diy solar

diy solar

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

Maybe these videos will help you understand split-phase.
I watched those and totally understand how it works but don't understand why I NEED them to be in a split-phase configuration or else itll blow up. I understand if I have them identical as a split phase i'll be able to maximize my wiring and able to utilize all 20kW but i'll never use close to that. At most ill use 12kW and thats for just a few minutes a couple times a year when its been sitting and I want all 6 ACs to cool it down quickly so I can start the genny and turn them all on one by one. Outside of that i'll be using 5kW MAX and just running off solar.

I'm just trying to understand my options and the limitations, not so much best practices. Nothing seems to explain how bypass mode works in inverters and its affect on a split-phase system. Also wanting verification that running them as separate circuits won't cause any issues as long as I'm under the limitation of the neutral.
 
Nothing seems to explain how bypass mode works in inverters and its affect on a split-phase system.
The inverters don't affect the split-phase system.
The split-phase system affects the inverters.
Those two inverters aren't designed to be used together in a split-phase configuration.
You can not connect them to a 240v circuit.
No matter what loads you connect to them. 240v will be running through the two units.
At best, they will just shut down and save themselves.
At worst, they will release the magic smoke.
 
I'd recommend you first fully document your AS BUILT system.
You mentioned in a post last week that the coach has been re-wired more than once. You cannot depend on anything being standardized at this point and you need an AS BUILT to design any replacement. 3.

Trust nothing and test and trace as much as possible.

It is common on large coaches, to divide the system in to Left side and Right side to make it easier to wire and to connect. I think you are assuming a lot here and the mistakes are very dangerous and expensive.
The comments regarding re-wiring around the ATS make me believe you could end up killing yourself or someone else based on your assumptions.

You need an electrician who understands mobile systems and bonding, that's not going to a regular residential guy who has a pop-up he uses during hunting season.

I am NOT implying you are not capable, but this is not the stuff you want to learn on as these are extremely expensive lessons and life/safety impacting.
 
I'd recommend you first fully document your AS BUILT system.
You mentioned in a post last week that the coach has been re-wired more than once. You cannot depend on anything being standardized at this point and you need an AS BUILT to design any replacement. 3.

Trust nothing and test and trace as much as possible.

It is common on large coaches, to divide the system in to Left side and Right side to make it easier to wire and to connect. I think you are assuming a lot here and the mistakes are very dangerous and expensive.
The comments regarding re-wiring around the ATS make me believe you could end up killing yourself or someone else based on your assumptions.

You need an electrician who understands mobile systems and bonding, that's not going to a regular residential guy who has a pop-up he uses during hunting season.

I am NOT implying you are not capable, but this is not the stuff you want to learn on as these are extremely expensive lessons and life/safety impacting.
My 12V was rewired to add a firefly integration system only by the coach builder who originally built the coach (Nashville Coach). The 120V systems are original as built by them. I believe I have all the schematics for the 120V system but regardless the 120V is wired and labeled all nice and neat with even the outlets themselves labeled saying which breaker they're on. It was a commercial coach so designed and documented so make their jobs easier when troubleshooting. The 12V is a mess and I've been clearing and identifying items as they come through. I don't have access to the firefly system or controls yet but its a work in progress as I go device by device and map it all out.

Generator and Shore go directly to an ATS built with schematics on the door. I bypassed the genny part of the ATS and ran a new line for genny to my existing Quattro and connected the shore to the quattro directly. It then goes out the inverter using Red and Black as out1 and out (both set always on) thru the Shore ATS relay into breaker panel1 then panel1 goes to breaker panel2. Each outlet has its own 20amp breaker and the AC units have their own 30amp breakers.

There are a couple of lines that have additional relays that the Firefly system controls for 120V. The Coach charge outlet, Air Compressor outlet, Water heater outlet, and a large 12V to 12V gen battery merge relay. These are in a separate panel behind my firefly panel with switches which I believe change the NC to NO option.

