I'm new - question LV6548 120VAC input to 240VAC output

[RaiderRC]

Hello,

I'm fairly new to this but have been a hobbyist for years. I also have some electrical engineering background. I'm in the process of setting up my first off-grid system for a full-time RV (5th wheel) boondocking setup and am looking for advice from the Prowse community. I have a plan that I think should work, but I'm seeking feedback in case there are any glaring issues. My main reason for posting is to find out about the LV6548 inverters.

Solar:
The entire roof as much as possible, taking off all the roof top AC/s removing generator and installing a dual zone split system.
Batteries:
2x 48v 100Ah rack mounted, can expand later
Inverters:
2x LV6548

The need is for full time live streaming with 2 PC's as well as being able to power an 11Kw instant hot water heater, welder, and compressor if needed. Obviously not all at the same time.

My main question here is, can I use a 120VAC input and still use the inverters as a 240VAC output?

The manual recommends


But what if my input power from an RV park or generator only provides 1 leg or a 30amp service.


I know that you can't connect L1 on the input to both units as it will damage the system.

Does anyone know if this method will work?

 

[BentleyJ]

Easiest solution is to purchase a stand alone 120V battery charger. This would allow you to charge batteries directly with 120V, 30A shore power or any kind of small, portable 120V generator.

Alternate would be 120V to 240V step up transformer but the down side of this is you are still relying on the inverters to charge the batteries. With a separate battery charger there are many more options to charge batteries and be able to connect an emergency inverter if the LV's fail or use a DCDC converter to at least operate the 12V appliances.

 

[RaiderRC]

Easiest solution is to purchase a stand alone 120V battery charger. This would allow you to charge batteries directly with 120V, 30A shore power or any kind of small, portable 120V generator.

Alternate would be 120V to 240V step up transformer but the down side of this is you are still relying on the inverters to charge the batteries. With a separate battery charger there are many more options to charge batteries and be able to connect an emergency inverter if the LV's fail or use a DCDC converter to at least operate the 12V appliances.

So just hooking up one inverter to shore power you don't think this would work?

 

[OffGridForGood]

The inverter can't charge battery and invert at the same time.
It charges the battery and passes through the inverter to run loads directly from your shore power. So if that shore power is not 120/240 the pass through will not be either.
Easier - as Bentley said, use a dedicated battery charger that can run from your 120 source, let the inverters run off battery during charging.

 

[Quattrohead]

So just hooking up one inverter to shore power you don't think this would work?

No it will not.

 

[Mason Parsons]

It sounds like you've got a cool project in the works for your RV setup! Using the LV6548 inverters with a 120VAC input for a 240VAC output should be possible, but it's always a good idea to double-check with the manufacturer or someone with experience in off-grid setups.

Your plan to use the entire roof for solar panels and the rack-mounted batteries sounds solid. Just make sure to consider the total power draw and capacity of your system to avoid overloading it when using multiple appliances simultaneously.

 

[Zwy]

So just hooking up one inverter to shore power you don't think this would work?

No, it will set a code on the unit turned on.

If you didn't need 240V, you could run a pair wired for 120V but you have some large items you want to run. You could have purchased split phase inverters that were 120V/240V output in one inverter. Then stack as many as needed to handle the loads. If you have already purchased the LV6548's, then run them in split phase and purchase something like the Chargeverter for times when at shore power or using a small inverter generator that is 120V.

 

[OffGridForGood]

2x 48v 100Ah rack mounted, can expand later
Inverters:
2x LV6548

The need is for full time live streaming with 2 PC's as well as being able to power an 11Kw instant hot water heater, welder, and compressor if needed. Obviously not all at the same time.

Two rack batteries = 10kWh ESS
the stand-by current for the two inverters will be 50-60W each x 24 hours = 2.64kWh a large chunk of the ESS capacity.
I expect you realize the battery is small "can expand later" however you may be limited what you can run until ESS is expanded. Then PV becomes the limiting factor.
The RV-mobile set ups all seem limited by roof area, for the PV input available. The idea of extra PV to overcome stand-by is tough in RV's.
The best fix to stand-by current power losses in a moble set up is equipment with lower stand-by like Victron, but this comes at a cost.
Maybe better to consider now, rather than after installation.

