1999 Chieftain 35U 12 volt issues

[treimche]

Hello. My first post here is going to be about some 12 volt issues I've started to experience the past few days. I bought this motorhome in May and I've been living in it full time for 3 months now and suddenly my bedroom AC unit has been running constantly, lights have been dim, I sometimes get a "low dc" warning from the fridge, etc. When I connect my 12 volt automotive trickle charger, everything will go back to normal (except for the bedroom AC). Earlier today I pulled the 2 house batteries out, cleaned them up, popped off the caps to inspect the water level, all of the plates were visible in both batteries so I topped off with distilled water.

I have noticed lately too that the little red light below the control panel in the kitchen, which I was told should be lit up red if the solar panel is charging, has been off. It used to be on almost all the time during the day since I'm in Florida and it's very sunny here.

The house batteries are both 12 volt marine deep cycle batteries and they are wired parallel. They have dates scribed on top of them that say May of 2020 so I'm just assuming thats when they were new. I don't see anything connected to the batteries that look like they would be for the solar panel. The only cables connected are the large power and ground cables. There was quite a bit of corrosion on the batteries and on the terminals, so I cleaned them up the best I could. I will get some proper battery cleaner and sealant, along with a new positive jumper wire since one of the ring terminals is looking pretty bad.

I checked the power converter (or is it an inverter?) that's located under the fridge, and it is outputting 12.5 volts. Shouldn't this be charging the house batteries too?

I'm new to RV electrical, but very familiar with 12 volt automotive electrical. Just haven't learned how everything is connected and what should be doing what, and when. I do find it annoying that this thing uses 12 volts to power the controls for the refrigerator and air conditioners. So when the batteries get weak, they all stop working.

Oh yeah, also, after a storm one night, my Powerline EMS stopped working, but that's probably a whole different issue.

Included are a couple of pics. One is the control panel on the wall of the kitchen where you'll notice the round LED below is not lit up red like it should be. The other pic shows the bedroom AC thermostat is set to almost 86 degrees but it kept running and cooled the bedroom to 66 degrees over night (way too cold for me)(the other 39 degree temp is reading from a sensor I have sitting in the fridge to monitor it easily since the fridge seems to fluctuate pretty badly sometimes)

I'm all ears here so if you have any ideas on what's going on and how to fix, I'm open to suggestions. Hoping I don't have to buy 2 new batteries but will if needed.

[Morich]

Shall we start with some basics of the RV electrical to get you an idea? It might be looked at as three seperate but related systems and if we look at them in turn, they may be easier.
One is the pretty standard 12VDC for the chassis. Chassis battery, cables and fuses that run most of the same things we find on cars and trucks. Horn, headlights, wipers and starting? Not too hard to look at that if you know cars?
Fuses/breaers for that are often out under the "hood" like on a truck!

Then there is a second 12VDC coach system to run mostly inside stuff like lights, fans, water pump and the things that a truck doesn't usually have including controls for things like the frig and thermostat!
This second set gets charged in a number of different ways. When we have 110AC power from the cord or generator, you have the converter in the load center that changes ac to dc for running things, with the extra stored in the battery by charging.
I think of the battery as a storage much like a pantry where we store the power till we need it.

Last might be the 110 AC that comes from cord or genset and feeds things like the compressors on air, microwave and outlets. Generally heavier power users than the 12Volt stuff.

Where things get interesting is the way we have all these systems connected at times but not at others! Like when we drive and are not using the generator, there is no AC to charge the batteries or run the microwave?
So unless the RV has an inverter, which older often do not, there is no AC power until we turn on the genset!

The two 12Volt DC can get even more confusing as we want it to do some "special" things for RV. We want the chassis battery disconnected from the coach as a way to keep us from running both down and then we can't get the engine started, so we keep them seperated when stopped.

But we want more?? So there is a dash switch to push, just in case the chassis batttery IS weak. That has different names like boost, aux, etc. but when we are pushing it, there is a solenoid which closes to connect BOTH 12VDC together and we can use it to "jump" a weak start battery!

