48V inverter connected to 12V inverter for RV setup sanity check

[justinm001]

I'm about to start my 48V addition and need some double checking and ideas. Currently I have all Victron: CerboGX with 50touch, 150/100 MPPT, Lynx, power in, 2x Lynx Distribution, Lynx shunt all 1000a. Smartshunt 500a, 12V Quattro 5000w 120V inverter, 48V Quattro 5000w 120V inverter. 2xEG4-LL 12V 400AH batteries and 2xSOK 48V 100AH batteries (on order). 18 Renogy 100w panels (6x3 setup) installed and another 12 panels waiting to be installed will order 6 more so 3600w total on roof, have 2x320w panels extra maybe for trailer roof? Both inverters are rated for 100a on each of the 2 inputs and outputs. I have a 20k 240v genny and normal 50amp 240v shore connection. 12V 300a dedicated 50DN alternator with WS500 setup for lithium profile No 240V devices on coach and have 12V lighting.

I use this coach mainly for day or weekend trips and plan on using its solar/batteries almost exclusively. Have about 150w constant drain from various devices when not in use and about 15kWh per day when in use. Have 20kW total battery power and make about 10kW per day in solar. Sunny days mean more solar but more AC so more usage. Depending on where we camp we might have free shore power. We also get freeish alternator power while driving. I use it at least once a week.

Plan is to run shore and genny to both inputs of the 48V inverter then run from Out1 of 48V to input1 of 12V inverter and use powerassist to be able to get 10kw inverter power as needed to both outputs of the 48V inverter which feed into each leg on the breaker boxes. I'll have a black to out1, red to out2, white to neutral, and bare to ground going from inverter to breaker panel 1 then from panel 1 to panel 2. Im unsure of the gauge wires to the panel or between the panels.

With this setup it seems I'm limited to the output neutral wire gauge as if I have 6/3 wire i'll be limited to a 55/60 amp max and if 4/3 i'll be at 100amp max. If I want to be able to safely pump out 100amps on each side or max my genny 20k output limit what is the best option? Or am I incorrect and neutral amperage not as important?

Also with this setup I'll have 50amps coming from shore to in1 on 48V, could I also have 50amps coming from shore to in2 on the 12V with both grounds and commons shared? Or would I need to set the limit to 25 amps for each?

I'm a bit confused at the setup as I have 6 AC units running 15amps with a LRA of 50amps and the coach was setup to run a lot of equipment all over the genny and all 120V. The load was evenly distributed over both legs but still share the common which are all the same gauge.

As far as the configuration, i'm thinking I'll need to get a 2nd Cerbo, setup the solar on 48V and keep both systems separate. The idea is I want it to drain the 48V power first then use the 12V power since it shares lighting.
How low should I allow the SoC get on the 48V before I disable its outputs?
How should I best program the 12V system so it'll use the 48V inverter power first but not use?
If I have it set to keep the 12V at 100% then I lose freeish alternator charge when I'm driving. Any tips on programming to get it to use this power too? Like if 48V batteries are under 75% SoC and alternator is on then use 12V power as long as its 90%+

 

[sunshine_eggo]

Plan is to run shore and genny to both inputs of the 48V inverter then run from Out1 of 48V to input1 of 12V inverter and use powerassist to be able to get 10kw inverter power as needed to both outputs of the 48V inverter which feed into each leg on the breaker boxes. I'll have a black to out1, red to out2, white to neutral, and bare to ground going from inverter to breaker panel 1 then from panel 1 to panel 2. Im unsure of the gauge wires to the panel or between the panels.

My interpretation: the 48V is providing the initial 5000W due to passthru on the 12V. If 5000W is exceeded, the 12V provides additional 5000W via powerassist.

"both outputs" = AC out 1 and AC out 2 to L1 and L2, respectively? AC out 2 is ONLY active when the unit is provided with ac input power. When it is active, it is connected to AC out 1 via a relay, so it is effectively just another place to pick up AC out 1.

When inverting, L2 will be dead.

With this setup it seems I'm limited to the output neutral wire gauge as if I have 6/3 wire i'll be limited to a 55/60 amp max and if 4/3 i'll be at 100amp max. If I want to be able to safely pump out 100amps on each side or max my genny 20k output limit what is the best option? Or am I incorrect and neutral amperage not as important?

