New Victron 48 volt inverter not producing proper AC voltage

[reader2580]

I have a Victron Multiplus II 48 volt that is about 45 days old. It does not appear to be producing proper AC voltage. The voltage is 119 volts, but I wonder if the frequency is off. This is used in a motorhome. I have a power supply for my CPAP that is cool when used on generator power, but it gets hot when running on inverter power. Microwave also seems to do strange things on inverter power.

Any ideas here? My Fluke 177 meter does not appear to have a way to test frequency. I have monitored with Victron Connect on a PC and don't see any issues. I have talked to the vendor I bought from and received a little help.

I also have charging issues where the inverter will fault out when charging my SOK 48 volt batteries, but that is a separate issue I have been working with the vendor on. I have not yet built the special communications cable between my Cerbo GX and my SOK batteries.

 

[solarsimon]

What makes you think the frequency is off? What difference would it actually make?

 

[reader2580]

I think the frequency is off because my CPAP gets almost too hot to touch when running on inverter power and is cool to the touch when running on generator power. Voltage is fine so I suspect frequency. The rotating plate in my microwave doesn't seem to rotate smoothly on inverter power.

It makes a big difference if things are possibly getting wrecked by bad power. My CPAP stopped in the middle of the night twice while on inverter power. The power supply was quite hot and I had to unplug it and let it cool before the CPAP would work again.

 

[Charleswgibbs]

Is the multiplus connected to any ac input? Is there a chance there is dirty ac power getting passed through the mp?

 

[John Frum]

I think the frequency is off because my CPAP gets almost too hot to touch when running on inverter power and is cool to the touch when running on generator power. Voltage is fine so I suspect frequency. The rotating plate in my microwave doesn't seem to rotate smoothly on inverter power.

It makes a big difference if things are possibly getting wrecked by bad power. My CPAP stopped in the middle of the night twice while on inverter power. The power supply was quite hot and I had to unplug it and let it cool before the CPAP would work again.

This measures frequency https://www.amazon.ca/KINCREA-Electricity-Monitor-Voltage-Digital/dp/B07Q121ZQY
You might need an oscilloscope to see what is going on though.

 

[reader2580]

Is the multiplus connected to any ac input? Is there a chance there is dirty ac power getting passed through the mp?

It is connected to a generator, but this is with the generator off and the inverter producing the AC power. If the generator is running and the Multiplus is passing power through my CPAP power supply is nice and cool.

 

[UpNorthMan]

We have a small 48v 250w Victron Phoenix inverter. My wife's cpap plays havoc with the voltage output as well. It will jump +/_ 10 volts while using it. I believe the two units are fighting each other because of the nature of their high frequency inverter/converter. I believe both units try to adjust for various conditions and cause harmonics. You can really see it with my small inverter. I've had some success by changing the voltage. But ultimately I wired a cheep 12v cigarette lighter inverter with an extension cord for the cpap. Just my uneducated observations. It works for us.
Ed

 

[reader2580]

I figured out the issue. My meter will do frequency by pushing a button a couple of times. The inverter is putting out a solid 50 hz instead of 60 hz! No, it is not a European model and it puts out 119 volts. I am really hoping my refrigerator and microwave didn't get damaged by the low hertz. Laptop power supplies are often universal and should be fine with 50 hertz I believe.

I am hoping this is just a setting I can change with Victron Connect. I have not looked at Victron Connect since I discovered this.

 

[reader2580]

We have a small 48v 250w Victron Phoenix inverter. My wife's cpap plays havoc with the voltage output as well. It will jump +/_ 10 volts while using it. I believe the two units are fighting each other because of the nature of their high frequency inverter/converter. I believe both units try to adjust for various conditions and cause harmonics. You can really see it with my small inverter. I've had some success by changing the voltage. But ultimately I wired a cheep 12v cigarette lighter inverter with an extension cord for the cpap. Just my uneducated observations. It works for us.
Ed

Last year I had a Multiplus 24 volt and my CPAP was just fine. I changed to 48 volt this year because I wanted the SOK rack mount batteries that are 48 volt. The issue is that the inverter is producing 50 hertz instead of 60 hertz.

 

[Charleswgibbs]

Do you have the victron connect software? I believe you can change the output frequency on some multiplus units, not sure about yours specifically.

The pdf for the configuration software shows a drop down menu for output frequency so hopefully it's an easy fix

This article has a screen grab that shows the 50hz/60hz selection

Programming your Victron MultiPlus inverter charger with the VE Configure program - Part 2 - The Settings

 

[reader2580]

I have the software and was using it during my trip. I never thought to check the software for frequency settings and have not checked yet today as back home and on shore power right now. I didn't check the frequency while on the road as I couldn't figure out how to get my Fluke meter to show frequency while I was on the road. I thought frequency had to be the problem since voltage was right.

I'll look at the software to find the hertz setting later today.