Lithium battery backup trips GFCI taking a charge while feeding Reliance transfer switch

[zimm]

Ecoflow Delta Pro 2 lithium battery/inverter acting as a UPS to a 6 circuit, Reliance transfer switch. The Ecoflow is plugged into a dedicated 20 amp outlet next to the panel to stay charged. I believe the GFCI is tripping because the Reliance panel doesn't switch the neutral.

Since the outlet is in a garage, removing the GFCI isn't OK. A grounded 3 to 2 prong adapter doesn't seem correct either. Or can the Reliance be modified to switch neutrals? Is there a code compliant way to have this system work properly? Or abandon the UPS feature and only power the Reliance panel during an actual power outage?

 

[jaggedben]

Ecoflow Delta Pro 2 lithium battery/inverter acting as a UPS to a 6 circuit, Reliance transfer switch. The Ecoflow is plugged into a dedicated 20 amp outlet next to the panel to stay charged. I believe the GFCI is tripping because the Reliance panel doesn't switch the neutral.

I might have to draw this one out, but my initial take is that it's the Delta's fault, not the Reliance's.

...

Or abandon the UPS feature and only power the Reliance panel during an actual power outage?

Probably the most straightforward answer.

 

[ron]

If you are not switching the neutral, then the alternate source (UPS or generator) to the transfer switch is not a separately derived source and should not have a N-G bond in the alternate source.

 

[zimm]

If you are not switching the neutral, then the alternate source (UPS or generator) to the transfer switch is not a separately derived source and should not have a N-G bond in the alternate source.

It's not. I looked it up and the Ecoflow has a floating neutral like a portable generator. But something with the grounding path on the transfer switch isn't playing nice with the GFCI. I googled it and it happens to everyone trying to charge a portable power supply while using this style transfer switch.

 

[jaggedben]

Unless the battery units' input and output neutrals are galvanically isolated I think it's gonna happen in this setup, as there are parallel paths for load neutral current through the unit and the breaker panel. I believe that avoiding it would require a 'double conversion' style UPS with a transformer. Probably makes for a more expensive unit which is why most don't do it. And if you can't take the unit apart to find out without voiding the warranty...

It is also correct that if you had different transfer equipment that switched the load neutrals it shouldn't be a problem. So I'll backtrack on blaming one or the other. It's the combo that doesn't work.

 

[wwhitney]

Unless the battery units' input and output neutrals are galvanically isolated I think it's gonna happen in this setup, as there are parallel paths for load neutral current through the unit and the breaker panel.

Yes, if the Ecoflow has the neutral conductor on its charging input and it outputs solidly connected, the usual way of hooking this up will create a neutral loop: main source - GFCI - Ecoflow charging input - Ecoflow output - Reliance transfer switch - main source. The GFCI in the middle of the loop will trip as the neutral current from charging the Ecoflow divides on the two return paths, or some of the neutral current from the output side connection travels back through the input side connection.

To avoid the neutral loop, how about charging Ecoflow from one of the circuits on the Reliance transfer switch, which you always keep set to "Grid" (I'm assuming a manual transfer switch)? And then on the Ecoflow power ouput, you just route the one or two (120V or 240V, not clear what this equipment does) ungrounded conductors back to the Reliance alongside the input conductors to the Ecoflow

That way there is only one neutral path, yet both the charging input ungrounded conductors and the output ungrounded conductors are routed with the common neutral. Although now if you need GFCI it would need to be on the supply to the entire Reliance panel, which might be problematic.

The other thing you can do is just unplug the Ecoflow before switching any of the Reliance circuits from Grid to Backup. Or if your goal is to keep the Reliance circuits on "Backup" mode most of the time, and just switch them to "Grid" if the Ecoflow is out of commission for some reason, install a disconnect on the grid supply to the Reliance that also disconnects the neutral, and leave it off.

Cheers, Wayne

 

[zimm]

Interesting idea on moving the charging circuit to one of the Reliance circuits. That would be very easy to do and I can see if that stops the tripping.

So my other options are not to use the UPS feature, or swap out the GFCI (in this picture it's removed for troubleshooting). It is a nice feature to have some of the circuits like the fridge and freezer on UPS.

Here's the set up:

 

[wwhitney]

Interesting idea on moving the charging circuit to one of the Reliance circuits. That would be very easy to do and I can see if that stops the tripping.

The idea I suggested is not "easy to do" as it involves using a single neutral conductor for both power to the Ecoflow and power from the Ecoflow. So it would require modifying one of those cords, as well as wiring up a charging receptacle in a particular way. So I don't recommend trying it.

