Mystery electrical system problem - not sure how to proceed.

[Sunbeam]

Thanks again. I knew how the switch worked, but I wasn't sure if the drawing was showing that - now I see it.

Now just to satisfy my own curiosity I will have to see how I did ground the trim tab relay - with the HPU wire or separately (HPU wire may have been a bit short.... I can't remember because I changed the relay location after I figured out a better place for it (back when I was putting it in). I believe it's all the same electrically though. That will be tomorrow in warmer daylight.

Good suggestion on the diagram and Blue Sea - I'll see if I can e-mail a copy to the tech person for when we talk - that should be a lot better than trying to "tell" how it is. I'm really curious to hear their thoughts.

At this point it would be "easy" if it were just a defective part (although finding it.... not so much!).

Sunbeam

PS: Hmm, I found something interesting. Thing is, I keep thinking it's *much* more likely that some mistake was made than it is for the ACR itself to be defective. So I read the directions for the installation of the ACR just now again. But this time something jumped out at me:

Minimum connections for operation:

• Connect one battery bank to stud terminal A.
• Connect the other battery bank to stud terminal B.
• Connect the quick connect terminal marked GND (ground) to the DC system ground through a ten to fifteen amp in-line fuse to prevent fault currents from flowing in this wire.

I will have to look in the morning, but I think I may not have an inline fuse in the ground connection wire. I have a feeling it is connected directly to the negative bus. I didn't wire that part, so I'm not positive, but I can't "see" an inline fuse there in my mind. I don't know exactly what "fault currents" are, but.... maybe they are what is causing my problem?

Heck, who am I kidding. There is no way I can sleep wondering about that! :dons jacket and headlamp to go look now:

PPS: Just checked: no inline fuse. So maybe "fault currents" are what is causing the ACR to blow fuses when it clicks over into "isolate" mode? That would be a simple fix (which of course I will do anyway, since it's required). Ironically, when I first sea-trialed the boat after all the work, the battery wasn't charging at all (which I could see by looking at the battery monitor). Turns out the ground wire (the very same one!) was connected to the wrong terminal on the ACR. I switched that and it worked fine for the first three weeks of this trip, then the "mystery" started. Now I can't wait for morning so I can ask first my buddy (who is much more electrically inclined than me) - and then perhaps Blue Sea - if the lack of inline fuse is an obvious cause of the issue.

Then I'll see about properly wiring up the optional starting isolation.

[AK Angler]

Excellent. Now that the circuit diagram is drawn up, and everybody's on the same page, we can try to noodle through what might be happening to pop that 30A fuse in the SafetyHub. So far, I don't have a good theory, but I'll sleep on it and maybe something will come to me. (The ACR is certainly suspect at this point, but I'm not convinced that it's the problem.)

In the mean time, I have some thoughts brewing about the overall system layout. With the way everything appears to be wired, I have some concern about the circuit(s) running from the switch to the house loads (through the positive bus). If the switch were ever set to 'combine' (or if there was ever a problem with the ACR ), there would be no fuse protecting the wires to the trim tabs, or to the distribution block at the helm. They would be connected directly to both the start battery, and to the motor(s) - either of which could end up pumping some serious amperage through those wires if there were ever a short to ground in those circuits.

Just something else to consider...

[Sunbeam]

Did you happen to see my PS about the ACR ground not having an inline fuse? I don't completely understand how "fault currents" would affect things, but I now wonder if that is the problem.

[AK Angler]

Adding the fuse in the ACR's ground wire is a good idea, but I don't think that's the cause of the problem. Fuses are for useful protection from faults, but they do nothing to prevent them.

But, you just stated something that made me stop and reconsider the ACR as the root cause... Everything was good for months, and then this problem cropped up. ... ... ... hmmm ... ... ... Makes me think something may in fact be wrong with the ACR itself, and not the external wiring. I don't exactly know what all's inside of one of those things (and I'm not cutting mine open to find out!), but I do know that there's more than tiny fairies monitoring voltages and flipping switches. There's certainly electronic circuit boards and such. And, all kinds of mayhem can be unleashed when that stuff goes wonky. (I may have a pretty good handle on electricity, but can you tell I don't know much about electronics? )

Anyway, I'd like to hear what BlueSea has to say about it...