We have a problem of wanting lots of things and another small point is we want to let the engine alternator put a charge on the coach batteries as we drive! So the solenoid I mentioned also has a second set of wires that make it close when we have the engine running and that feeds power from the engine to BOTH sets of batteries as we drive!

Each system is not difficult to understand but when we add the different ways they can be used, it seems more difficult? So when something goes wrong, we need to first sort it down to which, 110AC, 12VDC chassis, or 12VDC coach? Then we may need to look at things where they are connected to see which is failing.

So when the lights are dim and the frig begins to say low battery, those both sound like the 12VDC coach setup is not giving enough power!
Maybe old batteries or maybe not getting charged right from the converter?

Then the thermostat sounds like a different issue if it lets things get too cold and then maybe get too hot? the thermostast is basicly a switch that is controlled by temp. Sounds like it may have a set of contacts that are sticking and stay closed too long when running until it suddenly pops open! Pulling the cover may let you see a spring gizmo that opens and closes on the older thermostats. For a "quickie" fix, running an emery board across those contacts may clean them up for a while but change is often the real fix?? New digital thermostats are nice if a couple extra bucks are tucked away anywhere!

But one of the main things on RV is keeping the batteries in good shape and that sounds like the first, main real problem to get fixed as it is the "brain" for other things!

Batteries that get dry are often damaged as a hard crust builds up on the lead and it can't react with the water to do it right.
The 12volt runs things as we often do not have 110AC as we move, but that 12VDC should be good if we are plugged in and the converter is charging the batteries. Where the idea falls down is when the batteries don't hold that charge!
If a voltmeter is put on the coach batteries after they have set for a few hours to get stable, they likely show below 12 volts? That would say they are not holding that charge. But if we plug the cord in the converter should show something like 13+ as it tries to charge them. That sudden jump is coming from the converter but DOES NOT mean the battery is full, just that the charge voltage is getting there.

Also if you look at the chassis and coach when not plugged in or running, the two will usually be different voltages. If you then start the engine and all is right, you should see maybe 13+ on both as they are then connected to charge both and let us use all the 12VDC power for the RV that we might want. Inside light may be taking it out but the alternator is putting it in both faster that we use it! Voltage should jump up and down as you rev the engine!

I'm thinking the main problem may get down to needing new coach batteries as they may not be holding a charge??

[treimche]

Originally Posted by Morich

Shall we start with some basics of the RV electrical to get you an idea? It might be looked at as three seperate but related systems and if we look at them in turn, they may be easier.
One is the pretty standard 12VDC for the chassis. Chassis battery, cables and fuses that run most of the same things we find on cars and trucks. Horn, headlights, wipers and starting? Not too hard to look at that if you know cars?
Fuses/breaers for that are often out under the "hood" like on a truck!

Then there is a second 12VDC coach system to run mostly inside stuff like lights, fans, water pump and the things that a truck doesn't usually have including controls for things like the frig and thermostat!
This second set gets charged in a number of different ways. When we have 110AC power from the cord or generator, you have the converter in the load center that changes ac to dc for running things, with the extra stored in the battery by charging.
I think of the battery as a storage much like a pantry where we store the power till we need it.

Last might be the 110 AC that comes from cord or genset and feeds things like the compressors on air, microwave and outlets. Generally heavier power users than the 12Volt stuff.

Where things get interesting is the way we have all these systems connected at times but not at others! Like when we drive and are not using the generator, there is no AC to charge the batteries or run the microwave?
So unless the RV has an inverter, which older often do not, there is no AC power until we turn on the genset!

The two 12Volt DC can get even more confusing as we want it to do some "special" things for RV. We want the chassis battery disconnected from the coach as a way to keep us from running both down and then we can't get the engine started, so we keep them seperated when stopped.

