Mystery electrical system problem - not sure how to proceed.

[Sunbeam]

Hi folks,

I have a mystery (to me anyway) electrical problem. My maine fuse has blown twice within the past two weeks. Without it, I have engines and bilge pumps, but no instruments, helm stuff, lights, etc. What scares me about it is that it's not in my area of expertise, and it's seemingly random (so I don't even begin to know how I would have a pro find/fix it; and anyway I would rather understand it and figure it out myself, just for the knowledge). I'd really appreciate your help or ideas.

So, beginning of the problem:

A week or so ago (after three weeks of full time cruising/living aboard without any electrical problem), my main, 30-amp fuse blew. At the time the trim tabs were auto-retracting, as I had just shut the engine down, and I was fiddling with the depth sounder (another story... blasted transducer...). The chartplotter (Garmin 2006c) and VHF were also on, although not doing anything special. Nothing unusual really, although the tabs do draw a fair amount when retracting (but I had been using them regularly, which is the same draw, and all is fine. Plus, my friend and I wired them, so there is no mystery there. [Edited to add: Looked this day up in the log. We were drifting in a pool in Labyrinth Canyon, just enjoying the quiet, when the depthsounder transducer started reading "2.3'" -- which it has an annoying habit of doing at random times. I had figured out that sometimes putting the boat in reverse, then going into neutral, then shutting off and turning back on the depth sounder would "shake it loose," so that's what I was doing. I had all the instruments on the whole time, but the engine shut down. Then I started the engine, reversed, shut it off (trim tab auto retract went into action) and was just reaching up to cycle the depth sounder on and off when "all went black." I may have had my laptop plugged into the cigar lighter charging (computer off and not same plug/adapter as in the current iteration.) I didn't write that in the log, but we had been adding up power and thinking that maybe, maaaaybe, things could have got slightly close to 30 amps with any surge from the trim tab retractor firing up - as events today proved, that was not the issue).]

System info:

The way my system is wired, current goes from the house battery through a Blue Sea Safety Hub (which has a 30 amp fuse in it; the one that blew), then to the battery switch (Blue Sea On/off/combine -- the combine is for emergency paralleling; normally the switch is just left "On" while boat is in use). From there power to a positive bus (has a wire to the trim tabs with 20 amp inline fuse; plus one wire going to helm for helm stuff (original wire, 10 gauge I think.)

(The bilge pumps go straight into/out of the Safety Hub and don't involve that 30 amp fuse.)

Not sure if there is any other info that would help, but moving along with the problem....

So, the day that first fuse blew, we put in my spare 30 amp fuse and went merrily on our way. I did disconnect the trim tabs auto retractor at that time - mostly because I find it annoying and not a function I really need (it's noisy and goes on for 15 seconds, trying to retract, even if they are already retracted - I want peace and quiet when I shut the engine down).

Now it's a week later. We've been running around using everything - and all has been fine (except that depth sounder transducer..... but that's another thread - I don't think that's an electrical issue anyway). Today we pulled up to one of the "potti islands" on Powell and tied up. I shut down the engine but left the chartplotter/depth sounder/VHF on. My buddy had his phone plugged into the 12 volt cigar lighter outlet. Nothing else was on (heck, we hardly have anything else). We went about our business on the dock for a half hour or so, and then came back on the boat while I checked a few things online (computer not plugged in; just running on its internal battery). At one point we noticed..... hmmm.... the instruments are all off - no power to any of them. Pulled the replaced-last-week 30 amp fuse from the Safety Hub and... it's blown again. Now I'm really motivated to figure this out because okay, once could be a flawed fuse, but twice? I don't think so. And before I was thinking "well, why was there a 30 amp fuse chosen in the first place; maybe a 40 would be more appropriate? (Not that I just "raise" fuse sizes willy nilly; I would have researched it; just that I don't know why 30 amp was chosen initially).

But okay, sitting at a dock with nothing much on, shouldn't blow a 30 amp fuse, even if a 40 would be better in the grand scheme of things. We were tied up on a calm day, so not really even agitating anything.

I did find that there is no fuse on the wire leading to the (I believe original installation) of the cigar lighter outlet, so that will be remedied (I had already bought new Blue Sea versions anyway). But I can't exactly understand how that would have blown the fuse (that said, I'm no Reddy Kilowatt).

We put an electrical meter across the fuse contacts and then turned on the instruments that were on at the time, plus had the phone plugged into the cigar lighter (so just how things were when the fuse blew this time). Total draw: 2.5 amps, just like you would expect. I wiggled the USB adaptor that was in the cigar lighter just to see, but... no change.

