Hello,
I recently installed a Multiplus Compact 12/2000/80 in my sailboat and was disappointed to discover that it is generally very loud. I would really like to get to the bottom of this noise. It is not coming from the fans. Actually, I don't think I've ever had the fans turn on. I suspect it is a 60Hz hum from the toroidal transformer. I really just want it to be able to quietly pass through AC power 99% of the time. I would be OK with some noise when it is inverting or charging. But the noise is loud without using the inverter or charger whatsoever.
Below I will try to describe my set-up to the best of my ability. I welcome any clarification questions or tests I should try to gain more insight. I would really like to better understand what is causing this noise if it is a hardware, electrical, or software configuration. I find it really hard to believe that it is not possible to have some sort of configuration where the Multiplus is quiet. I have updated to the latest firmware version in Victron Connect.
On the AC side
My AC input is a 30A feed that goes to a breaker and then to the Multiplus. There is a Victron galvanic isolator on the ground before the Multiplus as well. AC output from the multiples goes to my AC panel main breaker and subsequently to a few circuits that power the various outlets on my boat.
On the DC side
The Multiplus is connected to my flooded lead-acid battery bank consisting of (2) 6V GC2 batteries in series.
The Multiplus hums excessively loudly in my opinion, especially for the confined spaces of a boat. I did not expect it to make so much noise. I can understand if the unit is inverting at a high load or charging at a high rate. However, the unit is loud outside of these two conditions. I have confirmed it still hums loudly when:
1. I disable charging in Victron Connect
2. I shut off the AC output breaker
3. I disable Power Assist in Victron Connect
4. I disable UPS function in Victron Connect
The only thing that remedies the hum is disconnecting the AC input breaker. Strangely, I've found that running a particular heater on full power can make the hum sound softer than it would with absolutely no AC load.
Typically, without any load, the hum comes and goes in cycles. There are periods of silence that fade to a medium hum for some time that gradually get louder before fading back to silence.
I've attached a recording of the noise taken from my cellphone 2 meters away to give you an idea.
New Recording 10.m4a
I would love to hear from other users of the Multiplus Compact 12/2000/80 about whether their units make a similar noise as well as any users who have suggestions that might get at the root cause and potential mitigation strategies.
Thanks!
