Inverter/Charger - No AC IN

[JohnO]

Hey all - trying to figure out what is going on with our generator ... while out, we switched on to charge up the batteries ... however, when we start it up and select the generator the house ammeter fluctuates significantly almost like a sine wave ... it starts at around +13a, then begins to drop down to +2a (sometimes negative depending on the load). Also, when we look at the xantrex inverter/charger it shows no AC in. I'm working to trace wires for those connections, but thought I'd see if anyone has any ideas. Not sure why I'd see any positive amps at all on the house bank if the interter/charger was not getting AC In. Perplexing.

BTW - we have an Onan 8kw MDKD and Xantrex MS2000 Sine Wave Inverter/Charger.

Thanks in advance!

 

[STB]

Shut off all loads and, if possible, leave the generator putput switched away from the load. Put a meter on the generator output. What is the voltage? If you have a scope, what is the waveform?

Switch the power select over to the generator. Now how does the output look.

Not try a simple resistive load....an incandescent light, electric burner on low, hairdryer on low, etc. Be sure an inverter is in no way involved. How about now?

Try a heavier resistive load...still keep the inverter out of it... turn an electric burner up. Or a hair dryer on high. Or a resistive electric heater. How about now?

Now try a complex load. Maybe an AC. How about now?

Then try turning on a charger without an inverter, if you have one...how about now?

Finally do it again with the inverter-charger.

And then with a load on the outputnaide of the inverter.

St what point in this testing do things get weird?

 

[Bmarler]

To add, what happens on shore power?
You shouldn’t need to trace wires, (yet) just do a little preliminary testing like stb laid out for you. Panel instrumentation or a portable voltmeter would be helpful.

 

[Mischief Managed]

If the Onan 8kw MDKD genset does prove to be the culprit, and the voltage regulator is found to be the root cause, you can replace it with a generic regulator, AVRSX460 and perhaps some resistors for around 40 bucks in parts.

 

[CharlieJ]

The Xantrex will only qualify and accept incoming power within a specific frequency range. With a DMM, test the output frequency of the genset with no load. If it is outside of the qualified power frequency range, the inverter/charger will not accept it.

 

[JohnO]

Thanks all - this is really helpful info. Going to try the suggestions.