So... what could blow a 30 amp fuse while we sit tied to a calm dock with the VHF/depth sounder/chartplotter/phone charger on and nothing else? (Before at least we were "doing" several things including the trim tab retractor which is over 10 amps.)

And... how do I try to find this? We can get back to the launch ramp if we need to, but.... were planning another night/day first, and plus, now the boat is effectively "broken." Noooo! That does not give me a warm fuzzy feeling.

Thanks ahead for any help or ideas you can give me.

Sunbeam (partly cloudy now)

[ghone]

Hi Sunbeam. Good write up sorry about the issue. First thing on my mind when things have been running well for a long time and then issues show up is.....what did I add to the load lately? Or what did I push into the lazarette to dislodge a wire? Anything fall off the panels behind the helm? A lotta wires in there. Anything new aboard plugged in? It's likely a wire loosened up or a poor crimp perhaps. As usual start at the batteries and trace each wire for firm connections. Anything worked on at panel or breakers where a wire forgotten? Those auto retractors are gimmicky in my humble opinion. They haven't been super dependable. I power off instrument prior to engine start to avoid spikes in voltage. Maybe? I'm suspecting the charging laptop, thru an inverter or 12v? With all the draw you may have pulled too much. Fridge on too perhaps? Maybe an old battery on the house side getting erratic? Maybe switch to start battery as house for a while to see if the problem re occurs. Alternator putting out too much all of a sudden? Don't panic I'll bet it is minor once located. Enjoy the day. George

[Ray]

I will think a bit more on this, but at first glance....

30A is *A LOT* of power. It is not likely due to one too many USB chargers or a specific mode of a VHF or anything. As you found out, these things are 1 or 2 amps at best.

If something is blowing a 30A fuse, something big is going on - something that you may be glad is fused in the first place.

I would look for a gross problem - a direct short (or close to it) somewhere. Something intermittent in the DC power system?

Maybe try to CAUSE the fuse to blow by, for example, starting the engine, moving the battery switch to all positions, fiddling with the DC panel, messing with battery connections, etc. Maybe keeping a current meter in line with the battery lead(s) to observe any anomalies....

Just some thoughts - curious to hear the outcome!!!

Ray.

[Will-C]

I would start by running new wires directly to the battery for your 12vdc outlet with an in line fuse rated to match the proper sized wire. I have a male plug for our 12vdc outlet with foot long pig tails for power should something else soil the bed so to speak electronics wise so I could temporarily power a device/s or two ie. radar, gps, vhf until I could isolate the problem . Maybe you have some mice aboard who has chewed up some wire insulation causing an occasional dead short. I would think that most of the individual items have their own lighter amp rated fuses. I'd be looking for a loose wire on a larger sized wire or cable. Maybe a whole buss bar in a fuse box is getting shorted Thirty amps is a pretty heavy fuse and would just seem to me to be related to items that have heavy gauge wire running to them. 12 gauge wire I think is only rated for twenty amps. Just a thought.
D.D.

[Sunbeam]

Hi again,

Thank you so much for responding. It means so much to have the C-Brat gang "on my side" giving suggestions and thinking it over "with" me.

Let me answer some of your questions, but first, tell you what my buddy and I have done in the meantime.

I first made of a list of every electrical item on the boat (around 20 - yay for simple boats). Then we traced each wire to see if it had an inline fuse, where said fuse was located, and what the amperage was (I will check to see they are correct later on, just because).

Every wire was fused but one. Some with fuses a bit larger than necessary, but nothing out of line. The one unfused wire was the cigar lighter. That has been unplugged for now. The only other glaring weirdo thing (not that it's the problem) is that the fan wire was spliced into the VHF wire and they were fused together. I'll change that later on.

On to some of your thoughts:

1) The heavy cabling to the batteries was all new Ancor put in by me last summer. That's not to say I'm infallible (hardly!) but just to note that it is not old or cruddy wire. Likewise the battery switch, safety hub, ACR, batteries were all new then. I can't switch the batteries around because I have a large, deep cycle house battery and a smaller cranking start battery (but I also think that this means my electronics are isolated from spikes when I start the engine). Essentially all the electricals in the lazarette are new. The wiring behind the helm is as-came (but I don't think there is anything "huge" back there, and that is what we just traced) (not that it is perfect - far from it and it is on my list to "sanitize" in future).

2) I have not added anything new since before this trip (been out a month as of today, running/living aboard). I did add the trim tabs, new depth sounder transducer, new lazarette electrical system/batteries/monitor in the past months, but those have all worked fine up to now (of course everything works fine until it doesn't....but I just mean those were not just added in the last week).