If joining L1 and L2, N is your limiter. Even if only using 20A on L1 and 30A on L2, there's 50A on N.

Also with this setup I'll have 50amps coming from shore to in1 on 48V, could I also have 50amps coming from shore to in2 on the 12V with both grounds and commons shared? Or would I need to set the limit to 25 amps for each?

The Quattro can only draw from one or the other AC inputs, not both. You should set the AC input current limit for each input based on the source.

I'm a bit confused at the setup as I have 6 AC units running 15amps with a LRA of 50amps and the coach was setup to run a lot of equipment all over the genny and all 120V. The load was evenly distributed over both legs but still share the common which are all the same gauge.

On a true split phase system, N only carries the current based on leg imbalance. In the above example, 20A on L1 and 30A on L2 would result in only 10A on N. If L1 and L2 are both using 50A, then N carries 0A.

As far as the configuration, i'm thinking I'll need to get a 2nd Cerbo, setup the solar on 48V and keep both systems separate.

Yes.

The idea is I want it to drain the 48V power first then use the 12V power since it shares lighting.
How low should I allow the SoC get on the 48V before I disable its outputs?

5-10%?

How should I best program the 12V system so it'll use the 48V inverter power first but not use?

This will be the behavior by default. If either quattro is fed AC, it passes through the AC to loads and charges with any excess current if needed.

Feeding the 12V with 48V inverter will force the 12V to pass power from the 48V and charge with any surplus.
.

If I have it set to keep the 12V at 100% then I lose freeish alternator charge when I'm driving. Any tips on programming to get it to use this power too? Like if 48V batteries are under 75% SoC and alternator is on then use 12V power as long as its 90%+

I can't envision a way to make that happen solely with the Victron hardware in the manner described. You could force the 12V to "ignore ac input" and force inverting when battery is in the peak voltage range.

Your post is essentially word soup, and it depends on the ability of the reader to translate the words to visuals. Vigorously recommend you sketch everything out. You appear to be a novice proposing to do aggressively typical things. it's worth your effort to sketch up a diagram.

 

[justinm001]

My interpretation: the 48V is providing the initial 5000W due to passthru on the 12V. If 5000W is exceeded, the 12V provides additional 5000W via powerassist.

"both outputs" = AC out 1 and AC out 2 to L1 and L2, respectively? AC out 2 is ONLY active when the unit is provided with ac input power. When it is active, it is connected to AC out 1 via a relay, so it is effectively just another place to pick up AC out 1.

When inverting, L2 will be dead.



If joining L1 and L2, N is your limiter. Even if only using 20A on L1 and 30A on L2, there's 50A on N.



The Quattro can only draw from one or the other AC inputs, not both. You should set the AC input current limit for each input based on the source.



On a true split phase system, N only carries the current based on leg imbalance. In the above example, 20A on L1 and 30A on L2 would result in only 10A on N. If L1 and L2 are both using 50A, then N carries 0A.



Yes.



5-10%?



This will be the behavior by default. If either quattro is fed AC, it passes through the AC to loads and charges with any excess current if needed.

Feeding the 12V with 48V inverter will force the 12V to pass power from the 48V and charge with any surplus.
.


I can't envision a way to make that happen solely with the Victron hardware in the manner described. You could force the 12V to "ignore ac input" and force inverting when battery is in the peak voltage range.

Your post is essentially word soup, and it depends on the ability of the reader to translate the words to visuals. Vigorously recommend you sketch everything out. You appear to be a novice proposing to do aggressively typical things. it's worth your effort to sketch up a diagram.

Thanks. Couple things. The outputs on Quattro can both be on regardless using assistant relay. I have my out2 (L2) always on when SoC is >20%. I also believe many use both Quattro inputs at the same time not sure if this is needed or wanted in my situation.

I'm not a novice and understand a lot but don't understand how this coach and many others can run 6 120v AC units with a 20k 240V genny and not overload the neutral. Plus the TON of equipment they had.