 

[RaiderRC]

Two rack batteries = 10kWh ESS
the stand-by current for the two inverters will be 50-60W each x 24 hours = 2.64kWh a large chunk of the ESS capacity.
I expect you realize the battery is small "can expand later" however you may be limited what you can run until ESS is expanded. Then PV becomes the limiting factor.
The RV-mobile set ups all seem limited by roof area, for the PV input available. The idea of extra PV to overcome stand-by is tough in RV's.
The best fix to stand-by current power losses in a moble set up is equipment with lower stand-by like Victron, but this comes at a cost.
Maybe better to consider now, rather than after installation.

I hate the standby power draw, but i feel these units are the most efficient. Was hoping to maybe keep one unit on and should power all the computer stuff but when I needed to draw higher power, I would turn the second unit on/off for AC/ welding/ hot water. I think the hot water is going to be a big problem.

For now going to keep the hot water heater but want to get off propane.

 

[RaiderRC]

It sounds like you've got a cool project in the works for your RV setup! Using the LV6548 inverters with a 120VAC input for a 240VAC output should be possible, but it's always a good idea to double-check with the manufacturer or someone with experience in off-grid setups.

Your plan to use the entire roof for solar panels and the rack-mounted batteries sounds solid. Just make sure to consider the total power draw and capacity of your system to avoid overloading it when using multiple appliances simultaneously.

Thanks, It's going to be an intresting year. The 120/240 AC optional input is killing me it seems like these LV6548s need 240 input in order to really use 240 output.

Some please correct me if that statement is wrong.

If I only used solar and batteries everything would be fine.

 

[Quattrohead]

Sorry to tell you it is 100% correct, if you are using them in single phase they can take a single phase input but if you are using them 2x for split phase they will need a split phase input or they will fault.

 

[OffGridForGood]

I hate the standby power draw, but i feel these units are the most efficient. Was hoping to maybe keep one unit on and should power all the computer stuff but when I needed to draw higher power, I would turn the second unit on/off for AC/ welding/ hot water.

I don't have the 6548 model, however using my 6048's I can't just turn one off, because in the parallel set up there are load sharing/ comms cables and the master unit is "expecting" other inverter units to be available, if I turn off one inverter the others auto shut down; Not sure if the 6548 operates similar but you will want to find out and be sure before building.

 

[RaiderRC]

Okay so re-thinking, when the LV6548s are in 240v mode I won't be able to use 120v? Is that correct?

 

[Zwy]

Okay so re-thinking, when the LV6548s are in 240v mode I won't be able to use 120v? Is that correct?

A pair of LV6548's run in 240V mode, will output 120V on each leg. The advantage is you don't need to worry about leg imbalance, each inverter can output 6500W on each 120V leg.

 

[RaiderRC]

A pair of LV6548's run in 240V mode, will output 120V on each leg. The advantage is you don't need to worry about leg imbalance, each inverter can output 6500W on each 120V leg.

Okay I guess I am getting tripped up on the charging circuits on these LV6548.

 

[Quattrohead]

Okay so re-thinking, when the LV6548s are in 240v mode I won't be able to use 120v? Is that correct?

Correct. They will fault due to missing input leg.
And no, you can't just wire the single 120v to both inverters because then one will be 180° out of phase and it will try and jump off the wall in a cloud of smoke.

 

[Zwy]

Okay I guess I am getting tripped up on the charging circuits on these LV6548.

Charging should not have anything to do with 240V/120V split phase operation.

I have to ask what experience you have with electrical? The reason for asking is to determine how much help you need before hooking anything up and causing an inverter failure or unsafe condition. Safety always come first and if you are unsure, don't be afraid to ask.

One LV6548 will output 120V. If you add another with the communication cable between the 2 LV6548's and change the settings to allow 240V split phase, you get not only 240V between the 2 hot legs of the inverters but also 120V on a single leg to neutral. With 240V, one leg is fed to 1/2 of a breaker panel and the other leg to the other 1/2. Neutral from each inverter can be combined using a Polaris type connector or a junction block, then ran to the neutral busbar.

You will need to determine if N-G bond is present under inverter power. This test is simple, all AC inputs and outputs disconnected, measure for continuity between N and G with the inverter off. If continuity is not present, then you will need to N-G bond in the electrical panel. If continuity is present on both inverters, then you will need to remove the bonding screw in one inverter or remove both bonding screws and bond N-G in the electrical panel. I run my LV6548's with a 3 pole double throw switch so neutral is broken and the bonding screw in one inverter. My LV6548's are the early version.

