Onan QD output legs in parallel?

[Solar_Mann]

Anyone here had luck combining the 2 output legs on an onan QD generator? The specific unit in questions is an 8k 120v. Being an inverter type generator I'm skeptical on combining both output legs. Spoke with onan today, guy didn't sound too sure but said they could not be combined without causing an error code and shut down on the gen. Trying to do this to get it to play nice with a MPII 2x120 inverter. Don't want to risk damage to a $10k generator.

 

[seneysolar]

If its a 120V generator, what do you mean by combining both output legs? 120 single phase in gives you 120 single phase out.

The MP II 2X120 will take 120V in on Line 1 and then combine the 2 output legs for 2 lines of 120 in the same phase. This is not to be confused with split phase.

Refer to the wiring schematics at the bottom of page 1 of data sheet.
MP II 2x120 Datasheet

 

[Solar_Mann]

If its a 120V generator, what do you mean by combining both output legs? 120 single phase in gives you 120 single phase out.

The MP II 2X120 will take 120V in on Line 1 and then combine the 2 output legs for 2 lines of 120 in the same phase. This is not to be confused with split phase.

Refer to the wiring schematics at the bottom of page 1 of data sheet.
MP II 2x120 Datasheet

with 120v only generators the MPII only pulls power on Leg1. This generator has 2 output legs with a 35amp breaker on each but NOT 240v across the 2 legs like a split phase gen. This setup turns the 8k generator into a 4k unless the 2 output legs can be paralleled

 

[seneysolar]

with 120v only generators the MPII only pulls power on Leg1. This generator has 2 output legs with a 35amp breaker on each but NOT 240v across the 2 legs like a split phase gen. This setup turns the 8k generator into a 4k unless the 2 output legs can be paralleled

Ahh ok, you checked if the 2 output legs of the generator are the same phase? Use a voltmeter and go across L1 and L2. If they are the same phase, it will read 0.

Onan tech support should be able to tell you if they can be combined. Assuming its an RV generator? That would be common in the RV world to have a single phase panel split with 2 legs of 120. Also assuming the RV doesn't have any 240V loads?

Perhaps the question is can you use both legs into the inverter? I think battery charging would only be pulled from L1 but otherwise I would think it would be fine as its just pass through power. Thats a Question for Victron tech.

 

[Solar_Mann]

Ahh ok, you checked if the 2 output legs of the generator are the same phase? Use a voltmeter and go across L1 and L2. If they are the same phase, it will read 0.

Onan tech support should be able to tell you if they can be combined. Assuming its an RV generator? That would be common in the RV world to have a single phase panel split with 2 legs of 120. Also assuming the RV doesn't have any 240V loads?

Perhaps the question is can you use both legs into the inverter? I think battery charging would only be pulled from L1 but otherwise I would think it would be fine as its just pass through power. Thats a Question for Victron tech.

I have not put a meter across the 2 legs on this unit yet. I completely understand how that works on a traditional generator, but this being an inverter type generator I’m concerned.
Like my original posted, onan tech said they could not be combined but he sounded very unsure of his answer.

there are no questions for Victron here. It’s a well documented “issue” with the 2x120 series of inverters.

 

[seneysolar]

Like my original posted, onan tech said they could not be combined but he sounded very unsure of his answer.

Sometimes another call to tech support will get you a different guy that actually knows the product.

there are no questions for Victron here. It’s a well documented “issue” with the 2x120 series of inverters.

Victron has this documented? Using 2 single phase inputs from the same source?

Question, does the generator have 2 neutrals as well?

 

[Solar_Mann]

Sometimes another call to tech support will get you a different guy that actually knows the product.

Victron has this documented? Using 2 single phase inputs from the same source?

Question, does the generator have 2 neutrals as well?

the issue of L2 being ignored is well documented. I am going to shoot onan support an email. was hoping someone here had successfully done it. The gen itself might have 2 neutrals, I am not sure. i really only deal with the wiring once it gets to the transfer switch not directly at the gen.

 

[seneysolar]

the issue of L2 being ignored is well documented. I am going to shoot onan support an email. was hoping someone here had successfully done it. The gen itself might have 2 neutrals, I am not sure. i really only deal with the wiring once it gets to the transfer switch not directly at the gen.

In the onan 8k QD installation manual, their wire diagram indicates the (2) 35a breakers are split off from a single line. Same with the neutrals, the go back to a single line.

 

[OkieRVer]

I have the Q8000 as well. It has a 35 amp double pole breaker on the generator. There are two wires{one off of each breaker leg} going to the transfer switch. There are also two neutral wires going to the transfer switch, where they are both bonded to the neutral bar. Each hot leg measures 120v to neutral. Measuring across L1 and L2 you get 0.