3) We did have one mouse on the outside of the boat, but (thank heaven!!) it never got inside (I barricaded the boat until the mouse was gone) and there is no sign in the lazarette (I combed the thing regularly, no turds, no sign - I detest mice).

4) The lazarette with the electronics has not been opened except to check it for mice and/or change the fuse. There is nothing stored in it - it is only to house the batteries/electrical. I like to keep that locker "clean" and uncluttered just because it is the electrical lazarette. Nothing in there is not strapped or fastened down (or should be!)

5) As far as loads.... the first time I had just shut the engine down and the tabs retractor was running, plus the chartplotter/depth sounder/VHF/cigar lighter.

Today the boat was shut off and nothing was on except the chartplotter/VHF/depth sounder/cigar lighter. So same as last time but this time the boat was just sitting tied to a dock, and the trim tabs were not in use at all ( (I disconnected the tab retractor last week when the first fuse blew -- so it is not a current player.)

6) I have not wiggled every wire - that is a good idea. We have no more big fuse (used the spare - of course MORE spares will be on board in future), but we can jumper that with the voltmeter and try wiggling things.... I think?

Funny, because the boat never even had a "big" fuse before I re-wired it. Now I'm wondering if it's a good thing - I guess it must be and maybe I avoided a worse fate.

I do have a brand new Blue Sea cigar lighter new in the package aboard - so maybe I can rig that up temporarily to charge my laptop if necessary. (Kicks self for leaving all spare wire spools and etc. back in the van when lightening up load - pack rate may be hard to stop next trip )

Again, I really appreciate your thoughts and input. Thanks!

Sunbeam

[therevdr]

For several years I have intermittently had the top three circuits on my main
(factory installed) switch-and-fuse array go out . . . you might be able to tell by my precise description that I don't know much about this stuff!!!.
WHAT I DO KNOW IS . . . the those switches are set-up in in chain-like sequence (with wires jumping from one switch-fuse station on down the line); and so, when the pounding on the black switch array no longer works, it is necessary to jiggle-and-reattach the wiring at the back of the array.
[My usual failure is for the horn, anchor light, and running lights (which is also the instrument lights at the helm) . . . which are the top three circuits on
that board.]
THEREVDR on Driftwood Drei
2002 22' Cruiser

[Sunbeam]

A bit more info. NOT that I "expect" anyone to slog through it, but more for the sake of completeness (and for anyone who does want to follow along).

We went through the electrical lazarette one more time with a fine-toothed comb. Wiggled and looked at all the "big" wires (all tight, no obvious issues). Double checked for no signs of mice (none found, no turds, no dust or dirt or piles of wiring insulation). The locker is pretty clean and white, so easy to see if anything "new" in there.

I have no fridge or anything else that would have "come on on its own" that I can think of. So my current thinking is that maybe it IS that cigar lighter plug. I think we had something plugged into it last time (I did not write that down, but buddy remembers it as my computer was plugged in charging); this time his phone/tablet were plugged into it. Occam's Razor says it would not be both my inverter and his USB adaptor, but the unfused cigar lighter was implicated both times.

If I don't find anything else, I think (does this sound like a good plan?) I'm going to wire in the new Blue Sea socket I already have, with proper wire and the right size fuse (for now it is disconnected), then put in a new (as yet to be purchased) 30 amp main fuse, and basically wait to see if it happens again.

Here, for the sake of it, is my list of all electrical items aboard, where they are fused, and what size fuse (maybe this will help someone in future). I laid hand on all these earlier today. I will check them against equipment mfg'rs recommendations later.

1) Sidelights, all around light, and compass light (10 amp fuse on factory fuse block).

2) VHF antenna (not "electrical" in the load sense).

3) Cabin lights (one fixture in V-berth, one in cabin) (10 amp fuse on the factory fuse block)

4) Fan (spliced into VHF wire and thence to 10 amp fuse on factory fuse block - this will be improved).

5) VHF (10 amp fuse on factory fuse block)

6) Depth sounder (3 amp fuse on factory fuse block)

7) Depth sounder transducer (does not draw separate load but comes through depth sounder above helm; see #6)

8 ) Chartplotter (5 amp fuse on factory fuse block)

9) Chartplotter (GPS) antenna (1 amp inline fuse)

10) Cigar lighter (unfused - ugh - looks like 12 gauge wire).

11) Trim tab switch (indicator part at helm, not relay) (two wires both with inline 1.5 amp fuses as specified).