But we want more?? So there is a dash switch to push, just in case the chassis batttery IS weak. That has different names like boost, aux, etc. but when we are pushing it, there is a solenoid which closes to connect BOTH 12VDC together and we can use it to "jump" a weak start battery!

We have a problem of wanting lots of things and another small point is we want to let the engine alternator put a charge on the coach batteries as we drive! So the solenoid I mentioned also has a second set of wires that make it close when we have the engine running and that feeds power from the engine to BOTH sets of batteries as we drive!

Each system is not difficult to understand but when we add the different ways they can be used, it seems more difficult? So when something goes wrong, we need to first sort it down to which, 110AC, 12VDC chassis, or 12VDC coach? Then we may need to look at things where they are connected to see which is failing.

So when the lights are dim and the frig begins to say low battery, those both sound like the 12VDC coach setup is not giving enough power!
Maybe old batteries or maybe not getting charged right from the converter?

Then the thermostat sounds like a different issue if it lets things get too cold and then maybe get too hot? the thermostast is basicly a switch that is controlled by temp. Sounds like it may have a set of contacts that are sticking and stay closed too long when running until it suddenly pops open! Pulling the cover may let you see a spring gizmo that opens and closes on the older thermostats. For a "quickie" fix, running an emery board across those contacts may clean them up for a while but change is often the real fix?? New digital thermostats are nice if a couple extra bucks are tucked away anywhere!

But one of the main things on RV is keeping the batteries in good shape and that sounds like the first, main real problem to get fixed as it is the "brain" for other things!

Batteries that get dry are often damaged as a hard crust builds up on the lead and it can't react with the water to do it right.
The 12volt runs things as we often do not have 110AC as we move, but that 12VDC should be good if we are plugged in and the converter is charging the batteries. Where the idea falls down is when the batteries don't hold that charge!
If a voltmeter is put on the coach batteries after they have set for a few hours to get stable, they likely show below 12 volts? That would say they are not holding that charge. But if we plug the cord in the converter should show something like 13+ as it tries to charge them. That sudden jump is coming from the converter but DOES NOT mean the battery is full, just that the charge voltage is getting there.

Also if you look at the chassis and coach when not plugged in or running, the two will usually be different voltages. If you then start the engine and all is right, you should see maybe 13+ on both as they are then connected to charge both and let us use all the 12VDC power for the RV that we might want. Inside light may be taking it out but the alternator is putting it in both faster that we use it! Voltage should jump up and down as you rev the engine!

I'm thinking the main problem may get down to needing new coach batteries as they may not be holding a charge??

Richard, thank you for one hell of a detailed explanation! This is extremely helpful. I am going to give the coach batteries a few days on the trickle charger, and see what happens after that. I am prepared to just buy 2 new batteries, but if they aren't being charged correctly, then I fear the same thing is going to happen shortly after replacing them. I think tomorrow I will meter the battery voltages and see if the power inverter is charging them. My 12 volt trickle charger is very good, and has a desulfate setting, but I don't think it is designed to handle 2 of these big batteries, as the charger is getting really warm.

[Morich]

Sounds like a plan but with a couple small points.
The converter is what charges and an inverter takes DC power to "make" AC power. Two gizmos that do pretty much opposite! Newer and newer Rv begin to get the inverter as they get into having lots more of the really new battery types for lots more onboard 12VDc so that folks can go way out boondocking and not plug in!

The charger is likely okay even though it may feel hot. the idea is that it will only put out a limited amount of current that it should be designed to do and if we have two batteries it is kind of like filling two buckets? It takes a little longer.

Keeping in mind how long it takes for the voltage we are putting in to get in and around all the chemicals is slow. It can confuse us if we charge and look right aways as that charge may not have got all the way down through the whole battery and just looks good right at the post where we measure it!

One of the most common things we get problems on is the battery systems of one sort or another!

