Frigoboat compressors rusting and lines corroding.

[cardude]

I just noticed that my Frigoboat system is corroding really badly. It looks really bad! I guess I have t looked at them in awhile. [emoji35]
I moved the boat to another marina last year. Could depleted zincs on the keel cooler cause this?



There is a bonding wire hooked to the keel coolers it appears but not to the compressors. Should the compressors be hooked to the bonding system?

[Kenomac]

I’ve noticed the same thing happening on a couple of newly installed units. Not sure why it’s happening on some and not others. The cabinet where they’re located is well-ventilated.

One unit began to have surface rust prior to installation.

[cardude]

So that doesn’t appear to be galvanic corrosion to you? I need to test for stray current at this marina. It’s a pretty old, crappy marina.

I think I have a silver cell lying around here somewhere.

Just looking around more, I’m noticing some corrosion on the fairly new Balmar charge controller I installed last year. Should that be corroding so soon? I’m a little electrically challenged and freaking out a little here.

[Richard Kollmann]

Originally Posted by cardude

I just noticed that my Frigoboat system is corroding really badly. It looks really bad! I guess I have t looked at them in awhile. [emoji35]
I moved the boat to another marina last year. Could depleted zincs on the keel cooler cause this?

Attachment 171401Attachment 171402

There is a bonding wire hooked to the keel coolers it appears but not to the compressors. Should the compressors be hooked to the bonding system?
Attachment 171403

The Danfoss BD compressors do discharge a very small amount of low voltage current into seawater if it can find its way there. The oxidation in picture is most likely from water dripping from above compressor. Clean up compressor and line and paint with rust preventing paint. I believe Frigoboat recommends running a wire from the connection on keel cooler to battery ground and not to a through hull. You do not want the cooler to serve as a sacrificial ground for the boat. Best check with Frigoboat USA.

[cardude]

I’m scheduled for a haul out tomorrow morning so I can check all the zincs and just do a basic inspection, and in the between time I started doing some testing with my silver cell and multimeter. I put the electrode for the cell to the negative on my multimeter and tested some things with the positive electrode. Here are the DC voltage readings to some things I tested.

Bonding system -232mv
Copper wires running from the compressors to the keel cooler -232mv
Seacocks -232mv
A transducer for my Garmin system -125mv [emoji15]. Why would this read so much higher?

According to this table, the readings should be in these ranges. I’m not familiar with galvanic corrosion or much concerning electrical so maybe I’m thinking about this wrong, but if it’s less negative (higher reading) don’t I have a problem? Also, how do I measure if there is a stray current at my marina? There are some pretty crappy steel hull boats a few slips away from me so I wonder about that. How do I test for that?

[Richard Kollmann]

Originally Posted by cardude

I’m scheduled for a haul out tomorrow morning so I can check all the zincs and just do a basic inspection, and in the between time I started doing some testing with my silver cell and multimeter. I put the electrode for the cell to the negative on my multimeter and tested some things with the positive electrode. Here are the DC voltage readings to some things I tested.

Bonding system -232mv
Copper wires running from the compressors to the keel cooler -232mv
Seacocks -232mv
A transducer for my Garmin system -125mv [emoji15]. Why would this read so much higher?

Rust on compressor has nothing to do with stray current discharge into seawater.

According to this table, the readings should be in these ranges. I’m not familiar with galvanic corrosion or much concerning electrical so maybe I’m thinking about this wrong, but if it’s less negative (higher reading) don’t I have a problem? Also, how do I measure if there is a stray current at my marina? There are some pretty crappy steel hull boats a few slips away from me so I wonder about that. How do I test for that?

Attachment 171482
Attachment 171483

I am sorry I do not know much more about stray voltage except keeping Zincs fresh and do not discharge this compressors low voltage into fresh water metal tank especially on an aluminum boat.
Frigoboat has confused us with first not using zincs, then installing two in in keel cooler, and now saying zincs are not required. I have pictures of cooler zincs Eaton away and one with most of the cooler bronze missing. This is why I do not think it is a good to use keel cooler to dispose of all boats low voltage.

[Anna Sail]

You are confusing different types of corrosion with simple rusting. If you look at your fittings and lines, you will see evidence of salt water ingress. Best to focus on making the location of the compressors water tight. Bear in mind, the controller mounted on the compressor is an electrical device; a splash of water will kill it. I suspect you've been very lucky.

Regarding Richard's comments on Frigoboat "confusing us", allow me to defend them: Keel Coolers are available with or without sacrificial zincs. It is a requirement of the installation that an electrical connection is made between the Keel Cooler and the battery negative. In satisfying this requirement, the Keel Cooler is often connected electrically to the boat's sacrificial zinc that is protecting the other underwater metal fittings. If this is found to be the case, a Keel Cooler with zincs is not necessary. If your boat does not have a bonding system or employs non-metallic underwater fittings it would be advisable to use a Keel Cooler with zincs as a safety precaution.