[Sunbeam]

Okay, well since you didn't immediately think that missing fuse on the ACR ground wire was the cause (and I'm not sure), I think I'll still call Blue Sea in the morning. I'll explain about that missing fuse just so they know, in case it's a clue.

By the way, I just looked at the original diagram that the electrical tech wrote up for my system, and I see that on it, the "main breaker" is on the "downstream" side of the switch (i.e. towards the helm) vs. the upstream side where it ended up in the Safety Hub. Maybe that was to prevent what you were thinking about with the "combine" setting on the switch. I think somehow when I agreed to the suggestion of the Safety Hub, that changed. Maybe I need to just change some things around now to make it "proper." I don't mind doing that at all once I figure out how it should be.

On the ACR: Just to clarify, the time period I've been using it for hasn't quite been months - just because this trip on Powell was my first real trip, save for one afternoon "sea trial" on Lake Crescent. But, it did work fine for the first three weeks of this trip, which was 24/7 living aboard/motoring/anchoring, so a fair bit of use. I actually more than doubled the hours on the boat from when I bought it! (Was 52; now around 135.)

I hear what you are saying about how "black boxes" are different than straightforward electrical.

Sunbeam

[AK Angler]

[AstoriaDave]

Pardon my naive question, but I also wondered about the placement of the 30 A fuse. I also would have expected it to be downstream of the switch, with the switch within 7 inches of the battery, and the Safety hub right next to the switch. Placing it between the positive terminals of the two batteries when the switch is set in to Combine mode means if there is a current flowing from one battery to the other, as would be the case if one battery is more fully charged than the other, then that fuse is exposed perhaps to a heavy current.

Is that possibly the problem?

What bothers me about moving the safety hub past the switch is that then the bilge pump circuit(s) will not be energized when the switch is off. I believe you want them energized (and fused) all the time, yes?

Is that Safety hub intended for a two battery system? If so, do the instructions for installation say to put it between the on/off switch and the battery?

[Sunbeam]

These sound like good questions that I need to find out the answers to. I couldn't figure out for sure by reading the instructions for the individual components, but I was just looking at some "sample systems" that Blue Sea shows on their website. I *think* they show the Safety Hub between the battery and the switch (like mine) but I'm not completely sure because (of course) none of the examples are just like mine. But.... see this one for example (the safety hub is a 150 not a 100 like mine so it looks slightly different, plus the whole thing is more elaborate). On the other hand, you can't really see what's going on inside the switch, in terms of what is where so maybe there is something I'm not seeing.

http://www.bluesea.com/systems/43/Battery_Management_Circuit_Protection_and_Switching_SubSystem

I now have a list of things to ask the good folks at Blue Sea tech help about, thanks to you all As you say, there are many ways to accomplish it - I just need to know that I have what I think I have (or if not, change it). Glad I have things mounted in such a way that I can switch them around without too much agony.

Sunbeam

[AK Angler]

One quick solution to the fuse placement issue would be to swap the SafetyHub and the positive bus in the diagram. The bilge could run off of the positive bus, and the trim tabs and helm power could then be fused off of the SafetyHub, downstream of the switch.

Or, move the Safety Hub to where the positive bus is, delete the positive bus altogether, and run the bilge pump off of the hot terminal of the 'house side' of the switch.

More than one way to skin a cat...

[C-Nile]

[Sunbeam]

Okay, just got off the phone with Blue Sea's very friendly and helpful tech support. AK Angler, your drawing worked a treat, allowing them to quickly see just how everything was set up, without a long, drawn-out description (such as I subjected everyone here to ).

So first we concentrated on the mystery fuse-blowing problem. They could not see any reason why my wiring/set-up should cause such a problem. They also couldn't see any reason why the ACR "should" act that way (it is basically just two automotive relays inside a box), but then they did agree that it does seem to be doing so.

They did ask if we had tried one thing that sounded logical and that we had not thought of to try: That is, combine the batteries manually (with the battery switch) and then "un-combine" them manually (i.e. without the ACR doing it) to see if the fuse then blew. My buddy ran out and did that while I stayed on the phone with Blue Sea. He ran several cycles and ... nothing blew.

