Two inverters for 50 amp service

[Cptnvideo]

We have a Go Power IC Series 3000 watt inverter and 50 amp service on our 5th wheel. I have 2 complaints about it that I wasn't aware of when it was installed.
The monitor panel only monitors Line 1. The current limit function only limits current on Line 1. So when plugged into a relative's 15 or 20 amp service, we can only see and control what is being drawn on Line 1. And I would like to control the current on both lines so we wouldn't inadvertently trip the breaker feeding the RV.
Is it possible to have two 2000 watt inverters (one on each line)? My dealer says no. But I don't see why not as nothing in the RV runs on 240 volts.
Correct me if I'm wrong, but to create 240 VAC for two 120 VAC lines, the 2 lines have to be out of phase. And if the lines were in phase, 0 VAC would be measured across the 2 lines. So the output of the 2 inverters would be out of phase when plugged into a 50 amp service and in phase when plugged into 30 (or less) amp service. But I don't see an issue with that. Am I missing something?

[Cptnvideo]

TechWriter wrote:

Cptnvideo wrote:
TechWriter, my current GoPower IC 3kw inverter/charger does incoming and outgoing L1 and L2. The problem is it only monitors and controls the current on L1.
Does the Victron Multiplus II monitor and control current on both lines?

Not if incoming AC is connected via a dogbone.

I guess that is one more reason with sticking to two 2kw GoPower IC Series inverters. Totally separate outputs with monitor and current control on each line - if I connect only to Line 1 of each inverter. Line 1 to Line 1 of inverter 1, Line 2 to Line 1 of inverter 2.
I wish one of these companies would include load sharing with monitor and current control on both legs in a single unit. In my current setup, I can see how much current is being drawn on Line 1 but not on Line 2.

[TechWriter]

Cptnvideo wrote:
TechWriter, my current GoPower IC 3kw inverter/charger does incoming and outgoing L1 and L2. The problem is it only monitors and controls the current on L1.
Does the Victron Multiplus II monitor and control current on both lines?

Not if incoming AC is connected via a dogbone.

[Cptnvideo]

ktmrfs, doesn't your current example apply to any 50 amp RV without an inverter?
What is the difference between with and without an inverter as far as neutral current applies?

[ktmrfs]

wa8yxm wrote:

Cptnvideo wrote:
Nice post, wa8yxm. But doesn't really answer my question. BTW, neither did GoPower tech support.
Since I don't have any 240 VAC appliances, I don't see why I couldn't have 2 separate inverters and no need to sync them.

The answer to that is rather complex and involves the neutral line
With two inverters it is possible that if they are not properly phased the neutral could be carrying way more current than it is designed to haul.

120/240/120 volt Power. like a house.. Current flowing in both legs does NOT flow in the neutral So if you have say 1,000 watts of load on L-1 and 1,500 watts load on L-2 the neutral is hauling only the current from the difference 500 watts or bout 4.1 amps. But if you have two 3,000 watt inverters is 6,000 watts or 50 amps.. that's the maximum for the neutral line.. I don't like maxing out wires.

Even hooked to shore power you will end up with anywhere between 0 and 50A in the neutral. It would be rare to be either 0 or 50A, but I agree, two inverters phased together will have the combined current in the neutral and 1/2 the combined current in each hot leg.

[Cptnvideo]

TechWriter, my current GoPower IC 3kw inverter/charger does incoming and outgoing L1 and L2. The problem is it only monitors and controls the current on L1.
Does the Victron Multiplus II monitor and control current on both lines?

[Cptnvideo]

I should point out that my primary interest is load sharing when connected to a 15/20 amp source. I want to be able to utilize 80% of the incoming amps and make up any extra usage with solar charged batteries.
I guess my original post wasn't very clear.

[Cptnvideo]

Wa8, you keep mentioning 2 3kw inverters.
I have one now. I might switch to two 2kw inverters, not to 2 3kw inverters.