How old are the units and where did you purchase from? The high PV voltage model?

 

[RaiderRC]

Correct. They will fault due to missing input leg.
And no, you can't just wire the single 120v to both inverters because then one will be 180° out of phase and it will try and jump off the wall in a cloud of smoke.

Yes definitely aware I can't run the 110 leg to both thanks for clarification for anyone else that reads this. It will go up in

 

[RaiderRC]

Charging should not have anything to do with 240V/120V split phase operation.

I have to ask what experience you have with electrical? The reason for asking is to determine how much help you need before hooking anything up and causing an inverter failure or unsafe condition. Safety always come first and if you are unsure, don't be afraid to ask.

One LV6548 will output 120V. If you add another with the communication cable between the 2 LV6548's and change the settings to allow 240V split phase, you get not only 240V between the 2 hot legs of the inverters but also 120V on a single leg to neutral. With 240V, one leg is fed to 1/2 of a breaker panel and the other leg to the other 1/2. Neutral from each inverter can be combined using a Polaris type connector or a junction block, then ran to the neutral busbar.

You will need to determine if N-G bond is present under inverter power. This test is simple, all AC inputs and outputs disconnected, measure for continuity between N and G with the inverter off. If continuity is not present, then you will need to N-G bond in the electrical panel. If continuity is present on both inverters, then you will need to remove the bonding screw in one inverter or remove both bonding screws and bond N-G in the electrical panel. I run my LV6548's with a 3 pole double throw switch so neutral is broken and the bonding screw in one inverter. My LV6548's are the early version.

How old are the units and where did you purchase from? The high PV voltage model?

Appreciate the detailed. As far as my experience I've passed electrical home inspections as a home owner, added ac and 2nd sub panel, so I feel like I can follow the technical documentation pretty well.

My #13 post was a panic post

My biggest problem I'm trying to find out is using grid power into these inverters. RV parks have 30a and 50a lines. When I'm attached to a 50a circuit everything should be fine and dandy, it's when I run into a 30a line where things will get tricky with this setup.

So far I think, a fancy transfer switch is going to be my best option. Maybe with a secondary charger. Basically I'm always running the RV through the inverters with solar and battery. And the batterys would have a secondary charger when connected to 30a? Maybe?

I have not purchased the units yet as they seem to be plummeting in price. I just saw 2 EG3 refurb 6548 for $1700. Definitely aware the years play a significant factor in firmware as well as the N-G bonding.

I did watch Will's video about N-G bonding and that it should be connected in the main panel. Which leads me into making the RV a sub panel?

Getting the RV this weekend so hopefully will get to put my hands on and see what components I have to start with and what to actually modify. I know there is a Power Control System in it but will have to figure out where or if that will even be included in the system. Maybe around the transfer switch.

 

[Zwy]

Yes definitely aware I can't run the 110 leg to both thanks for clarification for anyone else that reads this. It will go up in

One can stack the LV6548's in parallel and not 240V, thus just one 120V leg with 13Kw capacity. On a 50A pedastal, one would need to determine if legs on in 240V split phase, most likely the pedastal would be just 2 120V legs in the same phase.

I see you have not purchased any units yet. I would not use the latest LV6548V versions in an RV due to the high idle consumption. Limited PV space on a RV combined with high idle consumption is not a great idea. Much of what the panels generate will be used to idle the inverters. You can install switches to turn the inverters off, I have one to switch off my Growatt in the truck camper but much of the truck camper runs off 12V. The LV6548V has been reported to use 130W at idle, take that times 2 comes to 250-260W. 10 hours is 2600W, 20 hours is 5200W and 24 hours is 6200W. If you have 2000W of panels on the roof, it takes 3 hours of peak sun just to cover that overhead. Watch TV for 3 hours and it takes 1/2 hour of peak sun for just the inverter, the loads are on top of that.

I think you might be better served with something like the Victron MultiPlus-II 2 x120V. Read the description here, (not promoting you purchase from this vendor) this inverter was designed for RV applications. https://invertersrus.com/product/vi...bpb2hYGKUZ1zBW-Amaaq-99p4f15Qhn0aAl5REALw_wcB Prices have come down and there is plenty of guidance on how to incorporate a Multiplus into an RV. Low idle consumption will help stretch the batteries before charging is needed.