question

svalvasori avatar image
svalvasori asked

Dynamic Current Limit and Negative AC Current?

This is a Multiplus 3000/120/50A on a boat with solar and 10kW generator.

My salon AC has an inrush of 65A and will not start on my generator (45A per leg). I thought perhaps dynamic current limit would help with this so I enabled dynamic current limit and at the same time disabled the virtual switch as I'm not using it, and did not enable any assistants.

The current limiter did not help, it seems it's response time is too slow and the generator cuts power before the peak inrush can be limited.

Since I did this a few days ago, I've seen multiple overloads with 50A shore power connected and not dropping out. The overloads seem to be caused by the multi trying to do power assist over and over again when the load is actually quite small (~12A-20A). I also see a large draw on the batteries from the power assist and a very odd negative AC input current.

I'm not sure if it's related, but I do have a coffee maker that causes the invertor to make a sound like a relay chatter; I've read this has something to do with triacs in the coffee maker and the way it regulates heat.

1630335804664.png


For now I've put those settings back to ensure it goes back to normal.

These are the settings when the problem existed.settings.TXT

Multiplus-II
1630335804664.png (64.2 KiB)
settings.txt (1.3 KiB)
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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

I have a Nespresso coffee maker that has caused those same issues in the past. It cycles the heater rapidly to maintain temperature and the Multi struggles to keep up. Recent Multi firmware versions seem to be better at tracking pulsed loads like this.

AC startup current is a common problem. You should look into a soft start (NOT hard start) for your unit. MicroAir EasyStart and SoftStartRV are the popular brands but there are others. MicroAir offers versions to suit both small and large air conditioners. I've got one on my RV AC and one on my home heat pump. The home unit allows my 7KVA Honda inverter generator to start the heat pump.

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