GE dishwasher does not like running on 4400w inverter.

[PTA-Row]

I have a 48v 4400w Magnum MS4448PAE inverter with a bank of 8 L16 flooded lead acid batteries.
Plenty of power to run a dishwasher that only draws 900w but for some reason it throws a fault any time it tries to run off the inverter. If I turn the generator on, it’s fine.
I’m even using a appropriately sized UPS on it to try to clean up the power but some ripple seems to be getting my through that and tripping the power monitoring circuit in the dishwasher.
Does anyone know what it is that’s causing this? Or a practical workaround?

 

[Rednecktek]

Is it freaking out about it's grounding, i.e. GFI fault maybe? Sounds like you've got plenty of wattage headroom.

 

[RCinFLA]

MS4448PAE does not have a GFI. I don't know about your UPS.

Being its a dishwasher, it may be checking for continuity between its neutral and ground power plug connection for safety reasons.

If your neutral is not bonded to ground at inverter or via grid electrical breaker box then neutral is floating and when checked by dishwasher it finds it open, therefore refuses to operate.

Usually inverters like this one is supplied with neutral floating, expecting it to be bonded to ground at the electrical box.

 

[efficientPV]

I have a GE Profile dishwasher and it works fine on a 700W inverter.

 

[PTA-Row]

MS4448PAE does not have a GFI. I don't know about your UPS.

Being its a dishwasher, it may be checking for continuity between its neutral and ground power plug connection for safety reasons.

If your neutral is not bonded to ground at inverter or via grid electrical breaker box then neutral is floating and when checked by dishwasher it finds it open, therefore refuses to operate.

Usually inverters like this one is supplied with neutral floating, expecting it to be bonded to ground at the electrical box.

Good thought but my neutral and ground are bonded at the inverter. My system is grounded with a single ground rod from the distribution panel though. I wonder if insufficient grounding would cause an issue like this?
I’ve also heard that you’re supposed to ground at the inverter but I’m not sure why. I would do the work to change it if I thought it might help.

 

[RCinFLA]

You should avoid two separate grounding points. If ground is to distribution panel then inverter neutral should also be grounded in distribution panel. It is best to put inverter neutral wire into the distribution box neutral bus bar directly next to where the distribution neutral bus bar's ground strap connection is to distribution box case.

Inverter neutral and case ground should not be connected at inverter. If you do not have inverter neutral grounded in distribution panel and have neutral bonded at inverter case you might get some small current flow between inverter ground and distribution ground due to voltage drop across current carrying neutral wire from inverter and distribution box.

You can check the AC outlet for dishwasher. First check for any small AC voltage between its neutral (wider prong blade) and its ground prong. You need some AC loads on inverter to creat the problem of voltage between neutral and ground. Then check for continuity between its neutral and ground.

The inverter likely has some EMI bypass caps from its hot and neutral lines and its case so the inverter case needs to have its own ground wire brought to distribution box case.

 

[Shunt Czar]

I have a Magnum MS4024 24 volt 4 kw inverter that runs our dishwasher fine. I'm at my other house as I write this so I don't remember make or model except it is not a GE.

You use a UPS on the dishwasher? Not sure I understand that. Either the dishwasher is connected to your inverter or it isn't??
It seems from what you wrote: batteries to inverter to UPS to dishwasher. If so, take out the UPS.

 

[PTA-Row]

The UPS was to stabilize the power enough to use a generator. Previously it would error due to out of spec frequency and voltage just due to normal generator fluctuations.
I was hoping it would help with running it on the inverter but no luck.

 

[Shunt Czar]

And what happens if you connect the dishwasher directly to the inverter AC output? (bypass the UPS)

 

[PTA-Row]

It throws error codes just like it does now. It will also blink off and reset the timer sometimes so that it just runs perpetually.
I sent the dishwasher in for service at one point but on grid power it doesn’t have any problems.

 

[Shunt Czar]

Not sure what to tell you. I've got a Tektronix scope and the waveforms from
my two Magnums has always been totally clean. In a couple days I'll be at my
other ranch and can report on what brand the dishwasher is there. We bought
it in 2016.

Not exactly related but you can see some scope shots of my inverter
driving the surge on freezers at:

You can see scope shots at 8:28 and 14:10

 

[Desert_AIP]

Have you put a multimeter on the inverter output to verify the voltage and frequency?

 

[PTA-Row]

Yes, bother them multimeter and the inverter remote are saying the power is more stable with the inverter than the generator in both voltage and frequency. That’s what’s confusing to me.

 

[Desert_AIP]

And it's outputting 120VAC at 60Hz?

Then, as others mentioned above, you likely have a ground fault or dual bond somewhere.

What's the voltage reading between Ground and Neutral?
Is there continuity between ground and Neutral INSIDE the inverter?

 

[PTA-Row]

Thanks for the info. I checked the voltage between neutral and ground with a 14A load on another circuit and it was .44 just under the limit. I did switch the neutral -ground bonding to the distribution panel which made a slight difference but the dishwasher still won’t run on the inverter.