I'll be creating a visio just want to get some more info before so I have a full understanding. There's just a lot of electrical safety rules that for some reason aren't universally applied. Like how a 20a ac unit can pull 50amps safely through a 20-30amp rated circuit and breaker. Or why I was able to run 200-250amps through a 150amp fuse for days and it not blow.

 

[sunshine_eggo]

Thanks. Couple things. The outputs on Quattro can both be on regardless using assistant relay. I have my out2 (L2) always on when SoC is >20%.

That works.

I also believe many use both Quattro inputs at the same time not sure if this is needed or wanted in my situation.

This is impossible. When a Quattro is supplied with AC input, passes through that signal. To use both inputs would require both inputs to be perfectly in sync. The Quattro can't force two sources to be in sync.

From the manual:

Two AC inputs; integrated switch-over system between shore voltage and generating set The Quattro features two AC inputs (AC-in-1 and AC-in-2) for connecting two independent voltage sources. For example, two generator sets, or a mains supply and a generator set. The Quattro automatically selects the input where voltage is present. If voltage is present on both inputs, the Quattro selects the AC-in-1 input, to which normally the generating set is connected.

I'm not a novice and understand a lot but don't understand how this coach and many others can run 6 120v AC units with a 20k 240V genny and not overload the neutral. Plus the TON of equipment they had.

If you weren't a novice, you would understand. The 240V system is split phase. The N only carries current based on the difference in L1 and L2.

Assume each A/C uses about 12A. 3 on one leg, 3 on the other. If 3 are running on 1 leg and none on the other, there is 36A on L1 and 36A on N. If all 6 units are running, there is 36A on L1 and 36A on L2 and 0A on N.

I'll be creating a visio just want to get some more info before so I have a full understanding. There's just a lot of electrical safety rules that for some reason aren't universally applied. Like how a 20a ac unit can pull 50amps safely through a 20-30amp rated circuit and breaker. Or why I was able to run 200-250amps through a 150amp fuse for days and it not blow.

If you were able to do what you claim, you are dealing with defective components.

 

[timselectric]

Everything eggo said.
And don't feed split-phase shore power/generator into this setup. Unless you really want to see the magic smoke.

 

[justinm001]

That works.



This is impossible. When a Quattro is supplied with AC input, passes through that signal. To use both inputs would require both inputs to be perfectly in sync. The Quattro can't force two sources to be in sync.

From the manual:

Two AC inputs; integrated switch-over system between shore voltage and generating set The Quattro features two AC inputs (AC-in-1 and AC-in-2) for connecting two independent voltage sources. For example, two generator sets, or a mains supply and a generator set. The Quattro automatically selects the input where voltage is present. If voltage is present on both inputs, the Quattro selects the AC-in-1 input, to which normally the generating set is connected.



If you weren't a novice, you would understand. The 240V system is split phase. The N only carries current based on the difference in L1 and L2.

Assume each A/C uses about 12A. 3 on one leg, 3 on the other. If 3 are running on 1 leg and none on the other, there is 36A on L1 and 36A on N. If all 6 units are running, there is 36A on L1 and 36A on L2 and 0A on N.



If you were able to do what you claim, you are dealing with defective components.

So the generator is outputting in a split phase which means I can pull 50amp+ loads from each leg to L1 on each inverters and then only the imbalance will be over neutral, never over 50amps? I'm only limited by the gauge of wire.

If so then if the inverters are in passthru mode wouldn't it just be passing through that same split phase power?

If on inverter or boostassist modes I get the power wouldn't be in phase and if 48v inverter output is connected to 12v input for the 12v outputs they'll need their own Neutral so instead of 4/3 I need 2x4/2.

I'm a bit confused on Quattros actual amp limit as it's documentation says 2x100a maximum feed through current. But the aux output is 50amp.

I'm not too concerned as 99% of the time I'll never need 50amps total but that 1% of the time when I've been gone a week and it's 140 degrees inside the coach I'd like the option to kick all 6 ACs on and cool quickly then go back to having 1 or 2 max running. This would be on genny since it'd drain my batteries very quickly and I have an auto transfer switch already installed that I bypassed so plan B would be to reconfigure for all to go through ATS and genny have a separate connection for inverters in2 then have it set to charge only mode.

