Electrical Problems Redux

Pat Anderson · Posted: Thu Mar 27, 2008 9:51 pm Post subject: Electrical Problems Redux

OK, you all know the story of how I put a red cable on a black post on my starting battery and burned all the insulation off the cables, and we are not sure what all else...well, I replaced all those cables, and charged the batteries up, thought all was well...the batteries held their charge, no problem, right? Wrong.

This past weekend, we went out to Andrews Bay on Lake Washington. Right off the bat, the house battery was fading fast with little or no load on it...12.8...12.6....12.4....12.2 (house battery voltages per Navman), so, something is not right. OK, we didn't run the refrigerator at all, and we didn't run the Wallas all night per usual. In the morning, we ran the engine for a couple of hours to put some charge back on.

Tried to start the Wallas, light went on momentarily, then off, then a phenolic smell and she was deader than a doornail. I will replace the 2 amp fuse from the circuit board (not an easy item to find in podunk Snoqualmie, evidently not a standard automotive item), but from the smell I think she may be fried. Thread for a different day...

Went to leave, not enough juice in the battery to operate the windlass - solved that one, not a good permanent solution, by disengaging the gearshift and running the engine up to provide enough amps to get the anchor out.

Back home, I charged up the batteries - both went to 13+ volts. Have been measuring the voltage daily with the DVM, after a day, both start and house settled in at 12.6 - 12.7 volts (chart says that is 100%) with both battery switches off. Then I turned on the house switch with all circuit breakers at the helm off - overnight, it dropped to 12.45 volts.

The house and starting circuits go through a BEP 716 battery cluster. The battery cluster itself is an awkward assembly of four separate components, three switches and the VSR - they are sort of loosely connected but fall apart when unscrewed from their mounted position. The plastic housing of one of the switches is broken. So the problem could be in the battery cluster, or it could be in the wiring downstream of the battery cluster - there is no evidence of any melted insulation or anything downstream of the battery cluster.

I think I need to replace this guy, whether it is the source of the problem or not, just because it is physically broken. But I am not sure I want to replace it with the same thing. The literature that I got says the VSR directs all the charge from the alternator to the starting battery until it reaches 13.7 volts, then combines the batteries for further charging, then disconnects the batteries when the engine is off and the voltage has fallen to 12.8 volts. So, question number one is, what happens if the starting battery never gets to 13.7 volts? I would assume if that happens, the house battery never gets charged, right? Putting an automotive 10 amp charger on the starting battery, it in fact goes up to a little over 13 volts, but it never reaches 13.7 - this could explain why running the engine did no good for the house battery. There is another system, the Blue Sea 7650 Add a Battery, which is two separate components, one is a standard 1- 2 - Both battery switch, and the other is a relay that combines the batteries for charging. This seems like a lot better solution than the BEP switch, right? They are about the same price, and I will be getting one or the other, if anybody can tell me why getting another BEP makes any sense at all, or why not getting the Blue Sea makes sense, please let me know!

But really, the big question is, what strategy should I employ to find out why the house battery is getting drained so fast? I am thinking first just to wire up the batteries in parallel, eliminating the BEP battery cluster, since it has to go anyway...if the batteries stay up at a reasonable voltage with the switches on but no load, I can conclude the problem was in fact the BEP battery cluster. Is there any reason I should not do that? If it turns out the BEP battery cluster is not the problem, well, then I guess I need a real boat electrician, since the problem would be somewhere south of where the bundle of wire disappears under the cockpit floor... Any and all advice welcome here, I really need this solved before Friday Harbor!

jkidd · Posted: Thu Mar 27, 2008 10:31 pm Post subject: Battery switch

I have the BEP on my boat it is fine. Take your DVM and set it to amps DC, 10 amps is probally max. Turn all your switches off. Disconnect the positive lead off of one battery and connect the DVM red lead of the dvm to the positive terminal of the battery. black lead to the loose cable end. This is a series curcuit. See if there is any current draw. Do the same for the other battery. Now if you are reading current more than 0 there is something in the boat using power. The easy way to isolate this is to remove wires off of the positive buss and check for current each time at the battery leads. When it drops to 0 that circuit is the one using the power. With the battery switches on and all the helm switches off the CO detector and the Bilge pump could still be using power. If this doesn't make sense them pm me and I'll talk you through it on the phone.

hardee · Posted: Fri Mar 28, 2008 12:51 am Post subject: One possibility

Pat, this is mostly way beyond my skill level with electricity... but I found I was having a continual battery drain too. Turned out when it got dark, that even with everything turned off, there was a pilot LED in the CD/Stereo that was still on. Sure didn't seem like much of a light but unplugging the stereo stopped the power drain. Now if I could just figure out why that thump thump thumping stopped Rolling Eyes

Harvey
SleepyC

Larry H · Posted: Fri Mar 28, 2008 1:28 am Post subject:

Pat,

The first thing I would do is take the batteries to a battery shop and have them load tested. The shop will apply a resistance load to the battery and see if it is putting out the amperage it should. If the batteries are OK, then its time to look for another short or load that doesn't switch off.

