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Battery Disconnect Switch

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I turned off my battery disconnect switches when I was out of town for a week. Now the chassis switch works but the coach switch will not turn on to power the 12-volt circuits. I can find no circuitbreakers of fuses blown. All inverters and 120-volt circuits seem fine.

Any ideas where to start looking?

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Donald,

In our coach the battery disconnect switch activates a solenoid which switches the battery circuit on and off. You haven't indicated the make, model and year of your coach so this may or may not apply to your situation. The solenoid is subject to failure and if it does, the switch will do nothing. If we know the information about your coach, someone may be able to direct you where to look for the solenoid.

A second possibility is that the house batteries are dead. Yes, you shut off the batteries with the disconnect switch but there are a number of other loads that are not disconnected by the battery shut off switch in most coaches. Some of these parasitic loads include the smoke/carbon monoxide/propane detectors, various electronic indicators and other things the manufacturer may have wired outside the battery cutoff circuit. They are small loads but may in a weeks time completely discharge the battery.

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Donald,

In our coach the battery disconnect switch activates a solenoid which switches the battery circuit on and off. You haven't indicated the make, model and year of your coach so this may or may not apply to your situation. The solenoid is subject to failure and if it does, the switch will do nothing. If we know the information about your coach, someone may be able to direct you where to look for the solenoid.

A second possibility is that the house batteries are dead. Yes, you shut off the batteries with the disconnect switch but there are a number of other loads that are not disconnected by the battery shut off switch in most coaches. Some of these parasitic loads include the smoke/carbon monoxide/propane detectors, various electronic indicators and other things the manufacturer may have wired outside the battery cutoff circuit. They are small loads but may in a weeks time completely discharge the battery.

What types of issues might cause the solenoid to fail?

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Donald,

In our coach the battery disconnect switch activates a solenoid which switches the battery circuit on and off. You haven't indicated the make, model and year of your coach so this may or may not apply to your situation. The solenoid is subject to failure and if it does, the switch will do nothing. If we know the information about your coach, someone may be able to direct you where to look for the solenoid.

A second possibility is that the house batteries are dead. Yes, you shut off the batteries with the disconnect switch but there are a number of other loads that are not disconnected by the battery shut off switch in most coaches. Some of these parasitic loads include the smoke/carbon monoxide/propane detectors, various electronic indicators and other things the manufacturer may have wired outside the battery cutoff circuit. They are small loads but may in a weeks time completely discharge the battery.

Tom, We too have a Monaco product, a 2007 HR Endeavor and just recently experienced the battery disconnect switch problems. The switch has been cutting out requiring a reset by turning switch back on. Battery seems to be fully charged. On two occasions, the coach was plugged into shore power with battery tender connected. If the solenoid is subject to failure, is this the likely problem or perhaps an indication of another problem? Is the solenoid easily replaced?

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I vote for the solonoid. In my coach (Alfa) it is located under the driver's side dash and it has also failed once. Dead batteries are possible, but one week of "parsitic" load is probably not enough to drain them. Be that as it may, it's a good idea to check to see if any of those are on (check the LED lights) after you use the disconnect switch. If they are, most of are easily unscrewed from the wall. Then you can disconnect the ground wire of each to kill the entire unit.

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In our Windsor, the battery cut-off switch by the entry door connects to a solenoid in the electrical compartment under the drivers position on the outside of the coach. It is easily identified by the large 12V cables that connect. In reality, many people simply bypass this solenoid by connecting the two 12V leads together with a bridge cable if necessary. Then the switch connection (a small wire) is capped off. This makes the switch inoperable but takes care of the solenoid. Monaco has another battery cut-off in the rear of the coach. The front switch is commonly called the salesman's switch. Located at the door so a salesman can flip the switch as they enter the coach to show it to a prospective customers. The rear cut-off switch is the primary one and would still function without the solenoid. The rear switch and the solenoid are installed in a serial circuit. If either is off, the circuit is off. Bypassing the solenoid makes the rear switch the only one on the circuit. The rear switch is a positive switch, no solenoid. You are in control.

If you want to replace the solenoid, it is easily done. I am on my third one and have finally taken it out of the circuit but I'm full time and don't need to shut off the battery - haven't done it in 9 years! Well, I did when I replaced a set of batteries but as explained above, I used the switch in the rear electrical compartment. My solenoid is in storage. I'll put it back in place when I sell this coach.

