jasonsele avatar image
jasonsele asked

Why does AC Input Current Limit reduce when assisting?

I have 2 Quattro 48/5000/70 setup in parallel. No virtual switches and no ESS. Running v501. I am currently connected to 30A shore power. Everything functions normally and I'm receiving roughly 3300W incoming with 250W AC load. The Input Current Limit shows 28.2A in the VRM(I have it set to 30A). When I turn on a heater the AC load increases to 1750w and the shore power drops by the same amount. The input current limit stays 28.2A and it continues to charge the batteries with the spare power. After several hours I'll check back and see that the batteries have drained unexpectedly. At this point the shore power usually shows 500-700W, the Input Current Limit is down to 14.6A, and the battery is being drained while in Assisting mode. For some reason it is limiting the AC Input Current even though it should stay at 28.2A because the batteries need charging and the power consumption is high. The weird part is that If I turn off the heater for 10 seconds and then turn it back on the Input Current Limit jumps back up to 28.2A, the shore power returns to normal, and the batteries begin charging again, Assisting mode turns off.

I determined that it triggers Power Assist mode when I have other loads that push it over the shore power current limit, which makes sense. However, once the loads are gone it stays in Assisting mode and eventually will drain the batteries. Only after shutting down ALL AC loads including my 1500 watt heater does it reset from Assisting back to normal. It's possible that when the Input Current Limit drops to 14.6 it needs the power consumption to drop below that before it releases Power Assist but even if that is true WHY does the Input Current Limit drop in the first place? Shouldn't it use all AC-in power regardless of Power Assist? Why doesn't the Input Current Limit return to 28.2A once Power Assist stops?

For clarification I have a 50A RV and have wired L1 shore power to Quattro #1 AC-In-2 and L2 shore power to Quattro #2 AC-In-2. I then feed Quattro #1 AC-Out-1 and Quattro #2 AC-Out-1 back to the RV transfer switch for 50A. Since I am currently connected to 30A shore power I run in parallel mode but would run in split phase when on 50A. I assume that it is assisting from Quattro #2 from battery when on heavy loads.

MultiPlus Quattro Inverter Chargerinverter current draw
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1 Answer
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi, thats due to the minimum power assist current.

If the unit has to power assist, since otherwise the total current drawn from the AC input would exceed the configured input current limit, it will always do that with a certain minimum inverter current.

There is a list of these currents in an excel file on -> firmware files -> ve.bus

All the best, Matthijs

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