House Battery Switch

[Freestyle]

I am a long way from home with a dead starboard battery that serves the house side. It powers the fresh water pump and heads so I can't use them even in port, and much worse, at anchor or underway. It also powers the electronics but they seem to work once the alternator picks up voltage

Does anyone know how to switch the house service to the other battery?

I have two barrell selectors next to each engine. They are both on "Both" as opposed to 1, 2, and off which are the other choices. The parallel switch on the dash allows me to start the starboard using the port.

Thanks

Bruce

 

[Genesis]

Be very careful with this.

It sounds like you have a bad selector switch in addition to a dead battery - or perhaps, you have a perfectly ok battery but a bad switch or bad wiring. My advise would be to first disconnect the dead battery (it will drain the good one!) and then see if you can find a selector switch position combination that powers everything off the good one.

 

[Nonchalant1]

I'll answer your question in the last paragraph, but first, check those big "shotgun shell" fuses with a continuity tester, or even a wire, a flashlight battery and a flashlight bulb. They're impossible to tell if they're OK by looking at them. If a fuse is good, it'll conduct current. If it's blown, it won't. A bad fuse will prevent a good charger or good alternator from charging a good battery bank. I'm betting that that's your problem and you can just replace them (Ace hardware) and go.

If not, then I'd agree that you should first disconnect the switches. Something is wrong there and you don't want to start a fire. If you can do without power while you investigate, turn the switches to off and then disconnect both battery banks by removing all cables from the positive terminal.

Then check the "bad" battery bank. If you have a voltage meter, or the dash meter is OK, check the voltage compared to the nominal volts. A 32 volt battery bank will put out over 33 volts when charged and will measure under 32 volts when discharged. If you have a battery hygrometer, measure the specific gravity of each cell. If they're all roughly equal, the battery is OK, even if discharged. The hygrometer will show what specific gravity measure is charged (i.e.1275) vs. discharged also.

If the batteries are OK, then follow the cables from the positive terminal on the house bank to both switches. You may have a loose or melted lug or terminal or bad cable somewhere. The hard part is just following the cables. If something is bad, it's usually easy to see. Feel the connections for loose terminals too.

Then, if you're comfortable with electrical work:

If they're all fine, open the switches and see if they look OK. If you have them both set to "both" then both banks should be paralleled mechanically, but you said the parallel switch allows you to parallel them and it works to start the starboard engine, so thats strange. If it all looks fine and clean and the fuses, cables and terminal connections were OK, I'd still worry about the switches. I'm not sure I'd hook them back up if they can be bypassed.

Last, to get you home but probably not ABYC standards, it is possible to add a manual parallel switch, but it can be tricky to use. You can go to NAPA and get 2 short cables big enough (like 00 size for a 32V system) to carry house loads, but not starting loads, and with terminal lugs the same size as the parallel switch soleoid terminals. Then get a 75 amp (or more) automotive push-pull power switch (75 amps @12V = 28 amps @32V). Use the 2 cables with the power switch in the middle to make a "switched jumper" for the parallel solenoid for your battery banks. Be careful - these wires and terminals can't touch any other wires or ground...protect them well. Turn the switch on to use both banks for everything, and to charge the bad bank when running or charging, but NEVER try starting with the manual parallel switch turned on because it can't handle starting current loads. Also remember that if they're paralleled, they'll equalize over time so the good bank will charge the low bank until they're both the same charge state. That can be good or bad based on charge conditions.

If you're not comfortable doing this type of work, stop at a good marina.

Good luck,

Doug Shuman

 

[Genesis]

Unlikely to be the "shotgun" fuses since he can parallel and have it work.

The ANL fuses in my panel are all downstream of the parallel solenoid.

 

[DickB]

This one has me stumped but I'd appreciate knowing what you find when fixed. I don't understand how the batteries and sw could fail at the same time. I don't see how they're related (unless the switch is shorted but I think there would be some other obvious problems).

You could check continuity through the switch recognizing that it still may not carry any current. If the switch is suspect, you could remove the lead from the output side and reconnect directly to the lead coming from the battery. That simply "wires" around the switch. But that still leaves the system connected to a dead battery which apparently won't charge even when running the alternator. Leads me to believe it's just a battery problem.

If you're certain that the sw is ok, you could consider disconnecting the battery from the system, and reconnecting the leads from it to your good battery. Don't know how far apart your battery banks are. That would also give you another check on the sw. But then you no longer have a dedicated start battery.

Interesting problem.

Dick

 

[Nonchalant1]

Unlikely to be the "shotgun" fuses since he can parallel and have it work.

The ANL fuses in my panel are all downstream of the parallel solenoid.

Karl,

Maybe different setups for different boats and years, and it's one REALLY EASY thing to check and fix. My comments are accurate for my boat, but I recognize he has a completely different boat than either of us. My original big fuses are at the original battery on-off switches. If they go, I can still use the house bank until it dies and I can still start both with a parallel switch, but the bank won't charge from the charger or alternator. However, I don't have the "1 - 2 - both" type switch either.

Bruce may have something completely different than either of us, but since it would work on my boat, I thought it was worth a shot on his. Sometimes if enough of us give ideas that work on our boats, one of them will hit the target for his.

Thanks,

Doug

 

[Genesis]

Yep...

My alternators are on separate fuses - if they blow due to a short other "event" then the alternator doesn't charge, but the rest of the electrical system is ok.

There should be schematics on the boat (unless they've been lost!) - mine had 'em, and I considered that to be incredibly valuable data to have, as it gave me a baseline for how things should be. Of course things had been added and changed over the years, but knowing how the factory did it originally CERTAINLY helps.

 

[Traveler 45C]

Bruce, it seems to me that if you just follow your wires and carefully make a diagram it should be obvious to you how to make the switch to the other bank. The system will look more logical to you on paper.

 

[Freestyle]

Thank you for your thoughts and suggestions. Here is what I figured out.

I gave the generator a 12 hour rest and lived on the inverter for a while. I always turn off the battery charger when on the inverter so that it doesn't pull too much current. During this period on the inverter I had a lot of 12v stuff running. Thus explaining the starboard battery running all the way down.

When I turned on the generator I also turned on the battery charger. The battery charger charges both battey banks. According to its manual, it shuts down if it is hooked to a really low battery that has a load applied to it. So that is why running the generator did not put any juice in the house battery.

Fortunately a three hour cruise let the alternators fill up the starboard battery bank and I have had no trouble since.

I should probably either get a better battery charger or at least learn to operate the system within the limits of its capacity.

I also think that if a load kills one battery bank the dumbest thing to do is put that load on my only remaining good battery bank because the real reason to have batteries is to start engines--not to play loud music.

Bruce

 

[Nonchalant1]

Bruce,

Glad you figured it out. Most inverters also shut down when the bank's down to 50% remaining, but it sounds like yours doesn't. Also, since you have your switches set to "both" you can ran down both banks to where they wouldn't start an engine. You may want to set one to "1" and the other to "2".

So you have a combination of electronics that requires more watching, but once you know, you can handle it. They make some nifty battery bank condition meters you could easily install if you want to. I just watch my helm voltage gauges as a charge level indicators.

Doug