12) Trim tab relay (20 amp inline fuse on way to positive buss in lazarette).

13) Trim tab HPU (comes off relay; see #11)

14) Auto pilot (15 amp fuse on factory fuse block)

15) Bilge pump manual switches (auto is wired directly to power, not through the blown 30-amp fuse at all). (Mid pump manual switch has 5 amp fuse on safety hub; transom pump manual switch has 5 amp fuse in factory fuse block.)

16) Cockpit spotlight (10 amp fuse in factory fuse block)

17) Victron battery monitor (1 amp inline fuse as came with product).

18 ) Horn (10 amp fuse on factory fuse block)

Thanks again for all ideas - even if I "refute" them it's just to provide info and clues - not to say any ideas themselves are not helpful!

Edited to add:

[AstoriaDave]

Sunbeam,

I agree with Ray. 30 A surge is pretty substantial. An ammeter inline during testing is a good idea, but make sure it can handle a 30A surge. Good on ya to have that 30 A fuse on the main supply! Two suggestions:

1. If easy to do, replace that 30 A fuse with a same amperage marine breaker. Blue Sea makes some which are compact, easy to reset, and show clearly when they have been tripped.

2. If there was a short somewhere you may see a damaged wire, if it was smaller diameter (altered color of insulation, etc.). Or, a spot on a crimp that shows melting. A thorough visual check, which you may have already done, sounds like, will buy peace of mind, and perhaps identify wires which need chafe protection.

The intermittent nature of the problem suggests a wire that swings or slaps into trouble.

[AK Angler]

First: The 30A fuse is there to protect the wire from an overload scenario that could cause a fire. Please don't consider bypassing that fuse because it's blowing. There's definitely a problem here that needs fixed, and bypassing the fuse could be catastrophic.

Second: With the electrical loads you have, the only real way to pull enough current to blow that 30A main fuse is if there is a short to ground. And it is likely a short in that main house wire.

Your secondary circuits should all be fused with much smaller fuses (maybe up to 10 amps for most circuits, or 20 amps for big loads like trim tabs), which would have blown if there were problems "downstream" of the main fuse block. (If you discover any un-fused circuits, now is the time to address that.)

But, if one of the wires in the secondary or tertiary circuits did happen to be un-fused (or over-fused) and was drawing that much current, they would very likely have melted some insulation at this point, and should be easy to identify as the bad circuit.

So, if it were me, I'd start looking for wire chafing, or otherwise compromised insulation on the main wire (and others, while I'm at it), especially at any locations where the wires may come in contact with anything hard and relatively sharp. I would also make sure that all secondary circuits are fused, and that those fuses are properly sized for the wire they are connected to. And, I would take a good hard look at that 12v plug for any corrosion or other irregularities in the outlet.


EDIT:

[Sunbeam]

Hi again,

Thank you for the continued, valued input. Now that I have some juice back in my laptop, I thought I would write about what we have done for now (until we get back to shoreside supplies tomorrow).

1) I won't be removing the 30-amp fuse, but thank you for confirming that it's a good idea. I did so some research before putting this system in, but certain parts of it I partly "took on good faith" from experts were a good way to go. So it's good to have confirmation of that.

2) I removed the original cigar lighter fixture, and put in place the new Blue Sea one I had brought onboard.

3) So now to fuse the wire (and I drastically lightened up my electrical kit, so did not have much here with me). I had one empty fuse block on the factory block behind the helm, just adjacent to the cigar lighter. This had a 20 amp fuse it it and was used for the washdown pump, which I temporarily removed from the boat until I finish re-doing my water system. I took that out and put in a spare 10 amp fuse I had aboard, then re-used the spade connectors that went to the original cigar lighter fixture on one end, then used a butt connector I had aboard to connect that to the spade connectors that were on the fuse block terminal. So this means there is a new cigar lighter fixture, and the original wire but that wire is now 10-amp fused. I will not plan to use it much until I re-do it all, but wanted to be able to charge my laptop at least partially.

4) Okay but we still have no power to the boat (except the engines and bilge pumps which do not run through that fuse). First of all, did we need it? What are our options?

a) We are safely tied to a "potti island" on Powell, and I doubt there would be a problem if we stayed here overnight, so that is one option.

b) We could have gone to anchor in a small cove nearby, or another anchorage we have used already and "know." We have an LED lantern (actually two) that we power with AA batteries (lots to spare) so we could have fashioned an anchor light (although they are not used much here anyway, as people are usually tied to shore or near shore).

c) We could have made it to the launch ramp during daylight if we had really wanted to. We know the way and could have just followed the main channel even without chart or depth.

d) We have a freshly charged tablet with Navionics on it.

