Electrical Gremlins

[skunther]

I have a DC parallel panel patched onto whatever panel came with my 1993 Hunter Legend 35.5, and it is full of mysteries. Most recently, after replacing my batteries, I wasn’t getting DC power and determined the “house breaker” on the DC parallel panel was no longer working. As we were leaving that day and I couldn’t source a 100amp breaker to replace it, I settled for a 50amp and hoped for the best. Now, when plugged into shore power, the same house breaker trips and won’t stay on for more than a few seconds. I’m not using much amperage - why would it trip when connected to shore power?

I did notice that when I flip it, the voltage to the house battery goes up slightly from 13.2 to 13.3, volt and the starter battery goes up from 12.55 to 13 bolts before the breaker trips. And they settle back to 13.2 and 12.55 respectively. It seems the house parallel panel house breaker is the conduit for the AC charger to charge the starter battery, and the amperage drawn exceeds 50amps?

See image for the “house” breaker referenced.

 

[High Current]

How many amps is your battery charger rated to output? That seems the most likely culprit.

 

[kloudie1]

I dunno, 50 amperes at 120V is 6000 watts which is 500 amps at 12 V way more than a charger would be doing.. The breaker is tripping for some oher reason. Is it a ground fault breaker?? I think you'd see smoke if the breaker is tripping at 50 amperes.. I'd be looking for something that happened during battery hook-up. New breaker could be baad too.. not unheard of. Time to break ouut the multimeter..

 

[Stu Jackson]

I have been around for a long time and have seen all the questions that can be and have been asked. Many of them are very specific, and many of them open Pandora's chest like yours did: essentially the whole can of worms about boat electrical systems. I used to answer them specifically and found myself writing books that ended up going to only one person and a few others who read that thread, and then it disappeared into the internet. I eventually took a different approach and developed this link, Electrical 101. Its introduction explains it all.

Electrical Systems 101 Electrical Systems 101
It's mostly for DC boat systems, but it's unclear what your question actually addresses, seems it's somewhere at the interface of AC and DC, but kloudie's right.

The most important thing you can do, and imho HAVE TO DO is a WIRING DIAGRAM for your boat. It is the ONLY way you can figure out what you have and what any wires and breakers that serve them may be for sure.

Without a wiring diagram none of us can even begin to answer your question 'cuz we'd only be guessing.

Good luck and happy hunting.

 

[skunther]

How many amps is your battery charger rated to output? That seems the most likely culprit.

It's a West Marine WCU-15, rated at 75 amps. The house breaker was formerly a 100amp breaker instead of a 50amp breaker. Maybe the full charge is routed through the house breaker, causing it to trip?

 

[Davidasailor26]

It's a West Marine WCU-15, rated at 75 amps. The house breaker was formerly a 100amp breaker instead of a 50amp breaker. Maybe the full charge is routed through the house breaker, causing it to trip?

Yes, that seems like a good possibility. But +1 to Stu’s advice to trace the wires and make a wiring diagram. Everything will be much more easily understood after that.

I dunno, 50 amperes at 120V is 6000 watts which is 500 amps at 12 V way more than a charger would be doing..

Chargers are generally rated in DC output, and that breaker looks like it’s on the DC panel, so I assume it’s popping from DC current, not AC.

 

[skunther]

I have been around for a long time and have seen all the questions that can be and have been asked. Many of them are very specific, and many of them open Pandora's chest like yours did: essentially the whole can of worms about boat electrical systems. I used to answer them specifically and found myself writing books that ended up going to only one person and a few others who read that thread, and then it disappeared into the internet. I eventually took a different approach and developed this link, Electrical 101. Its introduction explains it all.

Electrical Systems 101 Electrical Systems 101
It's mostly for DC boat systems, but it's unclear what your question actually addresses, seems it's somewhere at the interface of AC and DC, but kloudie's right.

The most important thing you can do, and imho HAVE TO DO is a WIRING DIAGRAM for your boat. It is the ONLY way you can figure out what you have and what any wires and breakers that serve them may be for sure.

Without a wiring diagram none of us can even begin to answer your question 'cuz we'd only be guessing.

Good luck and happy hunting.

Thanks Stu,

A full wiring diagram sounds like a wonderful thing to have. It also seems like a daunting task, and something I am largely ignorant about. I also am a stay at home dad with a 1 year old and 3 year old, struggling to address the obvious tasks I have in front of me to keep this boat functional and safe. Is this a reasonable thing for me to undertake? What do I need, a multimeter with a really long cable to test connections that are up to 35' apart? It sounds very time consuming, but maybe a worthwhile thing?

 

[Davidasailor26]

It sounds very time consuming, but maybe a worthwhile thing?

It can be time consuming, but in my opinion is totally worthwhile. Even if you don’t get every single wire the things you learn in the process will help you greatly in the future. I’d start by reading the electrical parts of Nigel Calder’s Boatowners Mechanical and Electrical Manual. Then get your multimeter and start taking measurements, looking at wire colors, and taking notes.

 

[jviss]

It can be time consuming, but in my opinion is totally worthwhile. Even if you don’t get every single wire the things you learn in the process will help you greatly in the future. I’d start by reading the electrical parts of Nigel Calder’s Boatowners Mechanical and Electrical Manual. Then get your multimeter and start taking measurements, looking at wire colors, and taking notes.

One thing to be careful of is where previous owners have thrown splices in with different color wires. I have a few of these. It's tough to decide whether to just document it, or correct it first! I have cases where they used the wrong color wires to jump things, like red/yellow/green AC wire to extend a DC circuit.

I recently purchased a bunch of Ancor 16AWG primary wire; I have every color now except green with a yellow stripe, tan, light blue, and light green. But, I should be able to straighten out all of my color code issues.

Schematic drawing tools are helpful, but I still haven't settled on one, after decades!

 

[skunther]

It is amazing. I would have assumed there are standard practices for wiring vessels which would make troubleshooting generally easier, in spite of boat owners’ meddling, but it seems every vessel is truly its own beast.

 

[jviss]

It is amazing. I would have assumed there are standard practices for wiring vessels which would make troubleshooting generally easier, in spite of boat owners’ meddling, but it seems every vessel is truly its own beast.

That is the truth! And, note that builders' practices and marine electrical codes have changed over time. There was a time when no one followed any kind of code, that I know of, like into the 1980's. Even then, Catalina still used regular copper stranded with, i.e., not tin plated. Then color codes started evolving, and changing. For example, at some point the "standard" of black for DC negative or ground changed to yellow. And, even so, builders take liberties with color codes since there aren't enough codes to distinguish all the different circuits, and some need more distinguishing, so they use colors!

I have a very frustrating situation where the wires coming down the mast don't match the colors of the ones going to the panel, so there's a "key," or legend I created to map the colors at the terminal block. I'm in the process of making a pigtail with a connector that resolves these colors at the mast base.

Ugh!

 

[Stu Jackson]

A full wiring diagram sounds like a wonderful thing to have.

Sure it would be. But you don't have to do a FULL COMPLETE one. You only have to do one that includes the breaker you have been popping. Find out what it connects to, at each end, and build from there. Ya don't eat an elephant in one sitting, you do it a bite at a time. All the time you'd spend guessing and hoping would be better spent tracing a few wires, for starters. Heck, you might find something obvious. You want a SAFE boat, you said. Go spend the quality time to do so.

 

[capta]

Welcome to marine electrickery. No, it isn't misspelled.