This coach is designed differently than production coaches as everything is overbuilt to be reliable and stable as its very important to be working and quickly repaired. All wiring and such is through conduit and properly labelled. Below is my actual coach when I bought it and how it was setup when GTL used the coach (they replaced it with a newer but identical coach).


I'm in the process of remodeling it and customizing to fit my needs. I'm a tech guy who runs multiple tech companies including those that house millions of dollars in compute equipment in datacenters so have a full understanding of power requirements, capacity and working with 120V, 230V and even 3 phase power systems. I'm just not well versed inside the electrical cabinets and mainly deal with the N+1 requirements and power limitations at the rack. Its why I'm interested in the how and why not just the yes or no.
 
The inverters don't affect the split-phase system.
The split-phase system affects the inverters.
Those two inverters aren't designed to be used together in a split-phase configuration.
You can not connect them to a 240v circuit.
No matter what loads you connect to them. 240v will be running through the two units.
At best, they will just shut down and save themselves.
At worst, they will release the magic smoke.

This is what I'm confused about. Below I currently have it setup as #1 with just 1 inverter. Why can't I run it like #2 and how would 240V be running through the 2 units? Compared to running it like #3 where it seems inefficient.

1685550417095.png
 
This is what I'm confused about. Below I currently have it setup as #1 with just 1 inverter. Why can't I run it like #2 and how would 240V be running through the 2 units? Compared to running it like #3 where it seems inefficient.

View attachment 151243
There's nothing wrong with any of those options. As they're wired separately to separate loads. (The only common connection is on the input)

But that's not what you described previously.
You were sharing the neutral. (Common connection on the output)
 
There's nothing wrong with any of those options. As they're wired separately to separate loads. (The only common connection is on the input)

But that's not what you described previously.
You were sharing the neutral. (Common connection on the output)

Ok good thats what I was thinking. But even something like this where the neutral is shared in the breaker panels would work though right?
1685555387039.png
 
No
These two (different) units cannot be connected to 240v.
This is the part i'm confused about as there isnt anything different other than a shared neutral buss bar and the 120v loads should need to return through its correct neutral to complete its circuit. I've watched a couple videos and other things where its been done without issue like the one below as he used 2 120v battery banks to power each leg without issue over a shared neutral buss. He even shows how the 240V shows anywhere from 0 to 240v depending on how out of phase it is at that time.
 
This is the part i'm confused about as there isnt anything different other than a shared neutral buss bar and the 120v loads should need to return through its correct neutral to complete its circuit. I've watched a couple videos and other things where its been done without issue like the one below as he used 2 120v battery banks to power each leg without issue over a shared neutral buss. He even shows how the 240V shows anywhere from 0 to 240v depending on how out of phase it is at that time.
As I stated before. Which got you on the track of using the two inverters this way. It's completely fine to use the 2 x 120v inverters to feed the two legs of your panel.
What's not safe, is to introduce 240v into the same system.
 
As I stated before. Which got you on the track of using the two inverters this way. It's completely fine to use the 2 x 120v inverters to feed the two legs of your panel.
What's not safe, is to introduce 240v into the same system.
I agree but I'm not seeing where any 240v is introduced into the system. It's the exact same image as before but using a shared neutral buss. This is the same thar basically every circuit panel is wired up. Can you circle where the 240v is or where the problem lies?
 
I agree but I'm not seeing where any 240v is introduced into the system. It's the exact same image as before but using a shared neutral buss. This is the same thar basically every circuit panel is wired up. Can you circle where the 240v is or where the problem lies?
Go back to the first video I posted.
When the neutral is disconnected. The loads on either side are operating in series with each other at 240v.
 
Go back to the first video I posted.
When the neutral is disconnected. The loads on either side are operating in series with each other at 240v.
The neutral would never be disconnected. Look at the image I sent, we'd either have a redundant neutral in a split-phase or 2 separate circuits sharing the neutral bus which my understanding this would be a multi-branch circuit something like the link below.