[cardude]

Originally Posted by Anna Sail

You are confusing different types of corrosion with simple rusting. If you look at your fittings and lines, you will see evidence of salt water ingress. Best to focus on making the location of the compressors water tight. Bear in mind, the controller mounted on the compressor is an electrical device; a splash of water will kill it. I suspect you've been very lucky.



Regarding Richard's comments on Frigoboat "confusing us", allow me to defend them: Keel Coolers are available with or without sacrificial zincs. It is a requirement of the installation that an electrical connection is made between the Keel Cooler and the battery negative. In satisfying this requirement, the Keel Cooler is often connected electrically to the boat's sacrificial zinc that is protecting the other underwater metal fittings. If this is found to be the case, a Keel Cooler with zincs is not necessary. If your boat does not have a bonding system or employs non-metallic underwater fittings it would be advisable to use a Keel Cooler with zincs as a safety precaution.

I guess what is confusing me is the refrigerator system is all in its enclosed area that also includes the generator, the battery bank, battery charger, and some other electrical systems. I don’t see any evidence of a salt water leak anywhere, or a rainwater leak, but I will check that again. That’s why I was thinking it might be galvanic corrosion. But you are right— I don’t know much about electrical systems and what causes different kinds of corrosion.

I did have a raw water pump on the generator dripping last year that took me awhile to catch. Maybe it’s possible that seawater atomized somehow and saturated the air in this area? This area is not sealed from the exterior of the boat either because the generator has to get air, so maybe it is just regular old rust that I didn’t catch. That’s embarrassing

[OzePete]

Originally Posted by cardude

I just noticed that my Frigoboat system is corroding really badly. It looks really bad! I guess I have t looked at them in awhile. [emoji35]
I moved the boat to another marina last year. Could depleted zincs on the keel cooler cause this?

Attachment 171401Attachment 171402

There is a bonding wire hooked to the keel coolers it appears but not to the compressors. Should the compressors be hooked to the bonding system?
Attachment 171403

In the meantime spray with WD40.
Cheers Ozepete

[Richard Kollmann]

Originally Posted by cardude

I guess what is confusing me is the refrigerator system is all in its enclosed area that also includes the generator, the battery bank, battery charger, and some other electrical systems. I don’t see any evidence of a salt water leak anywhere, or a rainwater leak, but I will check that again. That’s why I was thinking it might be galvanic corrosion. But you are right— I don’t know much about electrical systems and what causes different kinds of corrosion.

I did have a raw water pump on the generator dripping last year that took me awhile to catch. Maybe it’s possible that seawater atomized somehow and saturated the air in this area? This area is not sealed from the exterior of the boat either because the generator has to get air, so maybe it is just regular old rust that I didn’t catch. That’s embarrassing

It looks to me in the picture that moisture has also reached the Merlin board terminals. At some point the Merlin will short out.

I would cut a piece of cardboard and temperately fasten it high above compressor and run the various equipment to look for moisture do not forget rain water or prop shaft seal.

Once again this moisture damage has nothing to do with vow voltage discharge.

[OzePete]

Spray all metal with WD40. Including wiring, connectors, electrical and piping.

[Richard Kollmann]

Originally Posted by OzePete

Spray all metal with WD40. Including wiring, connectors, electrical and piping.

cardude, I would clean up the mess first after finding where moisture is coming from before making a mess with WD40. I would also remove and clean the Merlin with contact lude cleaner.

[cardude]

Is the Merlin under the black box?

[Richard Kollmann]

Originally Posted by cardude

Is the Merlin under the black box?

Frigoboat gave me a merlin one speed controller but I have not seen the merlin ll.

What I called the merlin is the small circuit board plugged into top power pins of Danfoss module. Does this unit run on AC/DC ? This boards mail and female connections both maybe corroded so be sure to label wires before removing and cleaning them.

[a64pilot]

WD40 doesn’t hurt anything I guess, but I have had much better luck with Corrosion-X. I got my experience with it on magnesium aircraft gearboxes exposed to salt spray, magnesium corrodes just by looking at it.
I think Pete’s point was do something, but do it quickly.

I think I would wire brush off the rust leaving a light coating, then apply rust converter, let it dry and brush paint.
Then coat every thing with Corrosion -X, just be sure your done painting before you apply the Corrosion- X.
Methinks you just have rust from condensation or a leak, salty air maybe, not electrical in nature.