I have a mobile coffee trailer that is battery operated. We have three EG4LL 48v Batteries connected to two Victron Quattro Inverter Chargers (48v 5000VA 70AMP). When our system is plugged into our trailer storage, it trips the GFI outlet available to us. To solve for this, we have been charging it at our home on a non-GFI outlet, however, this is no longer an option.
After doing some research, I am planning on putting a Victron Isolation Transformer on the input side of my charging system, specifically on the trickle charge port (20amp). My goal is to only use it on the 20amp charge circuit inline between the charge port and the inverters so that we could theoretically charge the system on a regular 15amp extension cord (since 50amp is the only other port we have and we don’t have access to an outlet over the standard 120v).
Would this concept work? Looking at the example wiring diagram in the transformer’s manual it appears that it might but I have spoken to two different solar companies that have experience with Victron and mentioned that the Isolation Transformer is traditionally used on the output side. The second company said that in theory, my idea may work but that it would be best to check this forum before I do since it would be a rather expensive experiment to find out.
Has anyone run into this and has an answer? Alternatively, is there anyone who has another fix for this specific issue?
Why not fix the fault that is causing the GFI to trip?
There must be something causing it to trip, first place I would look is at the grounding of the Victrons. Do they have a Ground-Neutral link relay that connects G-N when not plugged into the supply? Has it developed a fault and is leaving G-N connected as this would trip the GFI.
Do both Quattro do it or just one?
@GUMPY As far as I’ve been aware, the fault would just be that the inverter’s startup surges too high for the standard outlet. We did lower the AC draw as much as we could w/ a cerbo GX since the quattro’s were reading the usual 120v outlet as being below the minimum.
I’ve assumed both Quattro’s are responsible for the trip since they are each connected, however, looking closer at the system, both inverter’s pass battery power through to the breaker panel and subsequent load as well as house the hookups for shore power while only one has the hookups for the trickle charge, which is grounded. I know the trickle charge is connected to this inverter’s AC IN 2.
I’ve included photos of the system for reference, but I believe the wiring setup looks correct. Let me know if you believe that this would need a change up, though. If we can bypass the need for the transformer altogether, that would be ideal.
The fact that you mentioned that it worked on a non GFI outlet made me think it could be a ground fault.
If the two outlets are the same amperage then it can’t be overload, how far down can you restrict the current drawn ?
A transformer will make no difference to over current problems as it just passes what’s on it output to input.
GFCI tripping is a known issue for the MP2 on North American power grids. I haven’t seen any mention of this issue on Quatros before but I would say it is highly likely. They are going to share a lot of the same internal components, which is where the problem is. North American GFCI outlets have a much narrower tolerance that European counterparts.
Most likely the reason we haven’t seen complaints about the Quatros and GFCI’s is because the overwhelming majority of mobile installations in NA have been MP. Mobile installations is going to be where you would usually see GFCI outlets being used to supply the inverter.
Edit: You are not the only one with this problem on a quatro:
@GUMPY The current drawn is down to the lowest we could get it. That part of the Cerbo GX is managed by the trailer manufacturer so I would need to ask them for access to get you the numbers. They haven’t been much help at all, though, since their first design did not have the Cerbo GX and as a result, we couldn’t charge the inverter’s at all and had to get a deep cycle battery for them since they drained too low..
Does the wiring look correct on the photos for G-N per your first question?
@thomasinaz Thanks for the information! Provided the why, do you know of any applicable solutions to the issue? How has the problem been handled for the MP builds? I’m not coming across any solutions in the other two threads. My issue uses just about the same build as the first link minus the MPPT solar setup w/ panels, but, the breaker trips immediately, not after a while. Per the second thread, it appears that the why behind the current leakage was a decent answer but I don’t see anything in there for how I can solve beyond that. What if I were to shut off the breaker panel for the load? If my equipment isn’t running, would I be able to bypass the problem?