 
The neutral would never be disconnected. Look at the image I sent, we'd either have a redundant neutral in a split-phase or 2 separate circuits sharing the neutral bus which my understanding this would be a multi-branch circuit something like the link below.

I'm running out of ways to explain it.
It's not safe, for the reasons I explained.
At this point, All that I can do is wish you good luck.
 
Thanks his video below explains the situation much clearer. The open neutral isn't part of my scenario.

I'll update with a final visio and photos of how everything is installed. I'm thinking it might work better running one inverter into another as I don't think i'll ever have over 100amp load
 
The open neutral isn't part of my scenario.
My point wasn't that you could have an open neutral.
The point was that the balanced loads are running on 240v. Only the unbalanced loads are running on the neutral.
 
Here's what the AC panels and ATS looks like. There's 4AWG from genny to ATS and from ATS to panel1 and from panel1 to panel2. 6AWG from shore to inverter, from inverter output to ATS, and ATS genny to inverter in2 currently. The Shore connection is in the front of the coach right next to the inverter and battery.

when adding a 2nd inverter I see a few options.

#1 Dual inverters, Setup genny as in1 on both inverters with shore as in2 on 48V, setup 48V output to go to in2 on 12V. This will give me the ability to drain 48V batteries then drain 12V batteries and have genny charge both inverters. 48V will boost the 12V inverter power giving 10kW max (8kW for inductive loads) all on battery power... for about an hour draining both banks when maxxed out but will work to cool coach. Need to be careful of overloading the neutral and any voltage issues that might occur. If genny's on I should get up to 20kW available which is well over any use case... maybe more as they both could boost, depending on wire gauge to panels.

#2 reconnect ATS, Have shore go to 48V inverter input then output from 48V to the 12V inverter input, then output to ATS. Genny connected to ATS so when its running it has priority. This would allow me to use 20kW genny power so I can run all AC units then use inverter power when off. Genny won't charge batteries. Would limit shore/inverter power to 10kW which is plenty.

#3 separate circuits for separate inverters. Shore and genny red to inverter1 then shore and genny black to inverter2 both acting as ATS with old ATS disabled. This means if one battery bank is dead than that group of circuits is offline until it charges.
 

Attachments

  • 20230531_160631.jpg
    20230531_160631.jpg
    299.6 KB · Views: 3
  • 20230531_155144.jpg
    20230531_155144.jpg
    222 KB · Views: 3
  • 20230531_155059.jpg
    20230531_155059.jpg
    260.5 KB · Views: 3
So I have the system setup as #1 where I'm only using 1 leg of shore/gen and my 48v is feeding into my 12V. I figured this way I'll drain my 48v then it'll start draining my 12V. CerboGX and shunt and everything is setup on 48V so 12v has no comms yet (have spare smartshunt I'll install)

Problem is I can run 1 AC off inverter no problem but can't get a 2nd to work. It overloads my 12V battery causing the BMS to trip. I only have 1 12V EG4 rack battery connected. Both ACs have easystarts so shouldn't be an issue. With just 1 AC I'm running 2kw so 2 ACs should be 4kw max after the startup which is the limit for the 48V but the 2nd AC load isn't even touching the 48v inverter.

I have the 12V Quattro set for 100amps (max) from input1 so unless the AC is trying to pull 80amps it should be bypassing through. The 2nd AC is a furrion 15.5k showing 1720w and 20amp max has easystart built in and no LRA info I can find.

Is there any options with Victron where I can bypass or something? I have UPS mode enabled which might be the issue. Also powerassist set to 3.5 which I could lower
 
TL;DR

disable UPS mode on both inverters.
set powerassist to 2.0

--------------------------------------

Are you doing this purely on battery or generator or shore?