This actually might make the most sense as it gives me an additional redundancy so I could run 1 inverter, 2 inverters, or just genny.

I'm not sure what you mean as defective, I'm assuming the fuses. I had Victron MEGA fuses in my lynx all 150amp as my larger ones didn't come. I had one from the alternator to the lynx then another from lynx to inverter. The alternator was pumping over 2000w 120v per the wakespeed and the inverter was running over 2000w some of the power was going/coming from solar and/or batteries but both the alternator and inverter were on their own 150amp fusses as was the solar and batteries (on Lynx shunt using CNN 150amp fuse). I did finally blow the alternator fuse or at least burn it a bit and show I pulled over 3000w. I believe the alternator fuse still worked. These were Victron branded from invertersrus off amazon. I replaced them with 300amp fuses now and shunt with 500amp.

Prior to me buying the coach it was a commercial coach who spared no expense building the 120v electrical system. It's a custom coach built specifically to train and showcase how to use jail equipment like ATMs and other machines they had installed in the coach.

 

[sunshine_eggo]

So the generator is outputting in a split phase which means I can pull 50amp+ loads from each leg to L1 on each inverters and then only the imbalance will be over neutral, never over 50amps? I'm only limited by the gauge of wire.

That's how split phase works. Each leg is in the opposite direction, so N only handles any imbalance between legs:

L1 is going CW
L2 is going CW
As both return on N, it's in the opposite direction.

If so then if the inverters are in passthru mode wouldn't it just be passing through that same split phase power?

No. You can only connect one leg to the inverter. They are 120VAC. Period. No exceptions. No magic. Your 20kW generator is 10kW/leg. If you're not using both legs, it's only a 10kW generator.

If on inverter or boostassist modes I get the power wouldn't be in phase and if 48v inverter output is connected to 12v input for the 12v outputs they'll need their own Neutral so instead of 4/3 I need 2x4/2.

Need to see this in a sketch.

I'm a bit confused on Quattros actual amp limit as it's documentation says 2x100a maximum feed through current.

Each input has a 100A ATS on it, so you can pass through 12,000W and boost with 5000W. Wiring should be sized for 142A, or AC input limit should be set accordingly.

But the aux output is 50amp.

That's AC-out-2. The relay that connects AC-out-2 to AC-out-11 when engaged is limited to 50A. This implies you have less surge capability on AC-out-2.

I'm not too concerned as 99% of the time I'll never need 50amps total but that 1% of the time when I've been gone a week and it's 140 degrees inside the coach I'd like the option to kick all 6 ACs on and cool quickly then go back to having 1 or 2 max running. This would be on genny since it'd drain my batteries very quickly and I have an auto transfer switch already installed that I bypassed so plan B would be to reconfigure for all to go through ATS and genny have a separate connection for inverters in2 then have it set to charge only mode.

6 A/C is possible, but the inverter output wires must be sized for passthrough and power assist, and you would be at the absolute limit of one leg of the generator. Recommend you read the manual on installation, 4.3.

AC-out-1 (see appendix A, maximum torque: 7 Nm) The AC output cable can be connected directly to the terminal block "AC-out". With its PowerAssist feature the Quattro can add up to 5kVA (that is 5.000 / 120 = 42A) to the output during periods of peak power requirement. Together with a maximum input current of 100A this means that the output can supply up to 100 + 42 = 142A. An earth leakage circuit breaker and a fuse or circuit breaker rated to support the expected load must be included in series with the output, and cable cross-section must be sized accordingly. The maximum rating of the fuse or circuit breaker is 142A.

This actually might make the most sense as it gives me an additional redundancy so I could run 1 inverter, 2 inverters, or just genny.

I'm not sure what you mean as defective, I'm assuming the fuses. I had Victron MEGA fuses in my lynx all 150amp as my larger ones didn't come. I had one from the alternator to the lynx then another from lynx to inverter. The alternator was pumping over 2000w 120v per the wakespeed and the inverter was running over 2000w some of the power was going/coming from solar and/or batteries but both the alternator and inverter were on their own 150amp fusses as was the solar and batteries (on Lynx shunt using CNN 150amp fuse). I did finally blow the alternator fuse or at least burn it a bit and show I pulled over 3000w. I believe the alternator fuse still worked. These were Victron branded from invertersrus off amazon. I replaced them with 300amp fuses now and shunt with 500amp.

