I have a Victron Multiplus Compact 12/2000/80 inverter/charger. It has used only the battery as its DC input for a couple of years. Recently I wired up the AC input using an 8ft 10awg extension cord with the female end cut off. I was very careful to make sure I wired the black > L, white > N, green > G.
I then tested the charging by plugging into an RV campground 20amp electrical outlet, using a 50ft 12awg extension cord. I watched in the VictronConnect app as it started a timer to switch over from DC input to AC input.
The moment it swapped to AC input, the campground outlet circuit breaker tripped. I reset it, and it tripped again as soon as the inverter swapped over. I then set the max charging draw on the inverter to about 10amp through the VictronConnect mobile app, and tried again. Again, the circuit breaker tripped.
I then set up and started my gas generator, then plugged the inverter AC input directly into it (no 50ft extension cord). This time, the inverter restarted when it swapped over. I tried a second time with the same results.
What could the issue be? If the cause is not readily apparent, what can I test or try to narrow down the possible causes?
Again, the inverter has worked fine for a couple of years when being run off of the DC input.
Here is a concise description of my wiring:
DC Input – RV Battery
Battery > 200a mpANL fuse > Inverter
AC Input – AC shore power
RV camp 20amp outlet > 50ft 12awg extension cord > 10awg 8ft extension cord with female end cut off > Inverter
Also, I can get additional monitoring components if that would help diagnose the issue. Im aware of V.E. Direct, but Im not sure if it would help more in this situation over the VictronConnect bluetooth data.
You probably have an MEN link on your system. Did you trip a circuit breaker or RCD with ground-neutral protection? If you have a ground-neutral connection on the inverter you will need to break it. There is an internal relay that makes that connection when in inverter mode and opens when connected to shore. Have an electrician look at it and configure it correctly.
This is the first I’ve ever heard of a “MEN link”, Ill look into that.
Im not sure about the circuit breaker / RCD with ground-neutral protection, it was a typical RV campground circuit breaker as far as I could tell. I can test it again and check though. What exactly would I be looking for, that would tell if its what you’re asking about?
Unfortunately, Im in a remote area without much access to an electrician for a little while. I did do all of the electrical work on my rig though. Is this something I could take care of myself?
If so, are you aware of any guides to look for information?
I wanna make sure we’re on the same page; you want me to use a multimeter to check for continuity between earth and neutral on the AC Input side, while the inverter is running but disconnected from shore power? Or did you mean the AC Output side?
And where would you recommend checking?
For the AC Input, thats easy since I can just test all combinations of the male prongs.
For the AC Output, could I test at an electrical outlet? Seems like itd be a bit dangerous to do while the inverter is running, would I be able to check while its off?
Turn it off. If there is a MEN link that someone made you dont need the intverter on. If you dont want to do it take it to an electrician. AC is dangerous.
Gotcha. In that case, I’ll turn the inverter off and then test for continuity between earth and neutral on the AC Output side at one of the interior RV electrical outlets and report back what I find.
Is there anything else I should test for while I’m there?
I turned the inverter off via the VictronConnect app, and verified it was off by checking the microwave to see if the light came on when I opened the door (it didn’t). I then did the following;
Disassembled an electrical outlet
Checked that ground/neutral had continuity, which yes it did.
For fun, I checked ground/live, which also had continuity
I then checked live/neutral, which had continuity (weird, but I think AC is different than DC in that way).
To be extra sure, I completely removed the electrical outlet, so it was just bare wires sticking out of the wall
I tested all configurations for continuity, and yes they all still did
So from what you were saying, it sounds like there is a MEN Link.
What does this mean?
And more importantly, what can I do to resolve this issue?
I did all the electrical work myself, and I was always very careful to keep any wires from shorting. It seems like it either must be happening in the inverter, or in the RV AC circuit breaker (which is after the inverter).
The inverter connects directly to the lithium 12v battery with a 200amp inline ANL fuse to the DC Input.
For the AC Output, it runs to a standard 120v outlet. All of the 120v wiring in the RV is plugged into one of the outlet connections, except for the fridge. A separate line for the fridge (also connected via the electrical outlet through a standard 3-prong male plug) runs to a 15amp 120v GFCI circuit breaker, and then from there to the outlet that the fridge plugs into.
For the AC Input (not pictured), it’s just an extension cord that I cut the female end off of and then connected to the inverter. The male end is free to be plugged into a generator or any standard 120v outlet.
Its worth noting that I tested for ground/neutral continuity at an outlet in the section labelled “Various RV Outlets” in the diagram.
Turn the Multiplus off, and then check the ac input and output connections, inside the outlets, at the GFCI breaker and anywhere else the 120V ac goes to see if you can find a wired connection between ground and neutral conductors. Often this is installed in the distribution box / breaker box / consumer unit but you do not have one. This link wire is not required as the Multiplus creates this link when you are not connected to shore power. This is described in the manual download from Multiplus 2000 120V manual.
You will need to remove the ground neutral bridging wire AND check your Multiplus settings to make sure that the ground relay remains enabled as per default setting. You really need to be absolutely sure that you understand what is required and the safety aspects here.
When I built this system I didn’t install a “link wire” anywhere, I did my best to keep ground/neutral/live completely isolated. It sounds like you’re saying that when the Multiplus is off, there shouldn’t be any ground-neutral continuity, and if there is then that would indicate a ground-neutral short somewhere?
I’ll do what you suggest to try to find where this short is and fix it, and I’ll report back my findings.
For the setting you mentioned, “ground relay remains enabled as per default setting”; I don’t believe I ever changed that setting. Looking in the VictronConnect app (via the connected bluetooth dongle), I dont even see that setting anywhere. How would I verify the setting is correct?
Hence why using an electrician is advised. Tripping the camp site breaker is often caused by the earth leakage being set off rather than being overloaded. It is also why at some stage the help dries up because it is getting outside of Victron equipment issues into general electrical installation stuff and that does not always translate internationally with different practices.
Settings are usually done via the mk3 to USB adapter on an Android phone and Victron Connect or PC/laptop and VE Configure or if you have a GX device connected to the internet then you can download / upload settings via VRM and edit them on a PC/laptop in VE Configure. The dongle is for monitoring.
Gotcha; I’ve just ordered the “Interface MK3-USB-C”. Should arrive in the next day or two and then I can verify/update any needed settings.
What you say makes sense, this electrical stuff is complex and dangerous. I’d love to leave it to the professionals, unfortunately its not an option at the moment. Even when it was, every electrician I called refused to even come take a look at it when I told them the installation was in a vehicle. Maybe I just didn’t call enough people.
As it turns out, the issue was simple; in the fridge breaker box, both the neutral and the ground wires were connected to the neutral bus bar.
Disconnecting the input/output ground wires from the bus bar and connecting them together directly resolved the issue. The inverter is now correctly charging the battery via the generator, and later Ill be back at camp to verify that connecting to shore power doesnt trip the shore power breaker.
Thanks to everyone for their help! Even though it was a simple fix, it would have taken me far longer to troubleshoot on my own.