[Ray,IN]

Stop guessing, remove those batteries and have a battery shop load test each one. That will determine if they are good or failing.
For marine batteries, 3 years is about maximum life, installed in an RV. They say deep-cycle but actually are a dual-purpose starting and trolling motor battery.
If you want true deep-cycle batteries buy Renogy AGM batteries, or a Lithium 12V 100A battery.. They are designed for constant use solar off-grid living.

[treimche]

Originally Posted by Morich

Sounds like a plan but with a couple small points.
The converter is what charges and an inverter takes DC power to "make" AC power. Two gizmos that do pretty much opposite! Newer and newer Rv begin to get the inverter as they get into having lots more of the really new battery types for lots more onboard 12VDc so that folks can go way out boondocking and not plug in!

The charger is likely okay even though it may feel hot. the idea is that it will only put out a limited amount of current that it should be designed to do and if we have two batteries it is kind of like filling two buckets? It takes a little longer.

Keeping in mind how long it takes for the voltage we are putting in to get in and around all the chemicals is slow. It can confuse us if we charge and look right aways as that charge may not have got all the way down through the whole battery and just looks good right at the post where we measure it!

One of the most common things we get problems on is the battery systems of one sort or another!

Is it safe to assume the converter should be charging the batteries when I'm plugged into shore power? I'm always plugged in to shore power since I'm at an RV park.

[Morich]

Yes, in that case, if any battery disconnect switch is also on, the ocnverter should be putting out enough power to keep the batteries up to float level around 12.8 to 13, as well as provide any power you would be using. When pllugged in, the converter is putting power onto the wiring and any left over from what we used is supposed to stay in the storage at the batteries.
The idea is that they get full and then that power should be there when we unplug, but if the batteries get to a point they no longer hold that power, we start using thme and they go dead way too soon.

[treimche]

I don't know where the battery disconnect switch is in this RV, and the owners manual doesn't really tell me. I did find a couple of relays under the stairs earlier. When I meter the house battery voltage after sitting for a few hours while we were gone, I'm getting 11.79 volts with a couple of lights on. Earlier I tried unplugging the power converter/charger and plugging it back in, but think I should be seeing a little over 13 volts if it is working properly. It is a Magnetek Series 7400, Model 7455 55amp.

[Morich]

Yes, I might think 13 would be more like what to expect from the converter to the battery as it has to be higher than the voltage at the battery to get any charge done!

But I did some looking at drawings and found a couple points. One is that it did come with a small inverter when built.
This is a parts catalog for your RV and while it is not as nice and slick as what they give us now, it does list the parts and lots of drawings of where and how things come apart.
https://www.winnebago.com/Files/File...9/99wfl35u.pdf About page 35 but the pages aren't numbered?


It only lists the electrical in many cases but it does show there was a 130 watt inverter, some place and some time. Not big enough to watch TV, run a coffee pot, etc but it might work to charge a phone when you did not have Ac power from cord or genset?
You might try looking for small box that is wired in over the cab next to the TV? should have an outlet to plug AC things in?

Then I did look at the 12VDC coach wiring and found some of the drawings for the solenoid that connect the two batteries together at different times like when we are driving or push the dash switch.

First it shows the solenoid that does that but next to it is the battery disconnect relay!
That relay is connected to a switch that should be labled something like batterry disconnect, etc. but they keep changing the names at times. Often near the entry door but some are near the dash or driver.

Click this snip to see better!



When you push the aux or boost switch on the dash or when the enigne is running the power comes down the blue line, through the solenodi coil to a ground wire FM. That makes the contacts close and the chassis battery (RED?) is connected to the green line from the coach batteries. That makes them act like one big battery as long as the switch is held or engine runs!
When you find that switch , notice it doesn't snap and stay like most switches but bounces back as it is a momentary switch that stays connected only as long as we push it!

But then if you know where that solenoid is, there is a relay next to itand they both look like the drawing shows? Find one find the other?

What it means is that there IS a switch somewhere to control this relay. Lots of them are next to the entry door but might be like on the dash or other places? These older drawings were not as good as the new one on computer drawings!

We think you have one but no good info on where to find it!!