Without missing a beat (and even though this is apparently not a "known" failure mode of the ACR), the tech person offered to send out a new ACR to me for free. Even offered 2nd Day air when I said we were going to be leaving the area and might have to wait quite a while to be "settled" at another address. That is fantastic customer service. There was no hint of "Gee, this has never happened before (and thus you, the customer, are the weirdo and we, the company are superior)." That attitude always galls me (especially when I often find out later - thanks to the Internet - that no, I'm not the only person who had X problem). Not a whiff of that from Blue Sea

Next I related my questions about where the Safety Hub is, what might be able to happen when the batteries are manually combined, and a couple of other minor things. I bridged the idea of moving the Safety Hub to the other side of the switch. Some things the tech person mentioned in no particular order (and hoping I understood them and can convey them properly):

1) As far as ABYC recommendations, there is a "grey area" in fusing for the combine function. This has to do with emergency/combine engine starting, and how it is hard to have a fuse large enough for that but small enough to work within a given system. Not that I am looking for loopholes, but he just mentioned it.

2) The tech person did mention that it would be possible (and maybe common for some installations) to have a very large (100 amp, say) fuse in the Safety Hub that would cover the "manual combine" function anyway; but then agreed that that would make the rest of my wiring (e.g. to helm) problematic to protect, so probably not the way to go on this boat. We will, however, figure out what sort of load the Yamaha main engine might draw when starting, to see what we are dealing with in that area. Perhaps my future upgraded helm wiring (say to allow a 50-60 amp fuse) might cover it anyway. This may be moot if we move the Safety Hub -- at any rate we now have more tools to use to figure out the best way to proceed.

3) But they could see why I (actually AK Angler and Astoria Dave!) was asking. We discussed possibly moving the Safety Hub to the other side of the switch (and then using some other fuse block on the battery side for the bilge pump leads). Although, by the way, having the Safety Hub where I do is a common recommendation/installation on "in the water" boats, as outlined on their site -- so it's not always just weird or wrong.

4) I mentioned that when I first put the system in, my house battery was within a 7" cable length of the Safety Hub, so I did not need any circuit protection on the wire (as per ABYC); but then when I had to change start battery sizes, I switched the position of the two batteries (physically), and so now I have a longer cable leading to the Safety Hub from the house battery. The reason I mentioned it is that if the SH were no longer providing that "within 7" fusing, then maybe one of its functions was no longer a "plus" on this side. He then told me about an exception in ABYC that I did not know (or forgot?). That is that one can have up to 72" of cabling before the fuse if it is encased in protection. I have around 27" and it is easy to get to and to see, and is a clear run, so I will put a casing around it. (I like Blue Sea's terminal fuses, but I can't fit one due to height constraints; I was going to put an inline fuse/block in, but now I guess I don't have to.)

So, the plan is to first get the new ACR and put it in with all else "as-is." Then we will recreate the "click over to isolate" moment a few times and see if it still blows the fuse (let's hope not!).

In the meantime we'll be noodling over the best way to arrange or re-arrange my components (Safety Hub, fuses, bilge pump wires, helm fuse blocks) and then order some Blue Sea goodies of one sort or another and get things polished and tidy.

I'll update as we go.

Sunbeam

[AK Angler]

Perfect!

[AstoriaDave]

BlueSea did the job for you. Good. I will be very interested in the outcome when you plug in the new unit. Keeping my fingers crossed!

Sounds like you have gleaned a lot of solid information for configuring your wiring, etc., in a safe, approved fashion. Thanks to your careful, persistent attention to the mysterious 30 Amp fuse fracas.

[thataway]

Maybe. I am missing something since I am looking at the diagram on the i pad. The ACR should be wired directly to the house battery, not thru this switch or the safety hub.
The diagram shows that when the ACR relay is closed the current goes thru the fuse on the safety hub to the house battery. This could blow the fuse, as the batteries combine.
Also when the ACR relay is closed, then the positive buss is directly connected to the start battery as well as to the house battery, and thus the positive buss is not fused properly. There is no fuse to the trim tab relay.
If the switch is put on combine, then any current from the house battery to the engine start battery will flow thru said 30 amp fuse. If you were to fuse the engine start, it should be 500 or so amps.

[Sunbeam]