The "Meg" Build

[Lt.Dan]

So I didn't need to remove the Grid Input from the transfer switch? ?

Whats the next step?

While I'm on my trip, we are going to be boondocking for 4 days, and away from everything here at home, I'm going to check for voltage between the rig and earth again and see if there is a difference. Would that prove its something here? Like the solar panels on the container?

I might just replace all the wiring anyways and see where that gets me, even though it's probably $400 in PV wire...

 

[FilterGuy]

o I didn't need to remove the Grid Input from the transfer switch?

Correct.... Sorry.

 

[Lt.Dan]

Correct.... Sorry.

No worries haha.

 

[12VoltInstalls]

I'm going to check for voltage between the rig and earth again and see if there is a difference. Would that prove its something here? Like the solar panels on the container?

Sorta. Or yes. Or maybe.
The container is part of it circuit-wise but the other things revealed tend to seem like an onboard issue and the container is merely an innocent victim.

But Definitely Test!

 

[Lt.Dan]

Alright, im back from my trip, and while there, I confirmed there was less than 1V AC from earth to trailer while there. I came home, and again measured just a tad over 100V AC from earth to trailer.

What would be my next test? Is the array on the container the only thing left to look at?

 

[K8MEJ]

Alright, im back from my trip, and while there, I confirmed there was less than 1V AC from earth to trailer while there. I came home, and again measured just a tad over 100V AC from earth to trailer.

What would be my next test? Is the array on the container the only thing left to look at?

Can you elaborate? Were you plugged in when you measured the 1v on your trip? Were you plugged in to shore power when you returned home? Did you connect to the cargo container grid?

 

[Lt.Dan]

I went boondocking in the middle of the desert, nothing around for miles, no power and no cell service even. Measured less than 1VAC.

I came home, parked in my usual spot and plugged in the MC4 connectors to the panels on the shipping containers, and read just over 100VAC from earth to trailer.

Then I removed the Neutral-ground bond from the RV distribution panel (that I installed just for the trip) and plugged back into the grid. Almost 0VAC from earth to trailer.

 

[FilterGuy]

Alright, im back from my trip, and while there, I confirmed there was less than 1V AC from earth to trailer while there. I came home, and again measured just a tad over 100V AC from earth to trailer.

What would be my next test? Is the array on the container the only thing left to look at?

I am trying to refresh my memory on everything.

Did you remove the ground loop I had discussed earlier? Is this the current configuration of the system?

Then I removed the Neutral-ground bond from the RV distribution panel (that I installed just for the trip) and plugged back into the grid. Almost 0VAC from earth to trailer.

As I recall, this was the same as before the trip. When plugged into the grid, there was very little voltage to earth ground. I would expect this because the shore power has the grounding wire tied to earth ground and the trailer chassis is tied to the grounding wire through the inverters. This would equalize any potential between the chassis and earth ground

 

[Lt.Dan]

I am trying to refresh my memory on everything.

Did you remove the ground loop I had discussed earlier? Is this the current configuration of the system?

View attachment 71335

I did remove the ground loop inside the transfer switch, but it is backwards from your picture. The 2x inverters have the ground connected to the transfer switch, but I removed the shore power from the transfer switch, so now shore power ONLY goes straight to the inverters. The transfer switch is now a pass through since there is only 1 input and 1 output now. Everything else is spot on.

I did realize today, that my stairs are touching a rubber matt, which is sitting on the ground? But I doubt the power is somehow traveling through the stairs?

As I recall, this was the same as before the trip. When plugged into the grid, there was very little voltage to earth ground. I would expect this because the shore power has the grounding wire tied to earth ground and the trailer chassis is tied to the grounding wire through the inverters. This would equalize any potential between the chassis and earth ground

Correct.

 

[FilterGuy]

Like this?


In this diagram, there is still a ground loop through the inverters. There will always be a loop through the inverters because of the chassis connection, but the previous drawing will minimize it's size. Having said all that, I really don't think the ground loop is related to the symptoms reported. Since it is such a PITA to get to the xfer switch. Let's leave it the way it is for now. We can come back to it later.

As discussed prior to your trip, the fact that you have a 3-pole xfer switch tells me the problem of tieing Neutral in and Neutral out does not exist.

In the current configuration, if you flip the xfer switch to grid, the loads won't be powered, but in that condition does the voltage between the trailer and earth still exist when not plugged into shore power?

