Mystery electrical system problem - not sure how to proceed.

[Sunbeam]

Is it possible that you have a problem with one of your cables? Internal decay or a defect could cause it to heat up under load and possibly blow a fuse.

Although anything is possible, I'm guessing no at this point. Reasons being that the cabling is all new within the past ~year, the boat has not been in salt water, and the problem definitely occurs just when the ACR flips into "isolate" mode (OTOH, if we manually isolate, or if things are isolated already, then nothing problematic occurs). The problem does not occur when the ACR goes to combine.

So, we'll leave everything as-is for now (so as not to change more than one variable), put in the new ACR, and see if the problem changes. I hope it does, but if not, then we'll go back to sleuthing.

I think what we're talking over now is more how I can improve my overall layout (at least I think that's what is happening now). I welcome the input, and am shaping my idea of how to rearrange things to make it even better. Actually, I can't wait to dig into the area behind the helm and make it all neat and tidy.

Ray,

I see what you are saying with the way I have the main fuse on the battery side of the switch. (But there is only one 30 amp fuse, in the Safety Hub; the ACR wires, which are 6 gauge, do not have fuses.) In my case neither battery has ever been low at all, and there has never been any problem or fuse blowing when things go to "combine." But.... I will be moving the main fuse to the "other" side of the main switch so as to avoid this possibility in future, so it's good to have found it out.

Sunbeam

 

[anchorout]

Sunbeam:
The only thing I question is the way the battery monitor shunt is wired. You are creating a potential (much as a highly corroded terminal might do) between the two battery grounds. This could create all sorts of problems when you switch or eliminate one of the batteries. Might I suggest you tie both battery negatives to one side of the shunt, and the ground plane to the other.

 

[anchorout]

The computer cut my edit off.

Sunbeam:

I am headed to the Gulf Brat Gathering, but when I get back to my boat, I,ll see how the shunt is wired on it and get back to you. The way the schematic is wired, the shunt is only monitoring the charge through the house battery. That battery is always on line so that would work, but the accuracy would be in question as the current is also splitting to the starter battery.

 

[Sunbeam]

Ray,

Looking at the ACR instructions, I see what you mean about the fuses in the ACR cables. I had this installed by a tech (a while back now), and at the time I didn't really understand enough to question how it was done, which was without fuses (although interestingly, the Blue Sea tech person didn't catch it either). So it looks like I need a 75-90 amp fuse in each of those #6 cables leading from "A" and "B" on the ACR to the two "cold" sides of the battery switch. Duly noted (my lazarette is going to be like a fuse depot!). I guess I may finally get a crimper for #6 battery lugs.

Sunbeam:
The only thing I question is the way the battery monitor shunt is wired. You are creating a potential (much as a highly corroded terminal might do) between the two battery grounds. This could create all sorts of problems when you switch or eliminate one of the batteries. Might I suggest you tie both battery negatives to one side of the shunt, and the ground plane to the other.

anchorout: As I understand the Victron BMV-600S, it's meant to monitor one battery (or one bank). The BMV 602S is for two banks. I don't have a desire to monitor my start battery, so I chose the house bank as the one to monitor (in this case the "bank" being just one battery). I think this is what is shown in the installation manual here:

http://www.victronenergy.com/upload/doc ... 7-2007.pdf

I annotated the diagram again to show more detail on the battery monitor circuit.



Sunbeam

PS: I can't recommend the battery monitor highly enough.

 

[anchorout]

Glitch

 

[Sunbeam]

Can't afford it. I'm already buying a safety hub.

 

[anchorout]

One good thing, now you know that you should be able to run the boat on ""combine" and not blow the house fuse, as the ACR would be out of the circuit.

 

[Ray]

I don't have a desire to monitor my start battery, so I chose the house bank as the one to monitor (in this case the "bank" being just one battery). I think this is what is shown in the installation manual

I have my monitor connected exactly the same way, Sunbeam. This is a very typical single-battery setup.

 

[AstoriaDave]

Sunbeam,

That looks good, with the same caveats Ray identified. Your plan to move the safety hub with its 30 A fuse to the other side of the main switch, will remove both.

My only reservation is that later you may decide you need more capacity for some rare, "emergency" set of conditions, as I mentioned earlier. However, with the safety hub past the main switch, using the two safety hub terminals which bypass the 30 A fuse, add ons (separately fused) could solve that issue. The existing 10 ga wire will be unused after you go to 6 ga for the main feed to the helm, so there is some capacity there ... don't recall what you calculated for maximum load on that wire. In lieu, with 6 ga wire coming off the safety hub, is there any reason you can not increase the rating of that fuse from 30 A to a higher one, feeding add ons from the positive buss?

The problem of a surge of current from a fully charged battery flowing to a nearly dead battery through that 30 A fuse will be moot when the safety hub is moved.

 

[thataway]

Sunbeam, when leaving the boat for any length of time, disconnect the + battery cables. If the boat is in the water, then the bilge pump auto circuit would have to be left connected. I have never had any issue with ACR depleting the batteries over days.