[Ray,IN]

Terminology can get confusing. A converter is only that, it converts 120VAC into 12VDC. It requires a built-in or stand-alone battery charger to re-charge batteries. An inverter is just that, it inverts 12VDC into 120VAC, it too requires a built-in battery charger to re-charge batteries and is called an inverter/charger.
Both can have two separate functions in the same container.

[MadMaxWinny]

Originally Posted by treimche

Richard, thank you for one hell of a detailed explanation! This is extremely helpful. I am going to give the coach batteries a few days on the trickle charger, and see what happens after that. I am prepared to just buy 2 new batteries, but if they aren't being charged correctly, then I fear the same thing is going to happen shortly after replacing them. I think tomorrow I will meter the battery voltages and see if the power inverter is charging them. My 12 volt trickle charger is very good, and has a desulfate setting, but I don't think it is designed to handle 2 of these big batteries, as the charger is getting really warm.

Greetings and Welcome!

You have said "trickle" charger a couple of times. I'm sure you mean mutli-stage charger (trickle chargers started to leave the scene 35 years ago). It's important to know the specifications on your 12V components. What size are your two batteries? If they are Group 27, then you can work around a 200 amp-hr number. What brand? As mentioned, not all "deep cycle" batteries are equal. What is the maximum output of your charger? If it's less than 30 amps, it might not recover the batteries from a very low discharge.

[treimche]

Alright finally getting back to this after doing some digging around. On my RV, the battery disconnect relay and battery mode solenoid are in the stairwell behind a cover and a removable panel, very easy to get to.

On the dash there is a "Aux Battery" on/off switch, and a "Aux Start" momentary switch. From my understanding, the Aux Start switch only needs to be used if the chassis battery is dead and needs help starting the engine from the house batteries. I'm not entirely sure what the Aux Battery switch is for, but I think when I flip it to "off" it kills 12v DC power.

When I meter the wires at the contacts of the solenoid and relay in the stairwell, here are the results. (The pics attached are upside down because I was laying on the floor looking down and under the step). On the larger lug on the right side of the Battery Disconnect Relay I'm seeing 12.6v, which is the same voltage as the chassis battery. On the larger lug on the left side of the Battery Disconnect Relay, and both large lugs on the Battery Mode Solenoid, I'm seeing 11.78ish volts which is the same as the house batteries. When flipping either the Aux Battery switch or the Momentary start switch to On, there is no change in voltage from any of the 4 large lugs on the relay/solenoid. I can tell which smaller wire is the trigger from each switch by reading the voltage change on the smaller purple wires, so I can tell there is a 12v signal being sent to the relay and solenoid to switch them, and I can hear/feel them clunking when flipping the switches.

I still have no voltage coming out of the onboard charger, and it doesn't appear the solar panel is charging the batteries. I'm wondering if the charger is just dead, and if there's something not allowing the solar panel to charge the batteries.

[Morich]

Looks like good progress on finding things!
Now I might be able to clear a few questions on what you see and compare it to the drawings we can get online, if you want to get deeper into how we might follow the wiring.
https://www.winnebago.com/Files/File...ram/Wiring.htm

This drawing set and choose your RV, then go to "chassis wiring installation" for this point on the wiring that shows the solenoid and coach battery disconnect. This is a place where they build in trouble because they don't always call things the same!
The dash switch may be Aux for Auxillary battery, boost like to boost the battery? or coach battery disconnect!!!!
But once we find the right switch on the dash that you found, the picture of what you found can match up with their drawings as they do try to show them pretty exact!
Click these to see better!
Your picture:


And their drawing:


I used green to show where the cable from the chassis battery goes to the solenoid and red for the cable from the coach batteries. The real cables are NOT this color but you can spot the big cables for both?
That solenoid is what the small wires from the dash momentary switch moves to close the contacts between chassis and coach batteries! The little wires FM and LR are the ground and battery the work this solenoid and I marked them in blue. FM on this solenoid is actually laid down under the mounting screw/bolt on lots of RV! it can get ground from the dash or from connected to metal here!

