2019 Forza 34T outlets and fridge lose AC power on shore power

[Kjhall]

We've only had our Forza for a few months, we had extensive mods done to it for accessibility unrelated to this issue. On our first VERY local overnight trip we hooked up to shore power at the campsite. My Watchdog showed 117V on both legs, all good. Everything was fine for 24 hours till I turned on the water heater, and then the AC to the outlets and fridge dropped. The roof air conditioners kept working though. I checked the breakers, all fine. I disconnected the shore power and the A/C quit, so I know we were getting power through from there. Turned on the generator, didn't help, still no fridge, no outlets. The display in the hallway indicated low voltage, but if we were plugged in, why would that happen? I needed my CPAP overnight, so we left early and went home. When we got back to the storage lot, I tested again, and the outlets and fridge were back on, apparently whatever had been blocking them was resolved by a half hour on the road. Looking over what I could see, the only thing odd was there's a black-box surge protector in one of the bays that had a power cord next to a 110V outlet, and it wasn't plugged in. I took the rig back to the shop and they went over it, and couldn't find anything wrong. I picked it up, and now that cord is plugged in, they told me it should be.

So here's the question: Do the fridge and outlets run off batteries all the time, even when shore power is connected? Could the unplugged surge protector have been preventing the batteries from recharging while on shore power? The manual isn't clear on the exact flow of current in the various situations. I'm planning another local test run soon, but it would be nice to have some idea how this is supposed to be working.

 

[Morich]

Yes, Alway a good plan to make a try at understanding what might have happened when we get a new /different RV!
One of the big things is that most RV ARE NOT all like the next one! So we need to do the study to find what WE have and in your specific RV year and model there were THREE different build dates to add to the confusion. So maybe a first stop is to sort out which build you have?
There should be a label somewhere close to the driver's left side, perhaps?

This label or maybe a title or paperwork to tell which SERIAL NUMBER is the 7th digit? This is the way Winn sorts out which build date as 1 for early, 2 or 3 for later in the year. That will let us go to the drawings with more confidence that we are looking the right place!
But you may also want to go direct to those drawings to get some idea of how the power should flow in the RV. For this, choose the correct RV, then 110 AC drawings.

Wiring Diagrams

I have a theory to start and I think it may be the same on all those build dates but uncertain until checked.
I think this will do for a starter on what I see may be happening. This doesn't show the added protection but may explain what I feel may need checked.

At left I marked the path from the cord into and through the transfer switch as green. I also marked from the generator in the same way as blue. Idea is that both the cord or the generator should be giving you good AC power at a good level. But things can fall short. When we don't get good voltage from an outlet, it "might " be a fault in the outlet or cord? When we try to use the generator, it can also be bad.
But when you got bad results from both, it tends to say they were good and we have a problem further into the RV???
See how both the green and blue lines should send power up and out on the red lines? If we say both are good but come out bad at the top where we send it on tothe RV, logic tends to say we might have a problem getting power through this set of contacts and connections in the transfer switch! A bit of guessing and such but this transfer switch has a problem at times which you may want to check.
No quarantee but maybe a place to check?
It has kind of a tough job as we drive and bounce things like the wires every time we hit a bump. One thing that can happen is this soft copper wire get jerked on enough that it eventually can get flattened or a bit loose where the screws hold the wires!
Just a theory but if you have a screw connection beginning to get loose, now would be a good time to go in this switch and tighten those screws!
What we may find happen if given enough time, the wires get loose enough to not make good tight contact and then we begin to get a little arc welder going to burn the contacts off!!
Since you seem to be saying it looked a bit bad and then it seemed to change, maybe there is a loose wire that is almost coming loose?
I tend to think the surge protector is not going to be the real issue as the generator doesn't work through it, only the cord if I understand what you mention. My thoughis that if both cord and genrator are not acting right, we need to look at the path both take and the transfer switch seem suspect!
Carefull if going in to look at this as you want to be sure the cord is not going to get plugged in nor the generator start!
Not a hard job to tighten all those screws, just make sure it all stays dead and NOT you!!

 

[Kjhall]

Thanks, that's good info. The 7th digit is 1, it's an early build. I had gone to Winnebago with the VIN even before I bought the rig to get the build sheet. The tech tells me they couldn't find anything wrong, so your theory about a loose connection might be correct. Driving home might have jostled it back to normal. Problem is, if it happens again, the dealer is charging me $200 each time as a "diagnostic fee", so at this point unless something fails hard, I'm not taking it back to them. The campsite had an on-site tech who had offered to help, but by the time this popped up it was too late to get him involved. The house batteries are only a year old, so unlikely there's a problem there. My theory was that the outlets and fridge were running off the batteries with the shore power going through the surge protector and charger to keep the batteries charged, but with the surge protector unplugged, the batteries weren't actually charging and eventually ran down. That doesn't seem like a good design, but it fit the symptom.

