I saw few mentions that this or that inverter works or doesn't work with cheap AVR generators. All inverters I saw manuals for (Voltronic clones mostly) claim acceptable frequency from 43Hz to at least 63Hz which is a very large range. I see no max THD mentioned anywhere.

Does anyone know how to predict a certain AVR generator will work with a certain inverter? Before I even knew about this problem I helped my friends build their tiny system with just 400W solar, single 12V 100ah battery, a 1kW all in one inverter and a 2-stroke petrol generator. They haven't had a problem with the generator until the carb clogged up and started surging. And that is both one of the cheapest inverters and generators I ever saw.

Now I've recently bought a new generator, but it will be a while until I can connect it to my system (but I only have 14 days to send it back if I find something I don't like) so I wonder if there is anything I can do to determine this in advance.

My generator is a Chinese diesel 9500W (same line of products as this, but with 195FE engine and 7500kW alternator). My inverters are Easun SMH-7k (similar to Voltronic Axpert MKS V) and Y&H 10.2K (also known as PowMR, perhaps Axpert King? I'm not sure). 

Perhaps test the Generator so long in idle and under differing loads to determine it's real frequency and Voltage fluctuations.
That in itself should give you a fair indication how close to the 50Hz and 230V it is/stays. From that test you would be able to determine it's suitability for  Inverters with tight tolerances. 

I suspect that the brands that lock onto the frequency of AC-in (e.g. all Voltronic models) have a fairly low tolerance for the rate of change of frequency. Possibly also the ate of change of voltage, relative to a clean sine wave of constant amplitude. When a mechanical generator that doesn't have an inverter gets a sudden load change, the engine's speed changes rapidly, and the firmware can't lock onto the frequency. When that happens, the inverter rejects the AC source (e.g. AC input icon flashes, indicating that it is detected, but is "out of spec").

Hi !

I am operating an Voltronic Axpert MAX E 11 K Duplex Inverter, connected to 3 pieces of Pylontec US 3000 Batteries (10 kwh netto capacity).

I charge the batteries on cloudy or snowy days with an Briggs & Stratton Promax 9000 generator (synchronos avr generator. 7 kva continous load).

Charging is only possible if attach an electric heater in parallel, and start charging at lowest current (2 A, 50 V) and increase it step by step.

I managed to raise charging power up to 4kW (80 A),but this was not stable for a longer time.

3kW was stable to charge several kwhs into the battery.

It is a pity, as the Charger would be capable of charging with up to 150 A.

For sure that is 7.5 kW, that's more than the generator can handle for longer time.

But it seems to be, that you need twice the generator power, you  intend to use for charging.

I have to try if it helps to raise voltage and frequency of the generator a little bit.

Maybe to set it to 52 Hz and 240V.

 

Gruß

 

Roland