If you go to this chart you can find the wire ID on drawings, on the wires, or any place you find the ID and the chart will tell you where that wire comes "from" and goes " to"!
https://www.winnebago.com/Files/File...ical_guide.pdf

Then you have the big cable going between the solenoid and the disconnect relay to the right? Those small wires I marked in blue are what control this relay and make it engage/close or disengage /open, I think LG and lH do that and LJ is one that lights an indicator light, maybe?

This is the really that the AUX dash switch makes move. It moves when you push the momentary switch and then uses a magnet gizmo to stay, either closed or open, depending on which way you moved it last!

When it is closed, battery goes through the contacts and goes out the right side like the orange line!
You see how if this relay is open, the generator starter will not work? Also there is a number 6 black/blk wire that goes up. That is the wire that goes to most of the coach fuses or breakers.
If this relay is open, not much inside works! I don't see it here and LJ may be the one that does it but lots of RV have safety things that stay powered even when the disconnect is open! Co and propane detectors are two that can run the battery down even when we opened the disconnect!

That's one that trips a lot of folks and the battery runs down while stored!

For the voltages and testing, the converter should likely be something you can hear hum, like a battery charger may! But make sure the disconnect relay is set to engage or the charge may not get to the batteries!

Easy way to tell it is engaged is when the inside lights work!

On the two big lugs of the solenoid, though, you should see chassis battery on the left side as these pictures and coach battery on the right.
they usually will be a little different to tell them but when somebody pushes the AUX switch the contacts connect them together and they should show each point the same!

OR they also connect together when the engine starts. That lets us get a little charge back in the coach batteries as we drive. Fun thing to see if you want to test is watch the coach battery side and let somebody start the engine and you should see coach battery jump up and go high/low as the engine speed changes what the alternator is putting out!

One way to find if the converter is putting out and getting to the batteries is to look at the coach voltage with all the switches closed, then plug into power and it should make the coach battery jump higher as the charge voltage gets there! Or start the generator is it's ready to run?

I'll stop and let you chew on things before we both lose our minds. Then IF it doesn't get right, we can chase any converter problems.

Be calm and it all works out someday?

[treimche]

Originally Posted by Morich

Looks like good progress on finding things!
Now I might be able to clear a few questions on what you see and compare it to the drawings we can get online, if you want to get deeper into how we might follow the wiring.
https://www.winnebago.com/Files/File...ram/Wiring.htm

This drawing set and choose your RV, then go to "chassis wiring installation" for this point on the wiring that shows the solenoid and coach battery disconnect. This is a place where they build in trouble because they don't always call things the same!
The dash switch may be Aux for Auxillary battery, boost like to boost the battery? or coach battery disconnect!!!!
But once we find the right switch on the dash that you found, the picture of what you found can match up with their drawings as they do try to show them pretty exact!
Click these to see better!
Your picture:
Attachment 187295

And their drawing:
Attachment 187296

I used green to show where the cable from the chassis battery goes to the solenoid and red for the cable from the coach batteries. The real cables are NOT this color but you can spot the big cables for both?
That solenoid is what the small wires from the dash momentary switch moves to close the contacts between chassis and coach batteries! The little wires FM and LR are the ground and battery the work this solenoid and I marked them in blue. FM on this solenoid is actually laid down under the mounting screw/bolt on lots of RV! it can get ground from the dash or from connected to metal here!

If you go to this chart you can find the wire ID on drawings, on the wires, or any place you find the ID and the chart will tell you where that wire comes "from" and goes " to"!
https://www.winnebago.com/Files/File...ical_guide.pdf

Then you have the big cable going between the solenoid and the disconnect relay to the right? Those small wires I marked in blue are what control this relay and make it engage/close or disengage /open, I think LG and lH do that and LJ is one that lights an indicator light, maybe?