As to issues that make a solenoid fail, there are contacts that will get corroded. It is an electronically (magnetically) operated switch and the magnet can fail to operate the switch. If it is intermittent, this is what is likely happening.

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Once you find the solenoid, check with a volt meter to find the 12 plus line. Then apply a jumper between that 12 volt line and the control terminal. If the solenoid operates then the switch is bad. If it doesn't then the solenoid is bad. Just a way to isolate the problem.

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Once you find the solenoid, check with a volt meter to find the 12 plus line. Then apply a jumper between that 12 volt line and the control terminal. If the solenoid operates then the switch is bad. If it doesn't then the solenoid is bad. Just a way to isolate the problem.

To amplify just a little, all solenoids have two large lugs-- one always hot, the other hot when the solenoid is energized.

Some solenoids have two small wires, a SIGNAL WIRE and a GROUND.

Some solenoids have only one small wire, the SIGNAL WIRE with the body of the solenoid serving as the ground.

Jumping from the "always hot" large lug to the small SIGNAL WIRE terminal is great. But do NOT jump to the small ground terminal if your solenoid has two small wires. That would be a dead short to ground-- lots of smoke and heat!

Brett

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Guest Wayne77590

Wow! And if that smoke escapes, you will have to send it back to China to be repacked with smoke. They make the smoke by dancing in the street.

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Wow! And if that smoke escapes, you will have to send it back to China to be repacked with smoke. They make the smoke by dancing in the street.

O'boy........Good Grief....

Good one Wayne..............

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Those battery disconnects are more trouble than they are worth. They really give you a false sense of security. They either wouldn't engage and make connection and come on, or would connect and the internal connection wouldn't be solid and I would have dim lights etc. But of course the worse part is if you need to use your rig and you push the rocker switches and nothing happens. This is seriously aggravating. So I took some heavy cable and just wired around them so that the system is always on. If I need to disconnect the coach and chassis when in storage mode, I just disconnect the negative battery cables, which also gives me a chance to inspect the battery for water and corrosion at the cables.

The disconnects on an rv are a bad idea I think, because like some else said, they corrode on the inside and you can't tell if they are working properly and conducting power at the correct amperage. So even if they seem to be working properly they may have internal resistance because of corrosion. I have taken them apart and believe me they do corrode. This means that when they are in the on mode and connecting the batteries to either the coach or chassis the batteries may not be getting the full charge they need and also not providing the full power that is needed for the coach and the chassis, which could result in failures of some circuits and possibly even fry a motor or circuit board. I know that sounds a little extreme but battery disconnects are definitely a weak link in your electrical system. I'd rather live without them than worry about them!!!

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Great responses. Thanks particularly to Tom and Brett. The solenoid was right where Tom said it would be and yes it was dead. I continue to be impressed with the amount of helpful information that is exchanged across the FMCA blog. I for one, did not know you could get the smoke put back in electronic equipment after you accidentially released it. :rolleyes:

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The battery disconnect switch. Will I ever need to use it, I hope not. Yes, I know where it is and how to use it. When the day comes that I need it, it will be a sad day for this motorhomer. I don't plan on stopping long enough to need the 'Battery Disconnect Switch'. Maybe the guys in the shop may use it for some reason but, not me. When the time comes for the Good Lord to call me to rest, I will use the switch but not before. Happy travels.

Cal206

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ON MY 08 MONACO PRODUCT THE ELECTRICALLY ACTUATED MECHANICALLY HELD (DRAWS POWER ONLY TO LATCH IN THE ON POSITION)CONTACTOR IS LOCATED IN THE FRONT OUTSIDE DRIVERS SIDE POWER PANEL. FAILURE WAS CAUSED BY CONDENSATION.

ONCE I SEALED ALL THE CABLE OPENINGS AND CRACKS WITH A FULL CAN OF FOAM SEALER THAT WAS NEVER DONE AT THE FACTORY THE FAILURES STOPPED.

A NEW CONTACTOR CAN BE OBTAINED AT MEGARVPARTS.COM FOR $50.00---exact replacement.

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The above postings may have diagnosed my problem.  

