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Old 04-08-2020, 08:21   #91
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Re: Electrical Fire - Seeking Help Please

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Originally Posted by APWTryfan View Post
Thanks for your reply,

The general concensus here is that there was a problem with the charger. I still have it and will have a closer look later.
No, this was not a problem with the charger. I thought we established that in Post #33, but I'll reiterate.

The pictures show that the black wire was not on the negative terminal of the charger. The nut is still there and there are no burn marks on the negative trace. All the damage is on the first positive post. Both red wires are still connected to the positive posts. They were cut when the charger was removed, and you stated you did not remove the black wire... so where is it? One of the pictures shows it hanging down in the locker to the left of the charger.

The black wire was loose inside the case of the charger. Perhaps it was resting against the negative post and still making a connection while you were at the dock. But then you left the dock and the motion of the boat or vibration of the engine caused the wire to move and come in contact with the first positive terminal causing the short. The charger itself did not short and its internal fuses were not part of the circuit.

Eventually the wires became hot enough to melt the restraints and the black wire fell down out of the picture, breaking the short and probably saving the boat.
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Old 04-08-2020, 08:32   #92
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Re: Electrical Fire - Seeking Help Please

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No, this was not a problem with the charger. I thought we established that in Post #33.

Post #33 is a possible hypothesis, but I have backtracked a bit about the charger not being a cause, since it was a positive that burned up.

Also, I suspect that the trace from that burnt positive post is sufficiently damaged that repair wouldn't be economical.

If the other positive banks of that charger are still working, it could become a nice bench charger, but I would put a new charger onto the boat.
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Old 04-08-2020, 09:10   #93
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Re: Electrical Fire - Seeking Help Please

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Call an electrician, sorry.

We never had a ground from shore charger to the engine. The shore power cord provided its own ground (the three wires).

This is part of the issue with calling a DC negative to the engine (or a DC negative bus bar) a "ground" wire. It technically is not a "ground" but that is commonly referred that way.


You are correct in that the AC shore power should be grounded with a three wire input including a ground. That is grounded to the shore ground. You are supposed to have one and only one ground wire from the AC input to the DC negative main bus (or engine if used for that).
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Old 04-08-2020, 09:18   #94
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Re: Electrical Fire - Seeking Help Please

It's all getting pretty confusing with all the opinions about whether the short was at the charger or not. But one thing is required and that is a short requires a positive to be shorted to a negative. If the red positive wire overheated from a short, somewhere the same current was going through a cable to the DC negative part of the system, either direct to the battery or to a DC negative bus or the engine used as a negative bus. If the cable that the current was going through was bigger than the red positive that overheated, then you might not see the DC negative showing any sign of overheating.


If the DC negative wire that completed the short was the same size or smaller than the red positive that overheated, then the DC negative wire should have also overheated. What could cause an overheating of one wire only is a loose connection creating a localized high resistance and resulting in a lot of heat at that point which could melt the insulation. I wouldn't think that this would melt the insulation along a long cable all the way to the battery or battery switch though.
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Old 04-08-2020, 12:13   #95
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Re: Electrical Fire - Seeking Help Please

Looking at the interior of the charger it appears there is a crack in the reverse polarity protection diode just above the terminals. This could be a secondary reaction to heat or it could be the diode shorted through and created the electrical short. It is one of the few components that actually is connected to both Positive and Negative circuits directly.

Never use metal wiring clips without rubber grommets built in. I prefer to use large tie wraps that use a plastic retainer rather than a metal one.

On you solar panel you are coming directly out of the controller to the battery. There is no reverse flow protection on it. Most likely the panels themselves have a blocking diode built in but the controller most likely does not especially if it is Chinese in origin.
I recommend fusing it and using a battery combiner to isolate it. You loose a tiny bit of current but it protects the solar circuit from damage.

Last of all I keep my boat negatives seperated from the Positive as a matter of course.
If the positive or negative get hot and the insulation fails the likelyhood of a direct explosive short is greatly diminished due to distance. Use firecaulk at bulkhead penetrations to prevent spread of fire.

The charger is toast
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Old 04-08-2020, 12:32   #96
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Re: Electrical Fire - Seeking Help Please

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Originally Posted by Sailorman4009 View Post

On you solar panel you are coming directly out of the controller to the battery. There is no reverse flow protection on it. Most likely the panels themselves have a blocking diode built in but the controller most likely does not especially if it is Chinese in origin.

The charger is toast

Good advice but just to pick up on this point. Most likely most of our solar controllers originate in china it is just that some are re-badged when imported to hide the fact and increase market value. This definitely applies to inverters and probably many other electricals including most computers and phones.
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Old 04-08-2020, 13:30   #97
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Re: Electrical Fire - Seeking Help Please

Super thoughtful LittleWing77 we really appreciate that. Thank you very much we all got teary eyed from your post!

Had our 2nd night on the boat last night and peacefully anchored in Desolation!

Thanks again to all contributors!

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Andy and Family,

Well done!

Your boat is intact, the damage was isolated and your family and your dog are unharmed.

Personally, I have seen an electrical fire overcome (a big, old cabin cruiser) and burn to the waterline in 45 minutes. Ugh. Because of the united quick action of YOUR crew, that did not happen here.

You've received a lot of helpful input regarding what went on with the electrics so you don't need to hear more.

That said, please do take a moment to pat yourself (and all the crew) on the back - as well as your stalwart bucaneers! (Wife and daughter). Right on!

