24v trolling motor electrolysis

[Mferg318]

I recently bought a new boat and noticed some electrolysis on the minn kota trolling motor. The trolling motor is the only think wired to the trolling motor batteries. Everything else is wired to the 12v cranking battery. I’ve been finding some conflicting information online. Do I need to have a common ground between the trolling motor system and the cranking battery? Or should they stay isolated? Not sure if it matters, but all 3 batteries are wired to a Bass Pro Shops 3 bank charger. Thanks for your help

 

[dingbat]

I recently bought a new boat and noticed some electrolysis on the minn kota trolling motor. The trolling motor is the only think wired to the trolling motor batteries. Everything else is wired to the 12v cranking battery. I’ve been finding some conflicting information online. Do I need to have a common ground between the trolling motor system and the cranking battery? Or should they stay isolated?

Everything wired to common ground potential.

Could be any of a number of issues.
Boat kept in water?
shore power in play?
Saltwater?

 

[Mferg318]

Boat never stored in water, so no shore power either. 2 things I can think of. When I got the boat he had the trolling motor wired incorrectly so that only 12v was getting to the plug up front. Also, the horn was broken off at the bow but still has some wiring attached. Maybe that was touching the hull and causing some issue? No idea if any of that matters, just throwing some stuff out there.

 

[dingbat]

Boat never stored in water, so no shore power either. 2 things I can think of. When I got the boat he had the trolling motor wired incorrectly so that only 12v was getting to the plug up front. Also, the horn was broken off at the bow but still has some wiring attached. Maybe that was touching the hull and causing some issue? No idea if any of that matters, just throwing some stuff out there.

Three things that cause it… stray current, dissimilar metals in contact with each other and improper grounding.

Trolling motors not specifically designed for saltwater use don’t last long if used in salt

 

[Mferg318]

Three things that cause it… stray current, dissimilar metals in contact with each other and improper grounding.

Trolling motors not specifically designed for saltwater use don’t last long if used in salt

Before buying I asked the previous owner if he used it in saltwater and he said no, but after going through it in detail I saw some signs that pointed to saltwater. Would saltwater corrosion cause the white powdery stuff that makes the paint bubble and flame off? Maybe it’s just saltwater damage and not electrolysis.

 

[dingbat]

Would saltwater corrosion cause the white powdery stuff that makes the paint bubble and flame off?

White powder (Aluminum hydroxide) and lifting paint is aluminum corrosion. A condition where moisture gets trapped on the surface of the aluminum. In this case water got trapped between the aluminum and paint.

The process could have been initiated by galvanic corrosion (blistering painted) but something as simple as a chip in the paint can start the process.

 

[Mferg318]

White powder (Aluminum hydroxide) and lifting paint is aluminum corrosion. A condition where moisture gets trapped on the surface of the aluminum. In this case water got trapped between the aluminum and paint.

The process could have been initiated by galvanic corrosion (blistering painted) but something as simple as a chip in the paint can start the process.

Thank you for this explanation. I’ll complete my due diligence in checking the electrical to rule out electrolysis, but it might just be good old saltwater damage.

 

[dingbat]

Thank you for this explanation. I’ll complete my due diligence in checking the electrical to rule out electrolysis, but it might just be good old saltwater damage.

Saltwater is a facilitator, not a Process.
The same Process can happen in freshwater as well... it just takes longer