240 generator into two single phase120 all-in-one chargers?

[shanemgrey]

I have 2 of the LV6548 All-in-one units from MPP and I'm working out how to set up for use with the generator.

The genny can do 7000 watt continuous and has a 30amp 240volt output which is 4 wire and I assume is split phase.

The LV6548 units can each take a 120 single phase AC input, and each have a single phase AC output as well. They can be configured to work together in a split phase configuration for supplying loads. But can they accept power from the different legs of a split phase input?

In other words, can I run the single 4 wire connection from the genny into the shed, then split the hot wires so that one goes to one charger, and the other leg goes to the other charger?

Are there any issues that might pop up like one charger being turned off for some reason while the other one is pulling a full load to charge the batteries from the generator power?

The generator also has 2 of the 120v single phase 20a outputs, which I would guess (with low confidence) are connected to each of the legs of the 240 output. So I think it's ok to draw out of balance power from the 240 output as long as the 30 amps is respected on each leg. But I'm not sure.

Anyone here have more definitive answers for if it's ok to split a 240 genny output into 2 all in one charger/inverters?

For reference, the generator is a Champion Tri-fuel 100416 rated for 7000 watts on natural gas which is what I'm running.

 

[BentleyJ]

Supplying each Inverter AC input with 120V from opposite hot wires and neutral from your generator should work. I believe the LV6548 has max charge amperage settings that you can use to limit gen output to 50 -70%. The only issue you could possibly have is if the generator output is outside of what the Inverter considers "stable" power such as frequency or voltage. Especially if you plan on turning on or off large loads where the RPM sags momentarily.

 

[shanemgrey]

"Especially if you plan on turning on or off large loads where the RPM sags momentarily."

Is the LV6548 is inverting from battery while charging those batteries from the AC input?

Or does it supply the load more directly from the AC input when connected?

If it's coming from the battery, do demand surges affect the generator?

 

[Lt.Dan]

"Especially if you plan on turning on or off large loads where the RPM sags momentarily."

Is the LV6548 is inverting from battery while charging those batteries from the AC input?

Or does it supply the load more directly from the AC input when connected?

If it's coming from the battery, do demand surges affect the generator?

The LV6548 does not double invert. If you want it to charge the batteries, it has to use the generator to supply the loads simultaneously.

 

[welnat]

Shane, what is advantage to running 120/240 which is limited to 30 amps, when you could have 40 amps and give each inverter 120 at 20 amps?
Is there a reason you want to run off the 120/240 output vs the two normal 120v outlets? (it being twist lock connector is a good reason right there!)

 

[koppted]

Don't know if there is problem with that setup in particular. Champion does makes a plug that splits 240v/30a to two 120v/20a. (L14-30P to two 5-20R)

Amazon.com

If you want it to be plug and play you'd have to make your own cord with two 5-20p plugs hanging from your AC inputs to plug into the 5-20r receptacles for the Champion cord

 

[Supervstech]

Shane, what is advantage to running 120/240 which is limited to 30 amps, when you could have 40 amps and give each inverter 120 at 20 amps?
Is there a reason you want to run off the 120/240 output vs the two normal 120v outlets? (it being twist lock connector is a good reason right there!)

You do know that 30A 240V is more than two 120V 20A right?

 

[welnat]

Does he need all the power? Does he already have the 4 wire conductor? If the inverters want 120 and the generator has 2x120 outputs, that seems like a match to me. If there is ever an issue with one inverter it is pretty easy to disconnect one and still have the other going.

Sorry- saw your comment. Yes each 120v circuit will have 16 amps available and the 120/240 would have 24 amps on each leg.

Poster hasn't told us what battery nominal voltage is.

I see the lv6548 claims to be able to charge up to 120 amps. I'm guessing that is at a 12v nominal battery?

 

[shanemgrey]

The LV6548 will be charging two 48v nominal batteries with a total of 560ah capacity. It should be safe to charge to at least 280amps, and more sustainable to do so at about 112amps. So that's about 6000 watts at the charging voltage, more than the 5400watts two 20 amp conductors could supply.

The generator can sustain a max of 7000watts. I probably won't run it with that much constant load, but it would be nice to have the conductors wired up to be able to do so. 240 at 30amps is 7200watts.

Since the generator has to supply the household at the same time as charging, it's nice to have some overhead above the power being pushed to the batteries.

I'll need to do more research on how much to draw from the generator for charging, but I think having the 30amp conductors supplying both inverters is the best option as long as it won't cause issues.

 

[John Frum]

The LV6548 will be charging two 48v nominal batteries with a total of 560ah capacity. It should be safe to charge to at least 280amps, and more sustainable to do so at about 112amps. So that's about 6000 watts at the charging voltage, more than the 5400watts two 20 amp conductors could supply.

The generator can sustain a max of 7000watts. I probably won't run it with that much constant load, but it would be nice to have the conductors wired up to be able to do so. 240 at 30amps is 7200watts.

Since the generator has to supply the household at the same time as charging, it's nice to have some overhead above the power being pushed to the batteries.