"#1 Dual inverters, Setup genny as in1 on both inverters with shore as in2 on 48V, setup 48V output to go to in2 on 12V. "

You say you've set 12V input1 to 100A, so you're doing this off genny/shore? If genny, yes, disable UPS mode. With UPS enabled, the inverter is more likely to fall to inverter mode to prevent a power interruption in case of genny fluctuation.

Power assist to 3.5 means the inverter is going to try to support 3.5X the overload to the AC. Leave at 2.0 default unless you find a reason not to. Your battery is only good for 200A or 3600W, so the 12V quattro can't deliver rated power and has no surge.
 
Purely on battery I can't get 2 ACs working but when on shore I'm able to get a 2nd working. Shore is only 15amps and plugged into 48V so not sure why it would make a difference. This is just a couple tests so not 100% accurate. I'd love to get a 3rd AC working. My 50amp shore cord end broke and when I attempted to use it I could feel a shock on the side of the coach (whole thing is stainless steel). So we're down to 15amp until tomorrow.

I want UPS function for at least 1 inverter as I don't want power loss when plugging/unplugging. Maybe leave on 48v but off 12v? Although if it switches from the 48v to the 12v it'll turn things off then on... right?

The powerassist is the one I'm confused about. If I generally run 20amps shore and my SOK 48v is 100a that'll give me 9600w so if set to 3.5 it'll let me boost it 7500w plus the 2400w shore so 10kw. Which is perfect as that's about the max I'll ever want to use when not on 50amp or genny
 
I turned off my 12V inverter and wired it to bypass that one completely disconnected shore was able to have all 3 ACs running pulling over 5000w with the overload light blinking but still worked. I turned off 1 and plugged in 20a shore and able to have all 3 working without overloading inverter 2.27kw from shore and 3k inverting.

48v inverter has had powerassist set to the default 2.0. I'm going to leave it like this for the weekend and see if any issues. The 12V has lights and water pump so hopefully it'll last a couple days. It has a huge alternator and I have to go somewhere tomorrow so that'll help. I have a battery jump pack and a couple little lithium chargers I could use too.

1 AC seems to only maintain temps and takes 2 or 3 to lower it. This depends on the outside temp and sun. The coach is like half windows so the sun really beats in.
 
Purely on battery I can't get 2 ACs working but when on shore I'm able to get a 2nd working. Shore is only 15amps and plugged into 48V so not sure why it would make a difference. This is just a couple tests so not 100% accurate. I'd love to get a 3rd AC working. My 50amp shore cord end broke and when I attempted to use it I could feel a shock on the side of the coach (whole thing is stainless steel). So we're down to 15amp until tomorrow.

I want UPS function for at least 1 inverter as I don't want power loss when plugging/unplugging. Maybe leave on 48v but off 12v? Although if it switches from the 48v to the 12v it'll turn things off then on... right?

UPS function is a timing and sensitivity thing. It seeks to prevent a potential issue. It just changes the threshold of where the inverter takes over from the incoming power.

Disabling it will not cause loss of power. When I shut my generator off, the inverter takes over, and I see nothing more than a slight blip as the. The important part is that while I'm mucking with things, my wife's experience in the trailer is completely unaffected.

The powerassist is the one I'm confused about. If I generally run 20amps shore and my SOK 48v is 100a that'll give me 9600w so if set to 3.5 it'll let me boost it 7500w plus the 2400w shore so 10kw. Which is perfect as that's about the max I'll ever want to use when not on 50amp or genny

I don't follow your numbers at all.

Power assist works based on the AC input limit. If set to 20A, that's when power assist triggers. The factor determines how much of the deficiency is borne by the inverter vs. AC input.

2.0 means if the inverter anticipates a 1000W deficiency beyond 2400W (3400W total), it will supply 2000W of initial boost and then taper back to 1000W if the situation is stable, i.e., initially, the inverter is supplying 2000W, and shore is only supplying 1400W.

3.5 means if the inverter anticipates a 1000W deficiency, it will supply 3400W of initial boost unloading the AC input completely, and then taper back to 1000W if the situation is stable.

