AC500 Quiet Charging too often and not so quiet

I have an AC500 with a single B300 (not S) connected. It’s configured as a Customized UPS, settings as follows:
SoC 35-80%
Time control off
Grid Control on
Power Lifting off
Silent Charging on

Both AC and DC are switched on. The DC loads are three USB cables charging phones for maybe 15W total. On the AC outlets there’s a single switching power supply brick powering a small weather station for another 10W.

The AC500 appears to charge the B300 several times every day. I haven’t seen any logging options but guess we hear it 3 or 4 times each day.

Problem 1: It’s loud when charging. Much louder than our AC300. Does quiet charging do anything useful?
Problem 2: Why does it charge so frequently with the SoC set between 35-80%? I’ve yet to see it discharge below ~69% and it has definitely started charging when the B300 SoC is above 70%. Right now the largest loads are the inverter and fans while charging, so the behavior puzzles me.


@cyrnel 1. The charging power of AC500 is higher than that of AC300, and the fan will turn when the heat accumulates to the temperature. 2. Under the setting, AC500 will not charge when the SOC is not lower than 35%, please check the setting or take a short video and we can check the problem.

My previous report was incorrect in that the AC500 is not necessarily charging when the fan noise begins. I’ve seen it repeatedly now where the fan(s) start up at high speed when nothing is really happening besides AC and DC being switched on. Load is almost zero, with a single small switching power supply plugged into an AC outlet and one <5W USB device plugged in. Load on the LCD panel is 0W for both. Ambient temp is about 75F. When the fan(s) start there’s considerable heat coming from the left side of the AC500.

I wouldn’t mind if this were in a shed or basement but it’s in our house and the sound is noticeable several rooms away. Can you please request product engineering update the temperature monitoring code to run the fans at a lower rpm, starting at a lower temperature, to prevent the heat build-up and resulting high-speed fan use?


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@cyrnel I will check with our technician. If I have any update, I will let you know ASAP.