The issue is not on the load side, the leakage is internal to the inverter. One person reported success by disabling the ground relay, but that has never worked for me across several installations. For my personal rig, I have an extra 20amp dogbone adapter with the ground lug removed that is only used as a last resort when I have to get a charge and have no other options. Thankfully I’ve only had to use it once in the last few years.
@thomasinaz I will look into the dogbone adapter! I appreciate the recommendation. Back to my original question, by installing an Isolation Transformer at the input side between the trickle charge inlet and the inverter system, would we solve for the internal leak affecting the GFI? If the transformer isolates the A/C circuitry and everything after it, wouldn’t this prevent the GFI from picking up on the leak and tripping?
In theory, yes an isolation transformer should prevent the upstream GFCI from tripping. As the name implies, the input is isolated from the output, therefore the GFCI should not see any leakage created downstream of the transformer. This unfortunately involves more wiring and space for the component, not to mention additional expense.
What happens if there is a phase-to-ground or phase-to-neutral fault INSIDE the trailer when connected to shore power (ground relay open)? In this scenario, would the circuit breaker on the shore power side trip (clear the fault)?
If the ground relay is open while in inverter mode (or if shore is connected with a lifted ground) and there is a fault to ground this would create a dangerous situation. Exposed metal surfaces (the chassis or hull) would become live. You could protect against this by using GFCI or RCD on the output of the inverter. The relay setting has no effect while on shore power.
Full disclosure: I run an RV service center, I do not service marine vehicles. Though they are both mobile applications, some things cross over but some things do not. Isolation transformers would primarily be found onboard marine vessels and not RV’s so that is getting outside my wheelhouse. I will leave that to someone more qualified than myself.
Edit to add: A fault to neutral would still trip the breaker.
I wasn’t willing to come right out and state it, either But, I think you’re correct in both scenarios. I’ve wrestled with whether or not to recommend this to customers before, and I decided not to, though I wasn’t 100% certain. I erred on the side of caution/safety. Still, I’m not certain and would entertain input from others.
you have a ground fault in your step up, most likely related to AC in 2, and the way it is used for shore power charging if that is what you are using when GFCI trips.
DO NOT use an isolation transformer, fixing wiring faults is not it purpose, you are operating a business and the public is exposed to this, get the problem fixed, don’t cover it up.
@kevind1 Thank you for the input, Kevin. Understanding that I am running a business is why I came here for answers as I’m not looking for shortcuts. Endangering the public is definitely not something I am wanting to do.
That being said, I am curious to know more on your take concerning the wiring being an issue. Provided the pictures I sent above in the thread, do you think that the hookups for AC IN 2 are just done incorrectly or damaged in some way? I’ve been double checking everything I can regarding the wiring and am open to whatever feedback can steer me in the direction of what needs to be fixed. Do you disagree with the conversations had above and if so, why?
@thomasinaz Our business is actually in Arizona. How much would you charge for us to bring it in and have you look it over for a second opinion? Or do you think seeing it in person wouldn’t change your opinion? We are in the West Valley of Phoenix.
can you post pics of the inside of the breaker panel make sure where green and white wires connect is clear, also if there is a jumper between where white and greens connect.
assuming AC 2 input goes to a plug end, and AC 1 input goes to a shore power 120/240v plug on side of trailer that you don’t use correct
do you know how the ground relay is programed? can you post screen shots of the config
wring diagram if your able to draw one
with that can start to help
it is most likely a neutral (white wire) to ground ( green wire) connection either in the panel or some where in the trailer or relay programing
and a pic of the inside of the plastic box to right of breaker panel
FYI
an over current will not trip a GFCI
leakage will
A GFCI looks at power leaving and coming back hot to neutral (black to white) if there is 5ma of leakage, current not coming back it will trip.
it is most likely going to ground some where.
or
if you have a very long extension cord and are pulling a lot of current, induction between the wires in the cord can also appear as leakage and cause a trip.
But, I think you’re correct in both scenarios. I’ve wrestled with whether or not to recommend this to customers before, and I decided not to, though I wasn’t 100% certain. I erred on the side of caution/safety. Still, I’m not certain and would entertain input from others.