Also, the ProTran2 is a little different than I thought, it's effectively 6 single pole transfer switches ganged together. So more thought is required to determine if something along those lines would even work.

What is your desired default state? Will it be all the Pro/Tran2 circuits on "Grid", all on "Backup", or a mixture of the two?

Cheers, Wayne

 

[wwhitney]

Unless the battery units' input and output neutrals are galvanically isolated I think it's gonna happen in this setup, as there are parallel paths for load neutral current through the unit and the breaker panel. I believe that avoiding it would require a 'double conversion' style UPS with a transformer.

So one solution would be to get a 1800W 120V isolation transformer and install it between the GFCI receptacle and Ecoflow. That will break the neutral conductor loop, while limiting the GFCI protection to the input side of that transformer. The output side of the isolation transformer would still be grounded when the Eco flow is attached both to it and the Pro/Tran2.

Another possibility that probably would require too much surgery on the internals of the Pro/Tran2 would be to try to convert it from 6 single pole transfer switches into 3 double pole transfer switches. But that would involve effectively adding two neutral busses, one for Generator and one for Grid, replacing all the breakers with double pole breakers, and rewiring every other 3 position Grid/Off/Gen switch to switch the neutral instead of an ungrounded conductor, along with putting handle ties on those switches.

At which point you'd be better off just installing a normal "backup loads panel" along with a 3 pole transfer switch. Or using whatever solution Ecoflow sells for this purpose.

Cheers, Wayne

 

[zimm]

What is your desired default state? Will it be all the Pro/Tran2 circuits on "Grid", all on "Backup", or a mixture of the two?

I like to keep it as a mix. I have some circuits on UPS, but not the furnace/air handler because it pulls enough watts to make the Ecoflow cooling fans kick into high gear.

At this point, I think I'll just leave the GFCI off that outlet and let it run the Ecoflow. I can put the GFCI back in when it's time to sell the house. It's not "correct" but I won't use that outlet for extension cords, I'll use the GFCI on the other wall.

 

[wwhitney]

At this point, I think I'll just leave the GFCI off that outlet and let it run the Ecoflow.

A less bad solution would be to install a simplex receptacle that is right next to the Pro/Tran2, and to route the charging power cord directly alongside the power output cord to the Pro/Tran2. As you will still have a loop in the neutral conductor, with current dividing along the two routes, creating EMF.

Basically the Pro/Tran2 is made for connecting up a power source that has no other connection to the house wiring. While the Ecoflow is a power source with an additional connection to the house wiring, creating the problematic neutral loop.

Cheers, Wayne

 

[zimm]

That's a great idea. I can put an old work box and simplex outlet directly below the pro-tran and put the GFCI back into the duplex. Since I made the access below the service panel it's very easy to add circuits. Then less worry about someone using an extension cord with a non-GFCI.

Thanks for the advice.

 

[wwhitney]

Thanks for the advice.

Just to be clear, I'm not advising you to do that, as it's not the right solution. You should pick one of the correct solutions, even though they are more complicated or more expensive. The simplest is a sufficiently rated 120V plug-in isolation transformer between the receptacle and the charging input on the Ecoflow.

Cheers, Wayne

 

[Todd0x1]

The gfci is tripping from its load side neutral getting connected to ground due to the path back to the MBJ through the reliance. You could wire up a changeover switch between the delta ac input, its output, and the inlet to the reliance so when you switch it to backup mode it disconnects line and neutral from the delta.

 

[wwhitney]

The gfci is tripping from its load side neutral getting connected to ground due to the path back to the MBJ through the reliance.

It's even simpler than that. The neutral on the Pro/Tran2 inlet is connected to the panel neutral bar, as is the neutral on the GFCI receptacle. And I believe the Ecoflow's neutral on the charging cord is connected straight through to the neutral on its receptacles. So with both cords connected, that's a big neutral loop.

. You could wire up a changeover switch between the delta ac input, its output, and the inlet to the reliance so when you switch it to backup mode it disconnects line and neutral from the delta.

In post #10, the OP indicates a desire to leave some of the Pro/Tran2 circuits on Backup all the time. That requires letting the Ecoflow be simultaneously connected both for charging and for output.

Cheers, Wayne

 

[Todd0x1]

It's even simpler than that. The neutral on the Pro/Tran2 inlet is connected to the panel neutral bar, as is the neutral on the GFCI receptacle. And I believe the Ecoflow's neutral on the charging cord is connected straight through to the neutral on its receptacles. So with both cords connected, that's a big neutral loop.


In post #10, the OP indicates a desire to leave some of the Pro/Tran2 circuits on Backup all the time. That requires letting the Ecoflow be simultaneously connected both for charging and for output.

Cheers, Wayne

ah, missed that part