That said, we were not planning to "take out" until tomorrow, and our vehicle is in storage for which we need to make arrangements to get a ride to. So taking out today would not have been handy. But we could have taken a slip too, if necessary.

Instead, we decided to rig a temporary solution to be able to use power. I will not use the trim tabs or autopilot, and nothing else we have draws nearly as much as those two items (we can monitor draw underway via the Victron battery monitor).

What we did was use one of the "upper" terminals in the Safety Hub (uses a car style flat fuse -forget the name - and not the "big" type - forget that name too at the moment), and put a 20 amp fuse in it (the former washdown pump fuse rides again). This is now powering everything (but as stated, we will only use lower draw items, and we are prepared for it to "go south" again. Tomorrow we'll haul out, and these items will be addressed before boating again.

Okay, better head to the anchorage as I would like to get there during daylight, just in case.

Sunbeam

PS: If the cigar lighter was the culprit - yay! But I will still spend some time looking over every wire. I have tried hard to chafe guard everything, but the fact remains that there is still much "factory" wiring on the boat that I have not re-done. On the other other hand, this last "blow" was while the boat was sitting motionless, so maybe it is (was) the cigar lighter....

[AK Angler]

You should be fine running your basic navigation circuits off of the temporary 20A fuse. (Good workaround, by the way. )

I would suggest putting a piece of tape over any switches that run the big power draw circuits (trim tabs, auto pilot, etc.) so that you don't use those systems out of habit and end up popping the temporary main fuse.

Good Luck!

[Sunbeam]

[AK Angler]

Well, if it wasn't the 12V outlet, you'll find out soon enough.

But... since it was the only non-fused load running through the main fuse, I'd bet dollars to doughnuts that it's either a ground fault in that 12V outlet, or the main house feed is shorted to ground. (My money's on the outlet.) The short 12g non-fused wire powering the 12V outlet could certainly carry a ground short long enough to trip the 30 amp fuse at the SafetyHub, without melting the insulation off of it.


And as a side note (because you mentioned the splashwell boot), last year I found a trim tab wire (that has a very thick outer insulation protecting the inner insulated wires) almost rubbed through where it went through the hole in the splashwell on my Arima. It's a good area to keep an eye on.

[anchorout]

Sunbeam:
I have many yrs experience in electronic repair. I know, we all find it hard to believe that something could short out on a boat tied to a calm dock. We call it FM F......g Magic in the business and I assure you it happens. A change in temperature causes a wire to stretch or shrink. A change in humidity causing moisture to drip into a component. Vibration. The boat hull itself reacting to heat or a passing boat's wake.

Intermittent shorts are very difficult to find until they finally short long enough to trace them with a meter. As the other Brats have said, to blow a 30 amp fuse you need almost a direct short. Obviously, the short will be AFTER the fuse, not back towards the battery source. You have isolated most equipment with appropriate fuses. You have turned most items off and had the master fuse blow, that tells me it is not from having to many devices drawing to many amps. Look for wires NOT protected by secondary fuses. Look for wires where +12v and Ground may be switched (your cig lighter plug should have +12v on the center terminal). Look for old wires that have been snipped and just tucked behind the bundle, where they can touch ground. The problem may be behind the fuse panel itself, a broken terminal or stray piece of wire or loose washer sliding around. Check between your hot panel and ground strip, nothing flopping between to short them together. Also, a sloppy crimp where the insulation gets into the crimp, or a loose crimp or terminal which can cause a surge or spark which will blow your fuse.

You say you have not checked out the older wiring circuits. Isolate the ones not protected by fuses. Pull them off of the terminals, label and insulate each until your problem goes away. Then connect one at a time until the problem returns.

I hope you find this problem soon, but if not, a temporary 30amp breaker, as others suggest, will make life easier in the mean time even if you just hang it to one side with a tyewrap. Typically these type problems increase in frequency and become easier to find. I hope I have helped.

[ghone]

Hi Sunbeam. Since this is your main fuse I'm wondering if it is on the small side. I would like the main protector to be a resettable breaker. Like in airplanes reset it once and then investigate. Mine was wired with a Blue Sea breaker (pretty sure it's 50 amp). The boat is in the canvas shop so a couple days till I can check. It's the same breaker as the windlass uses 50 amp. Alternator on the Yamaha 90 puts out 25 amps. I kind of think that laptop into the 12 ga socket is part of the issue though. Best of luck. George