[CA_Traveler]

If the inverters are using part or all of their output from the pedestal input to them then phasing is not a option, it's a given because all RV plugs are single phase. If they are not using pedestal power then all of their output power comes from the battery and their outputs are independent so phasing is a non issue. Unless you're thinking their output neutrals or hots are connected.

[wa8yxm]

CA Traveler wrote:
I don’t see that as a problem at all. While on shore power the 2 inverters are synchronized. If not on shore power the 2 inverter outputs are derived from the batteries and not the inverters AC inputs.

While you are correct the problem is the rating of the Neutral Wire..

Normally the neutral carries only the difference between L-1 and L-2 So if you have 20 amps on L-1 and 14 on L-2 the neutral hauls only six amps.. IF the two inverters are properly phased.. Same thing.
if they are not then the Neutral in this case can haul anywhere from the same six up to 34 amps and with two 3,000 watt inverters up to 50 amps... Should not be a problem but I do not like to "Test the ratings" on wires. That's a good way to have some folks show up for a house call (The Fire Dept).

[TechWriter]

Cptnvideo wrote:
So the output of the 2 inverters would be out of phase when plugged into a 50 amp service and in phase when plugged into 30 (or less) amp service. But I don't see an issue with that. Am I missing something?

Or, buy a single Victron Multiplus II inverter and run both L1 & L2 into and out of it.

[Cptnvideo]

Don (pianotuna), we do typically limit our current draw to a couple amps less than breaker size. Unfortunately, with our current single inverter, only L1 is limited. And that is why I would like to switch to 2 inverters.
The 2kw inverters are $1600 on Amazon and our 3kw is $3121. Anyone want to buy a 3kw that's been used 6 months?

[Cptnvideo]

I appreciate the concern.
We also have 1600 watts of solar and 618 ah of LFP batteries.
I started thinking about the 2 inverters when we were at Linda's son's home in OK and the temperature was over 90°. We had no problem running 1 A/C on his 15 amp outlet, but being able to run a 2nd A/C for an hour or so would have been nice. With load sharing and solar, I would have only drawn the batteries down about 60 or 80 ah and still be fully charged by sundown.

[CA_Traveler]

BTW Do you know how your friends house is wired? My house has 8 garage and outside 15A plugs, with a GFCI, 240' of 14 gauge wire and a 15A CB. When I plugged my saw into the last outlet (wasn't aware of the wiring) it would not cut a 2x4. Yes it's wired to NEC code, built in 2006. Fortunately there is also a dedicated 20A plug on a deciated 20A CB with much shorter wire for my saw or I would have had to add an adequate circuit.

[CA_Traveler]

Cptnvideo wrote:
"Personally I don’t like what the Cptn wants to do but he’s gotta do what’s best for him."

Why, CA? All I want to do is have load sharing and monitoring on L1 and L2 instead of just L1.

On a hot day what is the value of 1+ hours of A/C use? What happens on the day you’re driving and the A/Cs are running? Dead batteries along the road? Ruined alternator due to overload? Certainly possible. Just considering the responses so far I’d suggest professional vetting and design for this rather unique application as without that there could be unintended issues. Design problems, wiring size, loads, etc.

Are you aware that a 15A plug implies it’s one of a number on that circuit? What are on the other plugs drawing current? Any embarrassment asking your friend to turn his house stuff off? 20A is better PROVIDED it’s the only dedicated 20A plug on the circuit.

We are all trying to help, but unintended consequences are possible.

But it’s just what I wouldn’t and do and I was very carefull with all loads when on a 15A plug. My son and I installed a 50A circuit at his house in hot Sacramento and used 100’ of 50A cord to reach the side street. 50A also installed at daughters house.

[Cptnvideo]

CA, our center unit is also a heat pump with soft start. We have used that unit in both heat and cool modes while going down the road. While running, our A/C units each draw 9.6 amps.