Multiplus 3000/24 buzzing while charging even at low current

[eranrund]

Took some measurements over the weekend using my phone placed right next to the fan.
Ambient noise was 29dB. Charging at 3A was 35dB and went all the way up to 45dB at 15A. Fan was measured at 63dB.
Discharging was similar.
Its not excessively loud but I have had a bunch of inverters that were completely silent until the fan kicked in so this is still a big disappointment.

 

[sunshine_eggo]

Took some measurements over the weekend using my phone placed right next to the fan.
Ambient noise was 29dB. Charging at 3A was 35dB and went all the way up to 45dB at 15A. Fan was measured at 63dB.
Discharging was similar.
Its not excessively loud but I have had a bunch of inverters that were completely silent until the fan kicked in so this is still a big disappointment.

How many low frequency inverters have you owned? If you don't know the answer, how many have been as heavy as the Multiplus?

 

[RCinFLA]

Buzzing is the result of high current magnetic fields around some wiring. It can be anything from a transformer with unsecured winding cores, to incoming battery cable vibrating an untighted metal cable clamp.

I put my DC breakers in small metal disconnect box I got from Home depot. The small metal box's cover had just bent over metal loops to act as hinges on door so cover fit a little loosely. The door, in just the right position, would buzz due to the battery line 120 Hz ripple current surrounding magnetic field from sinewave inverter input cable current entering box to breakers.

Many inverters use adhesive blobs to secure wiring to prevent them from vibrating against something.

Trick is finding out what is buzzing then securing it mechanically with clamp, tie wrap or glue goop. You might try listening and poking around with a wooden dow stick to find out what is buzzing.

 

[eranrund]

Yeah, this might be a fixable problem by securing something, but I am not yet ready to void my warranty...

 

[cdsolar]

Multiplus II fan vibration and retrofit kit

I have heard/read reports of fan vibration noise in Multiplus II inverters. I just found this...There appears to be a retrofit kit available for those models affected, where firmware updates don't help. Some other options herein may or may not void your warranty....

diysolarforum.com

 

[AmpD]

What does the inverter sound like when it is sitting on something soft like a pair of boobs or a pile of dirty laundry?

“Hey honey I need you to lay right here while I plug this in…whomp, buzz slap”