Switch between split phase and single phase

3 hours ago, AquaticsLive said:

How hard is it to switch a GS 6k 12V inverter to single phase from split phase? 

I have been looking at my electrical setup and it may work out better if I make my new inverter a single phase inverter and use my old PJ as a split phase and make the two systems separate.  My rooftop AC is single phase about 2k Watts so that is pushing the one phase of the inverter pretty hard, I put the blower and some other loads on the other phase.  The balance of the loads is not equal though so thinking I may be better off using the new GS with single phase so it can handle it better.  I am using 12V I know that may come in to play with internal heat of the inverter, although don't worry about the power feeding it.

Basic steps:

• void inverter software warranty
• access the System Setup menu (CFG -> System -> System Setup), and set the inverter output voltage to 120v.  (Yes, the inverter can safely run here with no loads before the hardwire reconfiguration.  The same cannot be said for reconfiguring a single-phase inverter to split-phase!)
• Pop the lid, and reconfigure the transformer output leads.  NOTE: The chassis AC lines are only 10AWG; these will need doubled up to handle the doubled amperage.  If you're not using AC input, you can "borrow" a line from AC Input to double up both Hot and Neutral output.)

Obviously, I'm quite willing to help you via video call if necessary to make sure it's reconfigured properly 😉.

However, that being said...if you aren't having inverter heat issues in current split-phase config, then I don't think you'll have anything to gain by switching to single-phase (though you would lose the auto-switching AC input ability).  Transformer losses will be exactly the same regardless of the battery voltage spec (12 / 24 / 36 / 48v) or output configuration (single or split phase).  Same can't be said for the FETs though between the battery voltage options.

Yes, the transformer won't particularly like imbalanced loads--BUT only if you're exceeding 3kw/side.  Otherwise (quite unlike HF inverters), the inverter doesn't care about load balancing.  Even so, it'll probably be able to sustain 4kw on a single phase (no load on the other) without overheating, but that can't be guaranteed.

10 minutes ago, Sid Genetry Solar said:

Yes, the transformer won't particularly like imbalanced loads--BUT only if you're exceeding 3kw/side.

Thanks, then I won't worry about it.  I just didn't want to beat up the new inverter.  Well if it was better to go single I would bug Sean and ask him to switch my wiring to single phase before he builds it.  Sounds like I would loose more things than it would be worth.  Thanks for spending the time to explain that in such detail.

If you don't already have the inverter, it'd be part of the normal build/setup process--so not a problem at all.

I can't see much point in switching to 120v for any North America structure. Unless you're doing split-sync...

Maybe in a big RV... they probably don't do split-phase in those things.

Get the legs as balanced as possible. Might be worth considering switching to 240v AC - probably not a cheap solution, though... I think it would be more efficient though, which is always nice.

Its all setup with 240v AC as much as I can just the Rooftop Air conditioner's compressor is single phase so it only grabs from that one line making it not as balanced as I would like.  I have it setup in an ambulance converted to a work truck/RV I have all my tools in there and place to sleep when I am on the road. 

Silly me, when i said AC i meant changing the Air-Conditioning compressor to 240v. LOL. Horrible acronym to use on a forum like this.
That would likely require a new unit - so expensive. I don't suspect your unit has a dual-voltage motor, but you might look at the wiring diagram for it to see if it can be wired for 240v input. (could be possible if the unit is also sold in other countries)

So this is in an RV? Now i understand why it's a 120v unit... But the RV has split-phase wiring? Or have you customized the wiring?

Cause, if this is for an RV, and the RV was originally 120v-only, i'd have Sean change you to 120v. It'll be simpler and not confuse the hell out of people who may deal with it in the future.

By the way... pet peeve; split-phase is single phase - it's just two different legs on the same phase relative to a neutral. Two-phase isn't really a thing.

Also, excuse my ignorance - don't know how an ambulance is wired from the factory. I'd imagine there's some kind of inverter involved, but no idea if they'd do full-blown split-phase...

I tend to prefer keeping things as close to the way they'd come from the factory as possible, hence if it was 120v-only, i'd tend to want to keep it that way.

My rooftop AC is single phase about 2k Watts so that is pushing the one phase of the inverter pretty hard, I put the blower and some other loads on the other phase.  The balance of the loads is not equal though so thinking I may be better off using the new GS with single phase so it can handle it better.

I would  keep the GS 6kw  split-phase 240vac .     Use L1 for the 120vac  air conditioner  since it is less than 3000 watts   and  connect the other appliances  to L2 .    The PJ  inverter  can handle  any other loads if needed .             You  say    its all setup with 240v AC as much as I can just the Rooftop Air conditioner's compressor is single phase so it only grabs from that one line  ...   so make L1  that line .    

Thanks, then I won't worry about it.  I just didn't want to beat up the new inverter.  Well if it was better to go single I would bug Sean and ask him to switch ...  

NO do not tell Sean to switch  but  keep it  240vac  split-phase .   Later you can parallel another  240vac split-phase GS 6kw and  and run all your other 240vac tools on 12kw  parallel  mode  and  not have to watch the unbalanced line .    

On 8/16/2022 at 8:14 PM, dickson said:

Use L1 for the 120vac  air conditioner

That is how I have it setup now, so I will leave everything the same.  The PJ only has the one current sensor and its on L1 so that is where I put the main load so I can watch it.  The PJ handles it without issues, I may have been worrying too much about the new GS inverter coming.  Budget is tight so took me awhile to save up for a GS inverter just trying to think of anything i can do to prep for the swap.  Exciting to get a new one to be honest so may be doing a little more prep than needed.

On 8/16/2022 at 6:04 PM, NotMario said:

no idea if they'd do full-blown split-phase...

Yes it's setup real split phase 50 Amp from the Grumman Olson conversion which installed the ambulance package. Shore power is a twist lock SS2-50R and it has an Onan 6.5K split phase generator.  It has a 50 Amp panel and the Onan power switching station.  Way more than I will ever need, but super handy as a mobile power station lol. 

Very nice. I wish all RVs were done this way, the 240v is good for high amp appliances.

Keep it split phase. I think dickson is right-on. Just keep it on it's own leg. As long as the second leg won't overload, you're good.
While balance is always preferable, it's not the end of world if you have some imbalance.

If your PJ is working, your GS will easily do it. No sweat.

Haha.  GS has two current sensors (one on the input, the other on the output), and it measures TOTAL power on both the input and output (i.e. it can see loads on L1 as well as L2).  As well as being able to determine AC power direction from said sensors as well 😉.

The control board in the preorder inverters DOES have a port for balance detection.  Basically, it'd allow the inverter to measure "Neutral" current and see how out-of-balance a split-phase load is (a Sean request)--but I didn't include the actual current sensor in the manufacturing requirements, as it notably increases the cost for dubious benefit.  If there's a load balancing issue, you'd probably notice the inverter overheating at less than full load--and said load imbalance would be very easy to identify with a clamp ammeter.

17 hours ago, Sid Genetry Solar said:

load imbalance would be very easy to identify with a clamp ammeter.

I am always monitoring the loads just one of those things we do for fun I guess. 

Okay next question reading the manual the input power has the option of 120 or 240 both say I can keep split phase out.  I am thinking on the input side I think it may be better to go with 120V since when I plugin at a job site or camp sometimes there is only a 15 Amp 120V outlet.  My thought is that may work better to use the charge function when I am on the road an extended period of time.  Any downside to having it setup that way?  I don't plan to use ATS since my system is already setup with a manual switching box which I plan to keep setup.  I can add a 120V inlet port just for the inverter to make it a clean dedicated source.