I have no 12v system power; i.e., coach lights, A/C thermostats, etc.--on both shore power and generator--unless I hold the entry door electrical panel 12V disconnect switch down.  If I hold the switch down, then the 12V system functions normally--I have lights, I can operate the A/C thermostat, etc.

Does this sound like the solenoid?

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1 hour ago, rpbuttery said:

The above postings may have diagnosed my problem.  

I have no 12v system power; i.e., coach lights, A/C thermostats, etc.--on both shore power and generator--unless I hold the entry door electrical panel 12V disconnect switch down.  If I hold the switch down, then the 12V system functions normally--I have lights, I can operate the A/C thermostat, etc.

Does this sound like the solenoid?

There are two kinds of disconnect switches:

Mechanical-- in which case the switch is bad or you have a loose connection at the switch

Electrical-- a switch used to open/close a solenoid.  In this case the switch by the door sends a signal to the signal terminal of the solenoid.  The switch could be installed on either the positive or ground side of the solenoid small terminals.

In your case, since "working" the switch causes it to work/now work, I would start with the switch (again assuming you have the electrical type).

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On 5/8/2016 at 10:34 AM, SherryCasteen said:

Can anyone tell me where the ignition solonoid is located on a 2002 Monaco Windsor thanks

There are a series of ignition relays in the front electrical panel which is located below the drivers left foot and accessed through the door on the outside of the coach.  The starter solenoid is located on the starter itself.  I'm not an expert but in reviewing 67 pages of electrical diagrams for the Windsor, I can find no reference to an ignition solenoid. 

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Sherry  I believe you will be looking for a relay more so than a solenoid.  Check the definition below and you may find that the only solenoid on the coach is on the starter.  All the rest are relays even the big round shiny ones,  Like I said before you could have a circuit breaker tripped by the batteries.  A test light is you friend in when checking for a dead circuit.  

What are the differences between a relay and solenoid? - Quora

When energized, both get magnetized and give some mechanical movement. In a relay, this mechanical movement is used to turn on/off a switch contacts while in a solenoid, the mechanical movement is used for some other work like opening / closing a door etc.

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On ‎5‎/‎9‎/‎2016 at 8:14 AM, rpbuttery said:

The above postings may have diagnosed my problem.  

I have no 12v system power; i.e., coach lights, A/C thermostats, etc.--on both shore power and generator--unless I hold the entry door electrical panel 12V disconnect switch down.  If I hold the switch down, then the 12V system functions normally--I have lights, I can operate the A/C thermostat, etc.

Does this sound like the solenoid?

To me, this sounds like your switch at the door has gone bad.  Same exact thing happened to us.....everything would work if I held the switch down.  Went to RV supply store, bought a new switch, and all worked fine.  I carry a spare now.

Blake

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Got a message from Sherry that the problem turned out to be the ignition relay.  Glad that it is fixed and we did not lead astray.   

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Ok I am new to FMCA. Been a RV owner of and on for 10 years or so.  Ok. Just purchased a 2006 coachman encore 40 diesel. Got home from a trip tonight.  Dropped jacks put slides out and plugged up to 110 as usual (just to keep batteries charged).  During our trip the water pump went out.  Turned it on.  Did not work.  Now the 12 v systems in the coach do not work.  Slides will not work. All 120 volt appliances work but no 12 v. The ref doesn’t power up at all on lp or 120.    There is a battery disconnect in the front panel   When I switch it it does not do anything  no sounds just pushes down and rocks back.   I have attached a photo. It is the bottom switch.  I am puzzled.   Feels like something is switched off.  12 v is completely dead.  The coach batteries are brand new.   Does anyone have any ideas?

CF7BD5B9-44B5-4687-A9B9-69C9447AB705.jpeg

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Wow, all this talk about solenoids and remote switches makes me glad that our system is so simple. Rotate the switch next to the chassis batteries from on to off and the battery is disconnected. Same for the switch next to the house batteries.

Even if our coach was born in this century, one of the first things I'd install would be a truly mechanical battery disconnect switch. I'd use it every time I parked for more than a day or two. A really nice Blue Sea switch can be ordered for less than $100 and will outlast my bus. I would avoid anything generic or made overseas unless it was a known high-quality item.

The automated systems can be left in place - the manual switch is my mind is in place to act as a fail-safe to avoid any unknown phantom loads draining batteries.Best placed as close to the batteries as possible.

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