EG4 3000 based RV GF problems.

[parker-lhe]

Hello! New here but have experience building automotive and solar based electrical systems. This is an interesting problem and I am hoping someone here has run across this or can point me where to start looking next.

My system is a RV based. Offgrid with shore power hookups. I have a eg4 3000 AIO with 2 lithium 48V 5.12kw batteries. Solar is 6 550W Renogy panels wired in series, roof mounted on a custom rack. The frames of the solar panels are connected to the frame/chassis of the RV by the nature of the roof rack. This is confirmed with a continuity meter.

I am working on setting up a way to charge the batteries from the engine via an auxiliary alternator. The aux alternator goes to its own 12V Lead acid bank. This system shares ground with the chassis so it is not isolated. I have a Renogy 3000W inverter hooked up to this 12V lead acid bank. The output of the Renogy 120VAC is hooked into the A/C input side of the eg4 3000 via a selector switch. I can switch between the shore power or the on board inverter that is powered by the engine is the gist of it.

Now when I turn on the Renogy inverter it powers up fine and outputs the 120VAC. When I attach the eg4 A/C input to the output of the Renogy inverter the inverter throws a GF error. Without attaching the eg4 to the output I can plug in tools and devices into the output of the inverter just fine and use them.

When I am on shore power the GFCI on the pole doesnt trip. So something about the inverter being connected on the DC negative side to chassis is causing some leakage to trip the internal GF on the inverter.

Now when I disconnect my PV array from the eg4 this does not happen. The inverter / engine can power the eg4 and charge the lithium batteries just fine.

I tested the PV+ and PV- and both are isolated from the frame / chassis when disconnected. Doing some reading these AIOs do leak current between the PV and A/C side.

What should be my next steps to get this working? It looks pretty easy to disable the GF detection on the Renogy inverter but I don't think that is the "best" method of solving this. I want to make sure I am not overlooking something.

Thanks!

 

[sunshine_eggo]

The typical AiO supplies the N-G bond when inverting.

When supplied with AC, they break the internal N-G bond as the expectation is the incoming source is providing an N-G bond (like shore power).

The Renogy likely does not provide a N-G bond.

GF errors and GFCI trips are commonly cause by multiple N-G bonds or no N-G bond.

 

[justinm001]

Welcome to the forum. Honestly I don't trust anything Renogy so can't help you with your issue.

I am curious though, Why did you decide to go ALT to Lead acid 12v to AC inverter to another AC inverter to DC battery? Why not just get a 12/48 DC to DC converter or a few of them?

-- I just realized Victron doesn't make 12/48 so you'd have to get another type.

I'd suggest going with 24v alternator as there's plenty of 24/48 (I run 4 Victrons this way) But even better is going 48v Balmar and running a Wakespeed/Zeus controller. There are some Jeep/dodge 48v alternators on ebay that might work too.

 

[justinm001]

The typical AiO supplies the N-G bond when inverting.

When supplied with AC, they break the internal N-G bond as the expectation is the incoming source is providing an N-G bond (like shore power).

The Renogy likely does not provide a N-G bond.

GF errors and GFCI trips are commonly cause by multiple N-G bonds or no N-G bond.

You're spot on like always. Victron has an option on its inverters to turn this on/off (below). Wonder if OPs does.

 

[parker-lhe]

I am curious though, Why did you decide to go ALT to Lead acid 12v to AC inverter to another AC inverter to DC battery? Why not just get a 12/48 DC to DC converter or a few of them?

I had the inverter left over from a previous project. Also, having the AIO handle all the charging the lithium seems to simplify things. At this point I am not changing the auxiliary alternator setup as it is already purchased, installed, and operating correctly.

I am going to investigate to see the Renogy inverter and see if it is providing a N-G bond or not. Quick googling shows it does have a N-G bond wire inside.

 

[sunshine_eggo]

You're spot on like always. Victron has an option on its inverters to turn this on/off (below). Wonder if OPs does.

View attachment 205579

Yep. With that unchecked it never provides N-G bond under the presumption that it's at the AC panel or provided by grid. Even when checked, it releases the N-G bond when supplied by AC input current.

In parallel configurations, it's important that only one inverter be configured with the ground relay enabled. In my 120/240V setup, the L1 inverter is check, and the L2 inverter is not.

A few Chinese AiO have the option in settings. Others have a screw you remove to always disable it. Some don't supply it at all (my PowMr 24/3000 is this way).

 

[sunshine_eggo]

I had the inverter left over from a previous project. Also, having the AIO handle all the charging the lithium seems to simplify things. At this point I am not changing the auxiliary alternator setup as it is already purchased, installed, and operating correctly.

I am going to investigate to see the Renogy inverter and see if it is providing a N-G bond or not. Quick googling shows it does have a N-G bond wire inside.

If so, voltage between N-G should always be 0. Voltage between L and G should always be 120V.

 

[parker-lhe]

Checking continuity shows the Renogy inverter has a N-G bond inside the unit. This checks out with people who have taken these apart.

 

[sunshine_eggo]

Is the renogy G bonded to chassis?

Is the Aio G bonded to chassis?

 

[parker-lhe]

The AIO is bonded to chassis. Both through the enclosure and the "ground" wires on the input and output of the A/C side.

The Renogy becomes bonded through the A/C ground wire that comes from the AIO box. I can bond the enclosure of the Renogy to the chassis if needed.

Here is some interesting findings from messing about with it. When there is plenty of solar. The Renogy has no problem and doesn't trip the GF. When the solar is disconnected with the disconnect the Renogy doesn't have a problem powering the AIO. Its when there is no solar power but the panels are still hooked up (dark outside) then the Renogy trips the GF. Weird!

 

[parker-lhe]

I think you are on to something, when it switches over to "line" and changes the bonding of the wires. Maybe that moment trips the Renogy?

Could also be a ground loop problem of the A/C ground and neutral and the chassis ground.

 

[parker-lhe]

Well I adjusted some settings on the eg4 and now I cant get the inverter to throw a GF. I guess this is solved till I can get it to replicate the fault again.

If it keeps faulting ill look into replacing the Renogy inverter with something like the BB1248120 from Sterling Power

 

[parker-lhe]

Ah well that was to hopeful I suppose. Got the Renogy inverter to throw a fault. Going to order a 12V to 48V battery to battery.

 

[justinm001]

Ah well that was to hopeful I suppose. Got the Renogy inverter to throw a fault. Going to order a 12V to 48V battery to battery.

That sterling power device looks amazing. Let us know how it works!!!

 

[parker-lhe]

I did try removing the cable that connected the 12V auxiliary batteries to the chassis to eliminate any kind of ground loop issue between the Renogy Inverter and eg4. Still caused the Renogy internal GF to trip. Such a weird problem.