This is the really that the AUX dash switch makes move. It moves when you push the momentary switch and then uses a magnet gizmo to stay, either closed or open, depending on which way you moved it last!

When it is closed, battery goes through the contacts and goes out the right side like the orange line!
You see how if this relay is open, the generator starter will not work? Also there is a number 6 black/blk wire that goes up. That is the wire that goes to most of the coach fuses or breakers.
If this relay is open, not much inside works! I don't see it here and LJ may be the one that does it but lots of RV have safety things that stay powered even when the disconnect is open! Co and propane detectors are two that can run the battery down even when we opened the disconnect!

That's one that trips a lot of folks and the battery runs down while stored!

For the voltages and testing, the converter should likely be something you can hear hum, like a battery charger may! But make sure the disconnect relay is set to engage or the charge may not get to the batteries!

Easy way to tell it is engaged is when the inside lights work!

On the two big lugs of the solenoid, though, you should see chassis battery on the left side as these pictures and coach battery on the right.
they usually will be a little different to tell them but when somebody pushes the AUX switch the contacts connect them together and they should show each point the same!

OR they also connect together when the engine starts. That lets us get a little charge back in the coach batteries as we drive. Fun thing to see if you want to test is watch the coach battery side and let somebody start the engine and you should see coach battery jump up and go high/low as the engine speed changes what the alternator is putting out!

One way to find if the converter is putting out and getting to the batteries is to look at the coach voltage with all the switches closed, then plug into power and it should make the coach battery jump higher as the charge voltage gets there! Or start the generator is it's ready to run?

I'll stop and let you chew on things before we both lose our minds. Then IF it doesn't get right, we can chase any converter problems.

Be calm and it all works out someday?

I highlighted a sentence you wrote, which really helps. My generator will not start. Later I will try flipping the Aux battery switch and starting the generator to see if that works. I'm really starting to lean toward the Battery Disconnect Relay not working correctly. Like maybe it's stuck disconnected, which isn't allowing the house batteries to charge.

[treimche]

On the subject of the converter/charger, I yanked it out last night and pulled the cover off this morning to take a peek inside. The glass fuse is good, but I think the circuit board is toast. You can see how horribly dusty and gross this thing is inside, as it's likely never been cleaned out. Take a close look at the 3rd pic of the resistors and you will see they look like they have been hot, and there is even some small cracks where they enter the board.

[Morich]

Yes, the resisters look bad! Never actually taken a converter out to look and I'm sure they can get lots of dirt in there over the years and that can make it run even hotter than normal.
Whether it is a real problem or just looks bad, no way to tell without see what it puts out when connected to AC from cord or generator!
The generator cranking is easy to know if the disconnect relay is working or not by looking at the lights, vent fans or water pump. If they work when the disconnect relay is closed and stop when you turn it off, the relay is doing all it can!
What I was trying to draw is the short red cable brings the coach battery power from the solenoid to the left side of the relay. Then when it is closed the contacts inside connect the red line to the line I marked yellow to the generator.

I think I see that cable to the gen. is actually red and goes out the front?
There will also be a wire going to fuses on that lug!
This is a different drawing of the same parts that shows more of where the power goes.

Click to see better!


This shows the same chassis (red line) and coach battery (green line) getting to the mode solenoid. There is a black wire going up to a set of fuses that feed lots of the chassis stuff.
The coach power comes in on the green line to the solenoid and there is purple wire that goes direct to a 6 amp fuse. That is the safety stuff that doesn't go through the relay and get cut off!
But most of the power goes to the relay, through it if closed and on to the generator starter or up to two big fuses for the coach stuff.

Red area for chassis fuses, green for coach stuff except the purple safety stuff that doesn't get cut off!

[treimche]

Well now that my batteries have a good charge, when I flip the generator start switch, as soon as I do that, I lose power to the air conditioners and fridge. None of the circuit breakers pop though. So there might be an issue with battery disconnect relay? Since the power to the Generator comes off the stud on this relay?

