off the main battery. Do I need to establish this common ground? And if I do, what does this mean and how do I do it?. I am planning on installing the trolling batteries under one of the front bench seats. The main battery is in the back of the boat. THe manual is rather vague regarding this issue. <br /><br />Thanks<br /><br />Mac

 

[Silvertip]

Re: Common Ground

There is no need to provide a common ground with the other electrics on your vessel. Connect the batteries in series to deliver 24 volts and connect your troller. Head out fishing.

 

[kball]

Re: Common Ground

That's what I figgerd. The reason in the manual was to prevent gavanic corrosion. Can you maybe enlighten me as to when I would need to do this and why. I'm just trying to gather information, now. Thanks so much, YOU GUYS ROCK<br /><br />m

 

[Dunaruna]

Re: Common Ground

Originally posted by Upinsmoke:<br /> There is no need to provide a common ground with the other electrics on your vessel.

Not 100% correct. Depends on other factors such as what type of material the toons are made of.<br /><br />Aldo

 

[kball]

Re: Common Ground

THey're Aluminum, could you elaborate?

 

[Dunaruna]

Re: Common Ground

Galvanic corrosion occurs because an electric current flows between two different metals. Earth (ground)leakage is part of that process, that's why shore power leakage causes so much trouble (it's actually not galvanic corrosion but the damage is similar). The least noble of metals suffer the most. Aluminium is low on the scale of nobility.<br /><br />Now to your kicker, it's basically a starter motor underwater. What are the chances in a few years time that it developes a ground leak. Bonding all the underwater metals will minimise the damage.<br /><br />I suspect that the manufacturer of your motor is trying to cover all bases by recommending common ground straps but you need to contact them and get more detailed instructions - it's a complicated subject.<br /><br />Aldo

 

[Silvertip]

Re: Common Ground

While I agree -- this application is in Iowa and obviously a fresh water boat. If galvanic action were a problem, there would be no floatable boats in the midwest. There are thousands of boats (old and new) in the midwest and if one mentioned galvanic action and common ground you would very likely get the "deer in the headlights look". And that would be from the marine tech. It is certainly a consideration on large boats with complex electrical systems but I've not seen it as a problem on smaller boats.

 

[jtexas]

Re: Common Ground

aldo, here in the northern hemisphere, it's the water that leaks. We rarely, if ever, have a problem with leaking ground. <br /><br />sorry, just couldn't resist.

 

[kball]

Re: Common Ground

So.. in conclusion.. It would be a good idea, but probably isn't crucial. If I wanted to do this, would it just involve running a wire between the negative post on the Trolling battery to the negative post on the starting battery? THanks for all your help. <br /><br />m

 

[eurolarva]

Re: Common Ground

If you are using one trolling motor for one set of batteries your common ground is the black wire going to the minus terminal. Because this is the only equipment you are running on this or these batteries you dont need to worry about the term common ground. If you had 5 different items running on your batteries your common ground would be the minus terminal for all your equipment. Do not worry about running a grounding strap to the metal on the boat or to your other battery. Just remember if you are only running the trolling motor and because it is not connected to the charging system on your motor you will have to recharge the battery after every use.