question

what suspect is that you are overloading the generator and thus the generators voltage is dropping , set the shgore power / grip amps limit to say 25 amps on each quattro, this then makes a 50 amp max draw that the quattros will take from the generator.

the quattros will reduce there charge rate to the batteries to hold the load to under 50 amps.

if you had a cerbo then it would automatically adjust each quattro, but as you don't mention that I am presuming you only have the quattros.

notew, once the generator is running and connected the line voltage is fully controled by the generators output, the quattros follow the generators output, and thus they do not control the line voltage, once the gen stops or is disconnected then the quattros control the line voltage's

9KW is 37.5 amps at 240 volts so I'm guessing the 50 amp current from the Quattros is overloading the generator.

Thank you. Some more information here. I do have a Cerbo attached to the system. The 50AMPs referenced above to combined between the two quattros (so each is set at 25 amps).

By my math, this is okay (please correct me if I'm missing something).

9kW / 120V = 75amps (so a total of 50amps should be OK)

The part that is strange to me is that if I bypass the quattro and feed the boat panel directly with a similar 50amp load, the voltage doesn't drop - which leads me to believe it's something with the Quattros.

Thanks!

In a split phase system, the current set in each Multi/Quattro is equal to the value set in Cerbo since the two units are essentially in series.

You should be setting the input current limit to 37.5 amps or less to avoid generator overload.

This is unlike a parallel system where the current produced by each unit adds, so the current set in each unit is divided by the number of parallel units from what is set in Cerbo.

@chrispendl

Sometimes ac Voltage readings aren't created equal. And genset power is a likely place to experience oddities. On a really tacky cap-regulated genset I've seen 15V (over 230V) difference between Victron (lower) and cheap multimeter/genset readings. Victron is said to be RMS and the others say nothing. Purists I guess would believe the Victron one, but I don't think it's really so important.

On the Victron website there's a research article on (quality) gensets, and the sinewaves recorded are eye-opening. On my own genset I can detect noise from a heater fan, but not when from a Multiplus's output.

But I've better things to do than worrying about it. I accept ac as never really perfect, and a little understanding helps me ignore what might excite others.

Quick update that resolved this issue. When I went into the configuration of the Quattros using VeConfig, the "weak AC" setting was enabled. Once I disabled that, the problem went away. In this situation, weak ac enabled for a generator that doesn't need it will cause it to drop voltage. Hopefully this is helpful to others.

I had the same issue with the same behaviors--even with a 20amp accept limit the voltage would sag to 110v on each leg, tripping the chargers off. Running a load at the same time (like AC) would decrease the sag and keep the charging on, though of course at a slower charge rate. Turning off weak AC fixed it. I'll inform the Northern Lights support function so they're aware of the fix.

Thanks @chrispendl !