Ray, you don't run with the switch on combine, that is why there is the ACR. Pretty much established that a surge when the batteries are combined thru the ACR, that could blow the 30 amp fuse. Looks as if this has been changed.
Only Sunbeam knows exactly how this is wired.

Ref. the tt relay, if you put it on the diagram should be shown properly.

I suspect we will see the corrected, or proper diagram to avoid these issues.

Sorry I can not draw diagrams from the I pad...

Back to the Gulf Coa st gathering.

 

[Sunbeam]

Sunbeam, when leaving the boat for any length of time, disconnect the + battery cables. If the boat is in the water, then the bilge pump auto circuit would have to be left connected. I have never had any issue with ACR depleting the batteries over days.

Now that I re-wired the ACR, I don't seem to have any drains at all, so just turning off the battery switch does the trick. When I noticed the drain before, it was over weeks/months, not days. I forget how much they said it was, but it's very small. I actually thought it might be something else at first. But then someone (I forget whom) mentioned that the ACR would constantly draw a small load, so I called Blue Sea and asked about that. They said that yes, it does. Then they suggested a couple of ways to change that, the way I wired it being one of them. Now the batteries basically stay just how I left them.

It would be unhandy for me to disconnect my positive battery cable (vs. turning the switch to "off"), so unless there is a problem with it, I would prefer to leave that part of it as-is. Once I move the main fuse to the "downstream" side of the switch, is there a problem with the way I have the ACR wired?

Ray, you don't run with the switch on combine, that is why there is the ACR. Pretty much established that a surge when the batteries are combined thru the ACR, that could blow the 30 amp fuse. Looks as if this has been changed.
Only Sunbeam knows exactly how this is wired.

I think it's wired just how AK Angler drew it in the diagram. I do hear what Ray and others said about what could happen (in the future) if I left the main fuse on the "upstream" side of the switch. That's why I plan to move it now. That said, as far as the "mystery" goes, that wasn't the problem. i.e. up to this point in time, I have not seen any problem with the main fuse when either the ACR or a human combined the batteries (rather the problem occurred as it switched itself to "isolate." But as I said, I see the value in avoiding the prospect and am glad it was brought up. Why miss the chance to have expert C-Brats help me to improve the overall boat? I'm looking at it as an opportunity.

Ref. the tt relay, if you put it on the diagram should be shown properly.

I'm not sure what's incorrect there now, but I'd be happy to fix it. Initially, AK Angler was asking about the components that were potentially involved in the "mystery." At that point in time the trim tabs had been cleared of any involvement (and were actually disconnected), so I may not have noticed that they were not shown 100% correctly (in my mind it was kind of like the line that trails off to "house loads." However I believe we did notice and fix that subsequently (he added a part, and then I added the inline fuse in the drawing above). If it's still not clear I can try to modify it again -- I'm not an ace electrical artist, that's for sure.

Back to the Gulf Coa st gathering.

Sounds fun :thup

Sunbeam

 

[Sunbeam]

I'm sure so many of you are just thinking "Gee, it's been hours and no post in the electrical thread - what ever will we do with our time?" :wink

I'm waiting for the new ACR (due to the weekend it will not be here until Monday :cry), and in the meantime - between bouts of cleaning and carb draining and such - planning out how to modify the electrical system (not because of the "mystery" problem, but because, over the course of the thread, I've learned more and - thanks to you all - found some areas that could be improved upon).

I have worked out a way to rearrange things to put the main fuse (or maybe I'll change it to a breaker) on the correct side of the main switch, and that's perfectly doable (with a few more Blue Sea goodies, of course, but I can handle that).

But I'm also re-evaluating whether I even want the ACR at all. I had it put in as sort of a given it was the way to go, but now I have a chance to re-evaluate. It is handy, and even though one seems to have been defective (we'll find out for sure on Monday), I know the odds are that I won't have another failure.

It definitely makes for more wiring components and complication (although once they are installed they basically just sit there, and it's not like I'm going to be using the lazarette for anything else anyway). But OTOH, there is a certain satisfaction in simplicity and in fewer "black boxes." And I'm typically good at adhering to an established routine aboard (such as manually moving the battery switch).

So... not sure which way I'll go yet, but I'm mulling. I won't be changing anything until at least Tuesday because I want to put in the replacement ACR without changing any other variables, so I have time to think it over (and to add or subtract things from the shopping cart).

Sunbeam

 

[ghone]

I was wondering how to fill my day!! My boat is in the canvas shop till tomorrow so I'm following your thread. I don't have the ACR, my boat was factory wired and a nice job was done. Circuit breakers and few black boxes. I like hard wired to buss bars and battery switches and keep it simple and easy. With only two batteries aboard and only one house battery it's easy to keep track of for me. So no ACR for me. Hope it's the issue for you. George

 

[Sunbeam]

Update:

Thanks to Blue Sea's great customer service, the new ACR arrived today via UPS, along with a call tag for me to send the original one back.

We got right to it and "out with the old; in with the new," plus, as long as we were at it we installed the recommended 10 amp fuse on the ground wire. I purposely haven't made any of the other changes because I didn't want to change more variables. I'm not going to be using the boat again right away, so I have some time for that going forward.