Either the components are not performing as they should, or you are mistaken on the current they were experiencing. With both loads and charging, net current may be in play, not total.

 

[justinm001]

No. You can only connect one leg to the inverter. They are 120VAC. Period. No exceptions. No magic. Your 20kW generator is 10kW/leg. If you're not using both legs, it's only a 10kW generator

Totally get this but if I have genny setup so each leg goes to in1 of each inverter then out to out1 on each inverter then to the panel on its separate leg will it still be in a split phase, since it's just passing through the inverter? Or do the inverters affect this even if they're just passing thru?

The idea is instead of plugging one inverter to the other I can organize each circuit to the right inverter based on use.

I'm still debating if I should just spend the 6k or so and replace it all with 48v then a couple grand on a 48v alternator. Setup as split phase and then bill have a buddy plug for others.

I lost all faith in relying on any of these fuses. It was 2 separate fuses on at the same time connected to the Lynx and all was wired correctly. The WS500 was reporting the wattage through CAN to the cerbo and the cerbo was showing the inverter load as well. This was all on the load side so irrelevant of battery since on load side.

 

[timselectric]

Totally get this but if I have genny setup so each leg goes to in1 of each inverter then out to out1 on each inverter then to the panel on its separate leg will it still be in a split phase, since it's just passing through the inverter? Or do the inverters affect this even if they're just passing thru?

Absolutely not.
These inverters can not operate in a split-phase fashion. If you connect them to a split-phase system. You are introducing 240v across the two inverters.

 

[justinm001]

Absolutely not.
These inverters can not operate in a split-phase fashion. If you connect them to a split-phase system. You are introducing 240v across the two inverters.

Even if they're just passing through and not inverting or boosting power? Why wouldn't they just be in a bypass state and be connecting the in to the out at this point? Is this Victron specific or all inverters?

I thought as long as the voltage and hertz were within spec the inverters just pass along the power. I don't believe I've see it alter output voltages or hertz like I've seen with enterprise UPS systems for servers.

 

[timselectric]

Even if they're just passing through and not inverting or boosting power? Why wouldn't they just be in a bypass state and be connecting the in to the out at this point? Is this Victron specific or all inverters?

I thought as long as the voltage and hertz were within spec the inverters just pass along the power. I don't believe I've see it alter output voltages or hertz like I've seen with enterprise UPS systems for servers.

Even when passing power through. The system is still connected to that power.

 

[justinm001]

Even when passing power through. The system is still connected to that power.

That power.. you mean the split phase from the genny? I think you're confused here. If I have wire 4/3 that can handle 100amps from genny to 2 separate inverters where both share the neutral, one had red and other is black. Either the inverter will be pulling the loads or they'll be passing through the loads. Either way only the neutral will handle the unbalanced load.

If the inverter is inverting the power then it wouldn't be split phase and I'd be limited to the neutral 100amps. Which is fine because I have a pair of 5000w inverters so can't even make 100amps combined.

If for some reason the inverter is pulling the loads and then also outputting the loads on genny power and its not just a bypass then I risk the loads being out of phase and overloading the neutral when operating over 100amps. If this is the case I simply would need to add another neutral and ground wires from the 2nd inverter neutral to the circuit breaker so each inverter has a neutral and ground properly rated.

Again nothing is 240v here and all loads are 120v just spread through both legs designed to be able to pull 200amps (20kW) through 100amp cable using split phase setup.

 

[timselectric]

Again nothing is 240v here and all loads are 120v just spread through both legs designed to be able to pull 200amps (20kW) through 100amp cable using split phase setup.

The generator is 240v.
Split-phase is 240/120v. You can NOT connect 240v across two units that are not designed to be placed in Split-phase configuration.

 

[justinm001]

The generator is 240v.
Split-phase is 240/120v. You can NOT connect 240v across two units that are not designed to be placed in Split-phase configuration.