I'll need to do more research on how much to draw from the generator for charging, but I think having the 30amp conductors supplying both inverters is the best option as long as it won't cause issues.

What is your strategy for handling the neutral/ground bond?
Are you expecting split phase output from the inverters, in inverter mode or bypass mode?

 

[shanemgrey]

I need to do more learning on grounding and neutral in general. My initial thought was that I'd split the ground and neutral in a box the generator is connected to, running distinct lines to each of the inverters so that each has 3 wires run from the box to the inverter. The hot wires would be 180 out of phase from the generator, but the others would be the same. But I need to confirm that this would be ok with more study.

It seems that it should be, considering the simple splitter extension cords out there.

I am configuring the inverters to do split phase to provide 2 legs of power to the house. I'm expecting to get the same split phase power when running the generator.

 

[John Frum]

I need to do more learning on grounding and neutral in general. My initial thought was that I'd split the ground and neutral in a box the generator is connected to, running distinct lines to each of the inverters so that each has 3 wires run from the box to the inverter. The hot wires would be 180 out of phase from the generator, but the others would be the same. But I need to confirm that this would be ok with more study.

It seems that it should be, considering the simple splitter extension cords out there.

I am configuring the inverters to do split phase to provide 2 legs of power to the house. I'm expecting to get the same split phase power when running the generator.

The problem is that while inverter is in inverter mode neutral and ground will be bonded in the inverter.
If that happens in both the inverters then you have mutiple neutral/ground bonds which is a "bad thing"TM
If the neutral/ground bond could be done at the panel and disabled at the inverters and at the generator I think you might have a safe setup.

 

[WYtreasure]

I need to do more learning on grounding and neutral in general. My initial thought was that I'd split the ground and neutral in a box the generator is connected to, running distinct lines to each of the inverters so that each has 3 wires run from the box to the inverter. The hot wires would be 180 out of phase from the generator, but the others would be the same. But I need to confirm that this would be ok with more study.

It seems that it should be, considering the simple splitter extension cords out there.

I am configuring the inverters to do split phase to provide 2 legs of power to the house. I'm expecting to get the same split phase power when running the generator.

I don't know but it sounds like there may be a reason to take video when it's switched on. ?‍
That way you'll know where the smoke came from first.

 

[koppted]

The problem is that while inverter is in inverter mode neutral and ground will be bonded in the inverter.
If that happens in both the inverters then you have mutiple neutral/ground bonds which is a "bad thing"TM
If the neutral/ground bond could be done at the panel and disabled at the inverters and at the generator I think you might have a safe setup.

I feel like manufacturers should just avoid any sort of neutral/ground bond in any mode. It just creates a lot of problems. N-G bond at the inverter is good in only one use case, and that is if you wire and extension to the AC-Out of the inverter. In other cases it just creates problems, With generators that already have and NG bond, and with Service entrance panels. It would be better if they left that N-G bond to the end user.

 

[John Frum]

I feel like manufacturers should just avoid any sort of neutral/ground bond in any mode. It just creates a lot of problems. N-G bond at the inverter is good in only one use case, and that is if you wire and extension to the AC-Out of the inverter. In other cases it just creates problems, With generators that already have and NG bond, and with Service entrance panels. It would be better if they left that N-G bond to the end user.

dynamic neutral/ground bond as in ul-458 is pretty much required for the mobile use case.
When connected to shore power the neutral/ground bond is upstream of the pedestal.
when in inverter mode it must be in the local domain there the automatic transfer switch has to dynamically switch it.

 

[shanemgrey]

What I'm doing seems like a very common use case.

• Two inverters configured for split phase (which is the standard for North America residential wiring.
• 48v battery
• Solar
• Generator backup with a standard 240v 30a RV style connection. L14-30 plug

That said, I expect this configuration would have a very commonly used wiring diagram, including how to handle ground and neutral at the various points.

I'm reading through Grounding Made Simpler by @FilterGuy. I'm finding it to be an excellent guide. Very clear and direct with explanations for how things work and why the recommendations make sense.

But given how common my setup probably is, maybe someone can point me to an exact wiring diagram I could use?

 

[John Frum]

Generator backup with a standard 240v 30a RV style connection. L14-30 plug

The plug is yet another complication.
A pedestal is almost certain going to have an up-stream bond, a generator may or may not be bonded.

 

[shanemgrey]

It seems the LV6548 switches the bond on when there is no AC input, and off when there is. The champion generator has the N-G always bonded, with ground also connecting to the frame.

 

[John Frum]

It seems the LV6548 switches the bond on when there is no AC input, and off when there is. The champion generator has the N-G always bonded, with ground also connecting to the frame.

If both of them switch the n/g bond, that is 2 bonds which is not good.

 

[koppted]

If both of them switch the n/g bond, that is 2 bonds which is not good.

That is precisely what I'm getting at. You have a situation here where you either have to modify the generator, or you have to find a way to modify the inverter. Leave NG bonds to the end user IMO.