So, we had purposely not charged things up too high, because we wanted the voltage to be close to the ~12.75 that is where the ACR combines and isolates, for testing purposes. So for starters we put the charger on until the voltage got to about 12.86 and we saw that the ACR "combined." Then we turned on the GPS, VHF, and depth sounder and watched the battery monitor as the voltage dropped. When it got down to around 12.79 my buddy went out and watched the ACR like a hawk while I called out the voltage readings. Sure enough, right at around 12.75 the ACR isolated, as it should (and as the old one did). The difference being that.... nothing blew! Then we did a repeat and.... still nothing blew :thup

Now, of course we can't be 100% sure this is solved; but since the original ACR was blowing a 10 amp fuse consistently as it switched itself to "isolate" (toward the end), this is a very good sign. I feel hopeful we have solved the mystery. I think Blue Sea is going to test the original ACR, and I'm very interested in what they might find.

********

Next up: I'm going to decide whether or not I want to keep an ACR in the system, or go manual. Either way, I'm going to move the main fuse "downstream" of the switch, plus tidy up behind the helm and run a larger gauge feed wire to accommodate future draws (and then adjust the main fuse size accordingly). If I keep the ACR, I'll be adding two fuses (one in each wire, A and B), plus wiring up the start isolate feature to the engine start wiring. I have it sketched out and a list of what to acquire, but.... going to think about it a bit first.

*********
And one "oopsie!" to explain. I think it was earlier in this (book length!) thread that we talked about engine charging and SOC. I had noted that my engine seemed to get the batteries up to 100%... but from everything I had read, the charger on an outboard is really too primitive to do that (more typically it will get up to 85%, if I understand correctly).

That nagged at me, and I started going back over everything with my buddy, and finally the penny dropped: When we got out on the water, both he and I had lots to do ("new" boat/gear stuff), and he happened to be the one who calibrated the Victron (easy to do, but it's calibrating it that gives you the SOC percentage baseline). Well, he didn't realize that an outboard really never gets the batteries up to 100%, so he waited until the battery wasn't accepting any more charge (from the outboard) and then calibrated it to be full (which is basically what one does). So no wonder my outboard seemed to be that one special flower that charged like a miracle. Glad I kept the SOC up for most of the trip (so that even with the mis-calibration I was not under 50%).

So, I think we'll have to re-calibrate after my "land" charger gives it a "real" 100% charge (easy to do though).

Thanks for "coming along" on the mystery tour I will update as/when any new information comes my way.

Sunbeam

 

[AK Angler]

Well, that is exciting news, indeed!

And although I can't figure out what kind of internal ACR failure would cause that fuse to blow, I fully admit to being ignorant about such devices - I just don't know how they work. But, it does appear that the new unit has solved the problem.

And, I'd certainly be interested to hear what went wrong with the old ACR. But, I doubt we ever will... Manufacturer's usually don't advertise that kind of stuff.

 

[Sunbeam]

Well, that is exciting news, indeed!

And let's hope it stays that way through further use/testing (which won't be for awhile).

And although I can't figure out what kind of internal ACR failure would cause that fuse to blow, I fully admit to being ignorant about such devices - I just don't know how they work.

I hear you. And it's not even like you turn the thing over and see "stuff" on the back - it's just a blank black surface. I think they said there are a couple of relays inside, plus... a circuit board? I kind of wanted to saw it in half and look!

And, I'd certainly be interested to hear what went wrong with the old ACR. But, I doubt we ever will... Manufacturer's usually don't advertise that kind of stuff.

True, but I'm going to get in touch with them and at least ask. And heck, I don't expect every electrical device to be perfect - some of them have to have failures (and now I actually hope this one did). I'm just so curious what they will find. They certainly were great about exchanging it for me (and having your electrical diagram when I was on the phone with them was great).

Sunbeam

PS: And just for the (ongoing) record (added fuse in ACR ground wire). I'll probably have to come up with a new drawing for the next iteration - might be beyond annotation.

 

[C-Nile]

This is a very valuable thread for people with Blue Seas ACR's. Thank you.

 

[Sunbeam]

This is a very valuable thread for people with Blue Seas ACR's. Thank you.

I'm glad you found it useful. I sure learned some things (such as, even if a pro hooks it up, double check things against the instructions and diagrams and at least get a handle on why things were done the way they were; and.... lots about how to improve my behind-helm wiring). Presuming I keep the ACR in the system, I'll be adding some fuses and rearranging a few things.

I really do hope Blue Sea can/will test the one I'm sending back, because if it is defective, well wouldn't that be a nice "for sure" relief. If it isn't.... well, let's cross that bridge if/when we need to :smilep

Blue Sea as a company came through with flying colors though, in my book :thup

 

[AK Angler]

PS: And just for the (ongoing) record (added fuse in ACR ground wire). I'll probably have to come up with a new drawing for the next iteration - might be beyond annotation.

It wouldn't take much for me to clean up that drawing if you want a clean schematic before you start making changes. Let me know if you think it would help.

 

[Sunbeam]

It wouldn't take much for me to clean up that drawing if you want a clean schematic before you start making changes. Let me know if you think it would help.

Thank you so much - I'll keep that in mind when I get to re-arranging :thup