Higher numbers mean you use less of the AC input and put more strain on the inverter, i.e., it actually REDUCES your total power output for surges. The only reason you go above 2.0 is if the AC input is getting overloaded. If you want more total power, you actually want to approach 1.0.
 
UPS function is a timing and sensitivity thing. It seeks to prevent a potential issue. It just changes the threshold of where the inverter takes over from the incoming power.

Disabling it will not cause loss of power. When I shut my generator off, the inverter takes over, and I see nothing more than a slight blip as the. The important part is that while I'm mucking with things, my wife's experience in the trailer is completely unaffected.



I don't follow your numbers at all.

Power assist works based on the AC input limit. If set to 20A, that's when power assist triggers. The factor determines how much of the deficiency is borne by the inverter vs. AC input.

2.0 means if the inverter anticipates a 1000W deficiency beyond 2400W (3400W total), it will supply 2000W of initial boost and then taper back to 1000W if the situation is stable, i.e., initially, the inverter is supplying 2000W, and shore is only supplying 1400W.

3.5 means if the inverter anticipates a 1000W deficiency, it will supply 3400W of initial boost unloading the AC input completely, and then taper back to 1000W if the situation is stable.

Higher numbers mean you use less of the AC input and put more strain on the inverter, i.e., it actually REDUCES your total power output for surges. The only reason you go above 2.0 is if the AC input is getting overloaded. If you want more total power, you actually want to approach 1.0.
This makes a lot more sense and your explanation is exactlywhat im experiencing. What if there's a 4000w deficiency how does the powerassist work? I was under the assumption if power assist was set lower then it couldn't handle large boosts
 
This makes a lot more sense and your explanation is exactlywhat im experiencing. What if there's a 4000w deficiency how does the powerassist work?

Reality isn't as black and white as my description. It was intended to illustrate the concept. The "anticipated deficiency" is often more incremental. It can't predict the future, but it can compare the load to the pass through. Switching to Amps:

Running at 16A.. there's an increased demand of a total of 22A. 2.0 means the inverter will provide 4A rather than just the 2A. 3.5 means it will provide 7A instead of 2A. A big hard hit will behave as I describe earlier, but it will make those decisions very quickly, and the rate of change impacts it as well.

It sounds like your A/C units are all inverter-type, i.e., variable speed compressor with no surge, so I would not expect you to be having any issues associated with surge. When an LRA isn't listed, or it's blank, that typically means the run current is the peak.

I was under the assumption if power assist was set lower then it couldn't handle large boosts.

Nope. Backwards. Lower boost number means that there is a higher risk of overloading the AC input. Higher boost number means using less of the AC input thus reducing the total combined power.

Given that they are inverter-type, I would lower boost to 1.5 and only increase it if you overload shore.

Again, disable UPS as it may trigger disconnected from the AC input entirely, particularly with generator.
 
Reality isn't as black and white as my description. It was intended to illustrate the concept. The "anticipated deficiency" is often more incremental. It can't predict the future, but it can compare the load to the pass through. Switching to Amps:

Running at 16A.. there's an increased demand of a total of 22A. 2.0 means the inverter will provide 4A rather than just the 2A. 3.5 means it will provide 7A instead of 2A. A big hard hit will behave as I describe earlier, but it will make those decisions very quickly, and the rate of change impacts it as well.

It sounds like your A/C units are all inverter-type, i.e., variable speed compressor with no surge, so I would not expect you to be having any issues associated with surge. When an LRA isn't listed, or it's blank, that typically means the run current is the peak.



Nope. Backwards. Lower boost number means that
Awesome thanks for the tips. I'll lower it and disable ups then see what happens.

I have 2 dometic Penguins OEM, 2 furrion 15.5k new and 2 dometic Brisk2 evolutions. 1 furrion and both the brisk aren't working right now need thermostats. I have an easystart on one penguin too.
 

diy solar

diy solar
Back
Top