[treimche]

Just completed another test that might be another answer, or else even more confusion. I started the RV engine and let it idle. Measuring voltage on the chassis battery side of the battery mode solenoid shows 14.5v as it should with the alternator charging the battery. The other lug on the battery mode solenoid, and both lugs on the disconnect relay only show 12.6v. When pushing the momentary (or "boost") switch with the engine running, I get no increase in voltage across any of the other lugs. I'm going to assume at this point I at least need to replace the battery mode solenoid. From what I can tell in the wiring diagrams, that solenoid should be letting voltage through the solenoid when pushing the momentary start switch on the dash, which it is not. I think it should show 14.5v when the engine is running, pushing the momentary start switch, on both sides of the solenoid.

[Morich]

Correct! with either situation, the engine running or pushing the switch the solenoid should connect left and right big lugs together!
But before going for the new solenoid another point should be checked!

The power that signals the solenoid to close comes down from the front dash area on wire LR, goes through the coil inside the solenoid to ground that is provided two different ways. See the small wire FM? It is ground brought in but the wire is also laid down on the mounting screw that holds the solenoid. That makes the ground pretty sure to be there but we don't really know if the battery side (LR) is getting there with the battery to move the solenoid.

This is a big heavy set of contacts in the solenoid and we can usually expect to hear or feel it move. Before changing the solenoid, I would first want to listen or feel while somebody pushes the dash switch. It's easier to hear it when the switch is pushed than with all the noise of the engine starting!

When the coach and chassis side voltages don't come to the same point, it is true that the solenoid is not connecting them together.
But that can happen two ways. It can be moving but the contacts inside are so burned and corroded that they don't make the connection OR if you don't hear it move, the dash signal may not be getting to the solenoid.

This is one where having a helper to push the switch while you are close to the solenoid can be a real help! I don't know where these are and sometimes if the area is quiet, we can hear it thump but if there is noise around the RV, it is better to stand close or feel of it.

If you want to do it alone and have a meter to read voltage on that small wire LR, it should have no voltage and then when you start the engine there should be 12 volts or more on the small wire.

Not trying to flood you with too much but there is a third way to test the solenoid being good.
It needs 12 volts or more on the center lug (LR) to make it close the contacts. If you have a meter connected on the right big lug and it shows 12 something, you can put 12 volts on that small wire by using some small wire from the left big lug to the center!

Working by yourself can get tricky but if 12 volts on that center lug is what makes this work, steal some from the left where you are seeing chassis battery! Kind of jump starting the solenoid instead of a car?? Expect a little bit of spark but not like connecting a battery , etc.

If it jumps up and connects the two when you put battery on that wire but not when the dash switch is pushed and supposed to put battery on, the solenoid is okay but not getting the signal from the dash!

[treimche]

I did verify that the small purple wire from the dash switch was triggering the battery mode solenoid, therefore the solenoid was bad. I ran to Napa and grabbed a new ST80 solenoid courtesy of this thread https://www.winnieowners.com/forums/...d-65534-3.html and installed it.

Upon installation I had no 12 volt power to anything in the RV. Checked all fuses and breakers and everything was fine. Started the engine and checked voltage across all 4 of the large lugs on both solenoids, and there was indeed over 14 volts while running. With the RV engine running, all of the 12v powered items came back on (fridge and ac are the main concerns). Turned the RV off and lost all 12v power again. Checked fuses and breakers, nothing wrong. Started the engine again, fridge and ac came back on shortly after. Turned engine off, everything stayed on. Went back to the display panel and hit the "level test" switch, and all 12v power was killed again. Very confusing. Still no blown fuses or tripped breakers. Finally started fiddling with the 2 switches on the dash and figured out that flipping the the Aux start switch on a few times gave 12v power to everything.

Everything has stayed on since Saturday evening when I went through all of this. I'm wondering if the battery disconnect relay was stuck open, or if maybe it is sticky and should also be replaced for peace of mind.

Regardless, we are making progress here and it's feeling good.