Ok, I pulled the ultimate rookie bonehead move. Accidentally replaced my four 6v house batteries with four 12v batteries. 24v...It is a 2003 Monaco LaPalma. I'm hoping there is a bonehead fuse somewhere....I have checked every place I can think of and all fuses are good. Was initially getting too much juice ... slideouts moved very fast. After I discovered issue I connected the rig to just one battery . Things seemed to work for a minute, but as I was trying to start the generator it suddenly stopped cranking and now voltmeter reads zero and nothing works. Hoping for a fuse or circuit breaker somewhere... help

Hook all batteries up together positive to positive, negative to negative so that you get 12 volts total and let them charge overnight. See how things work in the morning.

Time for a complete electrical check up at a good RV repair facility.

When I ran it off just one battery the volt meter read correct (12.5v or so). Then while cranking the generator it initially cranked ok then just stopped entiteky, like a fuse had black wn. Now zero volts on meter.

There are a bunch of what is called parasitic drains that are always connected to the 12V battery system. These are all 12VDC drains so seeing 24V will most likely do them in. Here's hoping their individual fuses protected them. These are control boards, sensors, AM/FM radios main chassis and controls, microwave control boards, air conditioner control boards, any 12v lights that were on, your slide motor was operated - that is probably toast now, etc etc etc... This could be a bunch of money needed to get back to normal...As my drill Sargent would say "Bend over Son"Or one of those oldie Classic County Music Lyrics song "What Was I Thinking" comes to mind...Sure would love to know how this is going to turn out... If it was me that did this I can tell you exactly how it would turn out haha...Hang in there ... Hopefully the 12VDC fuses saved you big timeI would definitely look for the two large value DC FUSES on your 12VDC Distribution Panel that is marked REVERSED POLARITY fuses... They will open up the 12VDC path feeding the 12VDC Distribution Panel. These will be two ATC fuses off to themselfRoy Ken

Pretend like you are fixing this for someone else. Not a joke. The psychology can make a stunning difference in how you rationalize the problem.

Battery disaster | Good Sam Community

MEXICOWANDERER
Explorer
May 31, 2017
Light a few candles.
Not just for the sake of saving money.
What you did could have easily become a danger to you and yours.
Did you "disassociate" from playing the part of "the victim"?
Hobbs1981
Explorer
May 31, 2017
Ok, totally lucked out. Put in 4 new 6v batteries. Everything worked except slide outs. Found I had fried one or two cube relays, now fixed! (Cube relays actually labeled as slide relays. Be nice if everything was labeled!!). So cheap lesson and off to the coast Thursday! Thanks for replies.
Hobbs1981
Explorer
May 30, 2017
Well I "played" with it more. Everything is now working except I think I fried something in the slide out motors because I ran those off the 24v. I'm still happier than I was yesterday. I'll use a breaker bar to move the slides if I have to...
red31
Explorer
May 29, 2017
Hobbs1981 wrote:
Now zero volts on meter.

where? go to batt and measure, then continue further from the battery till ya get zero.
pianotuna
Nomad III
May 29, 2017
Hi,

Follow the positive battery cable. If you are lucky there may be a circuit breaker or fuse usually right in the battery compartment, or near it.

Fuses do not usually protect from over voltage situations.
SoundGuy
Explorer
May 29, 2017
Hobbs1981 wrote:
I'll play with it more tomorrow. I evidently know just enough to be dangerous... any more ideas would be listened to...

Well there's your problem - "playing" with electricity with "just enough to be dangerous", whether 12 vdc or 120 vac, is an invitation to disaster. :E So too is asking for advice here on the forums when your ability to sort out the accuracy of any advice is limited by your own admitted limited knowledge of the subject. Have a qualified tech familiar with RV electrical wiring assess the situation and effect any repair that may be necessary.
RJsfishin
Explorer
May 29, 2017
Voltmeter ?? What voltmeter? That's what you need is a handheld voltmeter, or a 12v test lite. Start at the battery,......nothing ever said that the battery itself did not internally hemorage.
When you have 0 volts in a system, nothing is more simple to trouble shoot.
midnightsadie
Explorer II
May 29, 2017
follow the red battery wire towards the converter ,mine has a fuse there.
Hobbs1981
Explorer
May 29, 2017
Decided the only thing I can fix tonight is my attitude. Beer open.
DrewE
Explorer II
May 29, 2017
Look for a master fuse near the batteries. On my motorhome, at least, and I'd hope on most, there's a big fuse right at the positive line from the battery before the power goes to anything, including the generator starter.

If you're fortunate, maybe only that fuse is blown. If you're really fortunate, maybe it's a circuit breaker that needs to be reset.