Pat Anderson · Posted: Fri Mar 28, 2008 9:42 am Post subject:

The batteries are both brand new...but yes, I could and probably should do that.

flapbreaker · Posted: Fri Mar 28, 2008 11:49 am Post subject:

I have the BEP cluster you are talking about. Mine came wired incorrectly from the dealer. Took me months to figure out my battery problem. I didn't have one draining like yours but had continual problems with the house battery not charging. The cluster itself comes put together from the factory so the only wiring that's done from the dealer is to put the battery cables and alternator cables in the correct place. Turns out they had the starting battery and house battery cables swithced. Still can't figure out what that did but now I don't have problems. If I were to buy a new switch it probably wouldn't be the BEP. If the house battery gets really low then when you start up your motors it constanly opens the switch and closes the switch as the house battery drags down the starting battery. Doesn't seem ideal to me.

I have the wiring diagram for the cluster in pdf format. If you want a copy I can email it to you. You should be able to find it on their website though.

Wandering Sagebrush · Posted: Fri Mar 28, 2008 12:48 pm Post subject: BEP

Pat, sorry to hear that you are having electrical troubles. That does not sound like any fun, especially if the Wallas is fried.

Right now I feel wiser than a whole tree full of owls for applying the simplicity factor, and just going with a battery switch. That's about all this old one wire electrician can understand.

As Jody said, you can check the amperage drain with a digital multimeter. My suspicion is that the failure is in the cluster, but it could be elsewhere. You may want to disconnect the Wallas to see if that is the cuprit.

Hope this is easily solved!!!

Steve

journey on · Posted: Fri Mar 28, 2008 1:48 pm Post subject:

Pat, Wandering Sagebrush has a very good point: trying to get a simple system to work. At a distance nobody can make an accurate guess on what your problem is.. Getting down to a single main switch which is wired as from the factory, and removing that automatic device, would let you work the problem one step at a time. If you have a random electrical thing that is draining the battery, you can find it that way, and if the batteries stay up with just a switch, then you can figure out it's the automatic thing.

By the way, if your battery gave you the readings you posted in just an afternoon, that's one good draw (5 amps?)

Boris

Sea Wolf · Posted: Fri Mar 28, 2008 2:03 pm Post subject:

I agree with what Steve and Boris have said.

I don't want any wiring on my boat (other than internal circuits in electronic devices) that i don't fully understand and can work on easily myself.

KISS Principle again.

Cheaper to add another battery and manual switch than keep track of a bunch of failure-prone relays that add little annoying enigmas to the system.

That said, I'd get some help, if necessary, to rewire and simplify the system.

Good Luck whatever you do! Wish I lived down the road just a bit to com over and give you a hand!

Joe. Teeth

Pat Anderson · Posted: Fri Mar 28, 2008 4:52 pm Post subject:

Yeah, and that is with no load except the light in the CD - sounds like a short, doesn't it?

Pat Anderson · Posted: Fri Mar 28, 2008 4:56 pm Post subject:

Yeah, I wish you, Bob Austin and a bunch of other folks lived just down the road a bit too! But this forum is just awesome.

I will consider no automatic relay. One question not answered - is there any reason I cannot just wire the start and house batteries in parallel, then I could put a simple on-off switch to the house, which as far as I can see, is the only one I would need. The batteries are both conventional lead-acid but different sizes and amp hours. I could make them both the big honking Walmart Maxx babies if that is necessary...

Wandering Sagebrush

Pat,

My DC education is too far in the past to accurately answer the question about having dissimilar sized batteries in parallel. My belief is that they should be equal in size (and age) so that they charge and discharge equally over time. I suspect that it would not "hurt" to have dissimilar sized, but I do not believe you would get optimum performance.

If there are any EEs on the forum, I would like to hear their comments.

Steve

Wandering Sagebrush · Posted: Fri Mar 28, 2008 5:42 pm Post subject: Redux on Redux

Pat,

I just reread your last post. If you are talking about a temporary arrangement, this should not be an issue. I would not however wire the house and start batteries in parallel as a permanent solution. If while running accessories, you run the batteries down, there went the starting battery. Not a good deal. If you wan to have a couple of house batteries in parallel, no big deal, and my last post stands.

Sorry to have missed your point. Must be my day for speed reeding.

jkidd · Posted: Fri Mar 28, 2008 5:57 pm Post subject:

The switch cluster is a simple device. one switch for the starting battery, one switch for the house battery, and one switch to combine both batteries in parallel. The switches would most likely fail open or closed. I don't think that they would be the source of the drain. However there might be a chance that the ACR could, but it wouldn't be my first choice. The nice thing about the switches is you don't have all the wire to connect them, just some buss bars. The ACR can be disabled by disconnecting the small black wire to it or you put a switch in to turn it on and off at your desire. The nice thing about the ACR is it will keep both batteries charged without me having to remember to flip a switch. It is nice to wakeup in the morning and not have 2 dead batteries.

Larry H · Posted: Fri Mar 28, 2008 5:59 pm Post subject:

Pat,

If your batteries are OK, I would go to the troubleshooting as Jody outlined. Your boat has a current draw that depleted your house battery. A 100 amp-hr battery should provide 50 amp-hrs as the voltage drops from 12.6 to 12.2. If that occurred over 5 hours, that is a current draw of about 10 amps. That is a lot if all switches are off.