Cool heads and grabbing that fire extinguisher as well as clear-thinking to escape by the forehatch - all excellent responses! It's clear you have an amazing team in the face of unexpected complications.

As traumatic as this was, you all handled it SUPERLATIVELY! Hope this doesn't dissuade any of the crew from sailing and hopefully you will have some sort of celebration for how well everyone mobilized.

Back in the day, apparently the quote at NASA was, "You, Sir, are a steely eyed missile man!"

Now how do we adapt that for your wife and amazing 11-year-old daughter...? Maybe there should be some sort of special, celebratory ritual...!

Warmly,
LittleWing77
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Old 04-08-2020, 15:47   #98
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Re: Electrical Fire - Seeking Help Please

Hey - we ALL need to take a moment to celebrate the-little-things-that-are-really-big-things, don'cha think?

Fair fair winds to you all,
LittleWing77
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Old 04-08-2020, 17:03   #99
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Re: Electrical Fire - Seeking Help Please

Here's a handy reference:


Blue Sea Tables https://www.bluesea.com/support/reference Scroll down to find the PDF download: Protect Your Boat with the Correct Size Wire & Fuse Chart. Handy to keep around.

Battery Fuse Sizing with tables (from Maine Sail)

http://forums.sbo.sailboatowners.com...d.php?t=130775


Also, OLD ProMariners have been reported by our group to be fire hazards. Good idea to toss it. NEW ProMariners are just fine and highly recommended.


OLD https://c34.org/bbs/index.php/topic,....html#msg43151


NEW


Wiring a new charger From Maine Sail:

http://forums.sailboatowners.com/ind...5/#post-880275
and
https://marinehowto.com/installing-a...ttery-charger/
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Old 04-08-2020, 17:32   #100
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Re: Electrical Fire - Seeking Help Please

Thanks Lake Effect; my charger output is 12v at 6 amps. So I should use a 6 amp fuse just before the battery on the positive terminal?
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Old 04-08-2020, 18:07   #101
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Re: Electrical Fire - Seeking Help Please

Keep in mind, on chargers and inverter/chargers, the chassis ground must be the same size as the DC positive cable (one size smaller if the over-current protection will protect it). If the positive wire shorts to the chassis, that ground must be large enough to carry fault current, and clear the fault. In many cases it's the same size as the AC supply wires, and thus much too small.

This is the most common installation error, after absent or incorrect OCP, where chargers and inverters are concerned.

The issue is detailed here https://stevedmarineconsulting.com/i...installations/
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Old 05-08-2020, 02:30   #102
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Re: Electrical Fire - Seeking Help Please

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In a previous life I did two similar insurance boat fire investigation. Both were caused by battery chargers that were connected directly to battery systems. The battery chargers had cicuit protection on the charger end but nothing on the battery end. Shorts occured in the connecting wiring and the 30 amp charger wiring was exposed to hundred of amps flowing back from the batteries.

The normal tunnel thinking is circuit protection at the current source (battery charger). Works fine until a short develops in the wiring an now the source is the batteries. Charging needs to be fused on both ends. Solar and alternators are usually not the same as they are current limited on the normal source end.

One system was factory installed one owner installed.

Frankly

I think you nailed it.



Don't you need to get the electrical system singed of with someone that has 'Authorised Person' status before you get insurance, or a berth at a marina? So a qualified marine electrician?
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Old 05-08-2020, 05:58   #103
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Re: Electrical Fire - Seeking Help Please

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Originally Posted by Steve DAntonio View Post
Keep in mind, on chargers and inverter/chargers, the chassis ground must be the same size as the DC positive cable (one size smaller if the over-current protection will protect it). If the positive wire shorts to the chassis, that ground must be large enough to carry fault current, and clear the fault. In many cases it's the same size as the AC supply wires, and thus much too small.

This is the most common installation error, after absent or incorrect OCP, where chargers and inverters are concerned.

The issue is detailed here https://stevedmarineconsulting.com/i...installations/
Thanks for the link!
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Old 05-08-2020, 07:46   #104
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Re: Electrical Fire - Seeking Help Please

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Thanks Lake Effect; my charger output is 12v at 6 amps. So I should use a 6 amp fuse just before the battery on the positive terminal?
Keep in mind that this additional fuse's job is to protect the wire. What gauge of wire is connecting the charger to the battery? That dictates the fuse size. Here's a link to a table of "ampacity" of marine wire.

Assuming the wire can safely carry 15 A or more, I would use a 10 to 15A fuse up close to the battery. It won't blow under normal charger currents, but if there's a short on the charger wiring, the battery current into the short would quickly blow it.
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Old 05-08-2020, 08:37   #105
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Re: Electrical Fire - Seeking Help Please

Ahoy to any Marina owners reading this. Do you actively audit the safety of the boats you allow in the Marina?

I find it extremely worrying and frightening that someone could have a boat that looks pretty on the outside, but below decks is a fire bomb, and that that fire bomb could quietly berth alongside my boat in the evening when I've gone to bed, or left my boat for the weekend.

Lets assume for a moment that neighbouring boats are shipshape and have had an Authorised Person certify the electrics / gas / engine so are are as safe as you can have a boat in the Marina. If the Fire bomb goes up and takes out two or three more boats in the Marina, who is liable for this?

I would have thought Marina owners would be very pro active in terms of the standards that boats must conform to before they allow them to berth, and certainly for a longer term agreement. But without a formal system, how can a Marina owner protect themselves and boat owners from this?

I guess as a Marina owner, you could have all unknown boats to moor up to buoy that's is a safe distance away from known boats.
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