 

[Morich]

Yes, understand doing things when it looks right. A bit more on how the wiring is expected to be. This assumes no changes but I would not expect them on our Newer RV.
Once changes are made it throws the OEM plan out!
But the idea is that you plug the cord or start the genertator and the transfer switch "tranfers" the load to the one it think is working. From there power goes to the AC load center on two 110 Volt legs to two main breakers to feed different smaller breakers. One main feeds the subbreaker that goes to the inverter. Other small breakers feed other things direct. The AC gets tot he inverter and it can pass it on, something like a switch. OR if no AC comes in, there is a connection to battery and the switch can make AC from the DC that it passes on.

So in from transfer to one of the main breakers to feed smaller breaker to inverter.
That inverter chooses which feed to pass on to inverter main panel breaker. It passes commercial AC or AC "made' from battery on to main inverter breaker and also smaller.
Much of your AC users do get power through the inverter as I had to cut off a fair amount at bottom. Not the air and not the parts below this on left! So if you have no inverter on OR passing through, lots of stuff will die, like frig and microwave.and all those outlets below!
There is likely to be a place to turn the inverter off and we usually don't want it on and drawing battery UNTIL we have no AC source and DO want to use battery to keep the inverter things working.
That can be confusing enough but we also havetimes when we might see the frig or furnace stop working if we lose the 12VDc that runs the controls on those! Different grig may have different controls but the furnace and air conditioner almost always need bothe 12VDc for controls as well as 110AC to run!
Hate to flood your mind with too much stuff but it is like driving. You might get to Miami without thinking too hard but if you want to go to Chicago, you have to get the map and study a lot more!
I guess we are lucky it works most of the time!
AND I do fully agree with not wanting to pay that diagnostic fee. Too many times it feels like they really never give it enough thought and dig into things that may just be a loose connection bouncing around! UGH!
I think I may have a doctor doing that ! OR MAYBE? I may have a screw loose and he can't find it?

 

[Kjhall]

I did notice that the inverter didn't seem to want to work while the problem was happening, and there was a "low voltage" indication. What I guess I'll have to do is see if it happens again and then try to get the on-site tech to look into it, maybe take some voltage readings on the outlets and pictures of what the little display is showing. I checked all the breakers while it was broken, didn't reset any, none were tripped. It just sort of magically started working again after the drive. I worked for an electrician in my younger days, I'm familiar with the basics here, the inverter, generator, charger, etc. It's just the way the whole thing is put together that isn't well documented. Thanks for the info.

 

[Morich]

That sounds like a start but there is one point that always makes me a bit nervous when dealing with any form of monitor panel to get readings on an RV. Corrosion is one of the big ones we have more of than in stick built places. Corrosion due to more temperature changes and outside combined with things shaking around to try to loosen any connection we make are a bad combo. So I tend to like to always keep a small digital meter on hand as the tool that gets the most use! I never fully trust the monitors as they can be suffering from poor connections that make me wonder if they are telling me the truth or leading me down the path?

 

[Kjhall]

I keep a DVM in the rig, but didn't use it that night. Next time, if it happens again, but crawling around the bays is hard on my knees. I went this morning to collect a couple of things I had left in the rig and noticed the display said the house batteries were down to 11.5V, which seemed strange since everything was turned off and the batteries are only a year old. Does that sound normal?

 

[Morich]

Yes, sounds possible and there is a dirty little secret involved! When we turn the battery disconnect switch off, it actually turns MOST of the drains off but it DOES leave safety items still connected! Verify this by looking for a green LED on smoke or propane detectors. They do not want to be blamed if you came back to find the RV full of propane to blow up!
The 11.5 sounds like it dropped quicker than it should, however?? Normally it takes a week or two to go low.
We always have to keep in mind that one way we might get a low voltage reading on any remote reading is if the connections from the battery to that remote point are not totally good and clean. Don't want to sound paranoid but getting a meter reading right on the battery posts is more reliable. Then while there, put the probes on the cable clamp to see if you get the same reading. Right at the battery where we may have had acid and fumes is a really good place for corrosion to start!
But for the battery disconnect, it would be more correct to call it a partly battery disconnect! To make matters more difficult, that switch and relay will cut much of the drains but not all, while it totally disconnects the batteries from charging!
What this can lead to is newer users can think they have disconnected ALL the drains but they want to make sure the battery stays charged so they leave the RV plugged in and think that lets the converter keep things good. WRONG!
What they have done is assured it will run down, slower due to much of the load disconnected but then in the spring they find out the charging may have been left powered but not reaching the batteries! Let that happen over three months of qwinter andit is almost cretain to kill a set of batteries!

 

[Kjhall]

Looks like it's resolved, but not sure how. Some more fiddling determined that the batteries weren't charged fully and if the shore batteries go below 12.2 volts, the inverter and AC power to the outlets and appliances shuts off even on shore power. CW didn't find anything wrong but they did determine that the built-in surge protector should have been plugged in and it wasn't, so I suspect the batteries were slowly draining even on shore power, and when the voltage dropped below 12.2, it all shut down. With the protector plugged in we did another test weekend, and the display had somewhat different indications. The batteries charged up and the charger went to "float", which I had never seen before. After that it looked like the batteries were charging normally, and we had no trouble. Very odd. I've taken to turning off the third cutoff near the battery compartment, but I'm not sure if that cuts the shore or chassis batteries. The electric stairs still work even with the switches all off.