Why? I currently have 1 inverter plugged into 1 leg of the genny and then the neutral and ground, leaving red unplugged. When I add a 2nd inverter, why can't I just plug the red wire into L1 input then share the neutral and ground?

At a minimum I can as long as both inverters have input limits less than the neutral wire gauge. Or if they're in passthru it should pass the Split-phase through the inverters to the circuit and back.

My question is just does passthru simply bypass the inverter or does it alter the power in a way it could become out of phase?

Although it's possible I'm completely misunderstanding split-phase and 240v setups. But even with Eggos great help above it's reinforcing my ideas that split phase are just 2 separate 120v legs 180deg so they can use neutral to share the unbalanced load.

And just to be clear this would be 2 separate circuits red and black where the inverters hot wires are not tied together in any way, just shared neutral and grounds. We're just talking about when the genny is on so inverters are bypassing the power through the circuit

 

[timselectric]

my ideas that split phase are just 2 separate 120v legs 180deg so they can use neutral to share the unbalanced load.

Split-phase is 240v single phase with a midpoint tap (neutral).
Not 180 deg difference.
The unbalanced load is the only part that is 120v.
All balanced loads are carried by the 240v.

 

[justinm001]

Split-phase is 240v single phase with a midpoint tap (neutral).
Not 180 deg difference.
The unbalanced load is the only part that is 120v.
All balanced loads are carried by the 240v.

Are you saying that Eggo and everyone else is incorrect and that 240v is not just 2 120V legs traveling in opposite directions/180 degree difference? Like his image above that I just repasted?

My question is about where is the load when the Victron inverters are in passthru/bypass? Is the load at the Inverter closing this circuit, opening another circuit at the output, or is it passed through the inverter and the load is at the device plugged into the outlet?

 

[timselectric]

Are you saying that Eggo and everyone else is incorrect and that 240v is not just 2 120V legs traveling in opposite directions/180 degree difference? Like his image above that I just repasted?

I'm saying that
1. it's not 180 degrees from each other. It's single phase, so that would be impossible.
2. The drawing doesn't say that.
3. Eggo didn't say that.
4. And whoever you are calling "everyone else" , is wrong.

I'm trying to keep you from making two big blue paperweights. But if you are dead set on doing so. Please record it and post it in https://diysolarforum.com/forums/up-in-smoke-learn-from-my-mistake.83/

 

[justinm001]

I'm saying that
1. it's not 180 degrees from each other. It's single phase, so that would be impossible.
2. The drawing doesn't say that.
3. Eggo didn't say that.
4. And whoever you are calling "everyone else" , is wrong.

I'm trying to keep you from making two big blue paperweights. But if you are dead set on doing so. Please record it and post it in https://diysolarforum.com/forums/up-in-smoke-learn-from-my-mistake.83/

Please elaborate how the drawing isn't showing both legs out of phase with eachother ie traveling in the opposite direction.

Also please elaborate where exactly the issue lies and why I can't connect 2 separate inverters on 2 separate hot wires with a shared neutral and ground, creating 2 separate circuits, provided I account for the limitations of the shared neutral wire. Say I have 100amp wiring and limit each inverter to 50amps.

I value and appreciate you input and everyone else's I just don't accept when people say NO but don't explain why? I'm here to learn about limitations and how it works so I can develop the best system using the resources available.

My understanding is the inverter is either passing through the circuit to the load or its absorbing the load as it completes the circuit then creates a separate circuit from its output.

 

[sunshine_eggo]

Please elaborate how the drawing isn't showing both legs out of phase with eachother ie traveling in the opposite direction.

They are flowing in the same direction. They are just opposite on the neutral.

My understanding is the inverter is either passing through the circuit to the load or its absorbing the load as it completes the circuit then creates a separate circuit from its output.

Please explain this.

 

[timselectric]

Please elaborate how the drawing isn't showing both legs out of phase with eachother ie traveling in the opposite direction.

Look at the arrows showing the direction of current flowing.

Also please elaborate where exactly the issue lies and why I can't connect 2 separate inverters on 2 separate hot wires with a shared neutral and ground, creating 2 separate circuits,

Once you connect them to the generator. They are no longer separate. The 240v ties them together. They are not two separate hot wires. It's one 240v circuit.