 

[Lt.Dan]

Its an automatic transfer switch, so I can't change it manually. The generator input (which is where the inverters run to) has priority, so it will always be chosen.

If I flip off the main 50 amp dual throw breaker in the RV distribution panel (that shuts off power to the entire trailer), and the trailer is not plugged into shore power, then the voltage potential still exists between earth and trailer, if that answers your question.

 

[12VoltInstalls]

then the voltage potential still exists

I wonder what Hz the voltage is? Is the container connected to anything electrical other than the camper?

 

[FilterGuy]

OK. I think I have my answer. Flipping the dual pole breaker is pretty close to the same thing...

Just to be sure on a previous question: With the current wiring, the PV to the storage plugged in, the trailer not plugged into shore power, did the bad voltage paper when the Neutral-ground bod was in the breaker box? (As I recall, the bad voltage did appear, but I want to be sure)

This is getting very curious. With the trailer not plugged in, the dual breaker turned off and the grid disconnected from the ATS, .... the AC lines in and out of the two inverters are almost completely disconnected from anything.... and yet we are still seeing the problem.

I say 'almost' completely disconnected for a few reasons:

1) The neutral in on the two inverters are still tied together
2) The neutral out on the two inverters are still tied together
3) There could be some kind of short or miswiring on the lines that are still connected.

How hard is it to get to the AC in and AC out of the inverters? Is it very hard to completely disconnect the AC in?

 

[Lt.Dan]

I wonder what Hz the voltage is? Is the container connected to anything electrical other than the camper?

My meter read it at 59.99Hz, confirming in my mind, this is AC voltage. Shiping container has no electricity within 100ft of it, except the panels that are bolted to it.

OK. I think I have my answer. Flipping the dual pole breaker is pretty close to the same thing...

Just to be sure on a previous question: With the current wiring, the PV to the storage plugged in, the trailer not plugged into shore power, did the bad voltage paper when the Neutral-ground bod was in the breaker box? (As I recall, the bad voltage did appear, but I want to be sure)

Correct, still had voltage between earth and trailer with the neutral ground bond.

This is getting very curious. With the trailer not plugged in, the dual breaker turned off and the grid disconnected from the ATS, .... the AC lines in and out of the two inverters are almost completely disconnected from anything.... and yet we are still seeing the problem.

I say 'almost' completely disconnected for a few reasons:

1) The neutral in on the two inverters are still tied together
2) The neutral out on the two inverters are still tied together
3) There could be some kind of short or miswiring on the lines that are still connected.

How hard is it to get to the AC in and AC out of the inverters? Is it very hard to completely disconnect the AC in?

It's not very difficult, I can give that a try. I'll try tomorrow when I get home from work. ?

 

[Lt.Dan]

Apologies for taking so long. Its been hectic. But I pulled the AC input out of both inverters, totally isolating the input side. I still have 86V from earth to RV right now.

I pulled this out of the first inverter, and thought for sure this was the problem. Sadly not. I will correct this though.



Its unfortunate that MPP recommends 4AWG, but somehow I can barely fit 6AWG without loosing a few strands!!!

 

[John Frum]

Apologies for taking so long. Its been hectic. But I pulled the AC input out of both inverters, totally isolating the input side. I still have 86V from earth to RV right now.

I pulled this out of the first inverter, and thought for sure this was the problem. Sadly not. I will correct this though.

View attachment 71770

Its unfortunate that MPP recommends 4AWG, but somehow I can barely fit 6AWG without loosing a few strands!!!

I suggest ferrules.

 

[Lt.Dan]

I suggest ferrules.

On my to do list! Lol

 

[FilterGuy]

OK.... If I am following along correctly this is the current set-up and the problem persists.




There is not much left to unhook, but let's keep at it.

Next steps
1) Unhook the inverter outputs. (Note: The inverters might say there is a fault after you disconnect the output. If so, content the two neutrals together and try again.)
- Does the problem persist?

2) Disconectt the DC-DC converter
- Does the problem persist?

 

[Lt.Dan]

I'm thinking about rewiring the inverter output as well, and just bypass/remove the transfer switch all together. It doesn't need to be there, in all reality. This will also remove the possibility of the factory wiring that originally went from the generator to the transfer switch, from causing problems.

I'd replace it with new 4/4 SO cable

 

[Lt.Dan]

I'm also wondering if the 18 farad capacitor could be the problem. Thats one thing that is missing from your drawing @FilterGuy. It is strictly wired to the hydraulic pump for the leveling system though.