So I installed a multiplus 2 2x120 into my rv with solar mppt and 2 230 ah lithium lifepo4 batteries.
I left my converter in because I wired in a transfer switch to use while batteries are not in rv.
When I unhook from shore power and turn my converter off by the multiplus starts to make an EXTREMELY loud noise. I installed this in front compartment of fifth wheel and I can hear the multiplus outside at the rear of the fifth wheel.
But when I turn my converter back on the noise basically stops.
Why would it be making such a loud noise with the converter off?
Can I leave the converter on all the time?
Any help would’ve greatly appreciated. Thanks.
If this is with the batteries disconnected then I would expect some kind of instability as the Victron inverter/chargers require a battery to stabilize the DC bus.
Victron inverter/chargers, especially the II series will hum while charging or inverting. The higher the current flow, the louder they will be. I can certainly hear my Multiplus I outside the RV in these conditions.
Also, make sure the converter is not fed by the output of the Multiplus or you will be in a power wasting loop: charger powers the Multi, Multi powers the charger.
It’s with the batteries connected and no loads applied. All lights off nothing on other than the basic dc loads that an rv uses
So no reason for it to be loud with no loads?
I have an ekrano gx. If my converter is pulling power would that be easy to spot? Would my ax loads jump way up?
Not clear why you left the converter installed if you have batteries and a Multiplus. Multiplus will essentially take the place of the charging function of the converter but do it better. Converting shore power to DC is unnecessary and inefficient at that point.
The Multiplus is not designe to run without batteries installed. This has been discussed at length in other places on this forum.
What kind of noise are you hearing? A hum or something else?
Usually, the converter will contribute to DC bus power in combination with solar and the Multi’s charger without any side effects as long as you don’t exceed your battery bank’s maximum charging current. This isn’t likely with as much battery as you have but I’d rule out the converter as a contributing factor by DISCONNECTING its output from the DC bus. Turning it off may be sufficient. If that eliminates the noise then there is some conflict between the Multi and the converter.
If you run your RV without batteries, make sure the Multi is switched off because running the Multi without batteries is known to cause issues such as an unstable voltage on the DC bus.
Where do you have the converter AC input connected?
As I mentioned above, if the converter is getting power from the Multi then it could be attempting to charge the battery which will result in the Multi outputting AC power to the converter. That’s an infinite loop that will drain your battery bank eventually.
You will see power into the Multi from shore power in the AC input tile, AC output power on the AC output tile. Any difference between these indicates power consumed or supplied by the Multi. A high difference indicates the Multi is working hard. If you have a shunt on the battery, you can also monitor battery power (either way) but that will be a combination of the Multi, converter, solar and loads.
When I first turn on my Multi, it will charge the battery bank with a fairly high current for a few seconds to a minute then taper off to trickle charge after that. So there is a brief time I hear a hum from it.
I’m going to try to explain this do bear with me.
I have everything ran into the lynx distributer.
Then from the lynx distributer I have a cable that runs to the side of my storage to a connection that runs to my main control panel.
I would guess that doing it that way it’s installed after the multiplus?
I had to reorder some cables that run from my shunt to ekrano do I have it taken apart right now. If I have enough sunlight I’ll try to get reinstalled tonight. And try this again.
the the nutty professor in me says I should sit this one out, and point you to your nearest electrician or dealer who could maybe help you diagnose this.
I got everything hooked back up and now it’s fine? I must have had something wrong the first time.
I thank you very much for trying to help but I think I got it all fixed. I’ll do more tests this weekend when I have time. But so far so good.
Again thank you
Hope all is well now, but if not, the only thing I can think of is that something was wrong in how the ground(s) are run. That includes both the neutral (white) and safety ground (green) wires. The MP should be the one handling the bonding of the two, if I understand how things work. Disconnecting from shore (mains) power should enable the bond, with a few seconds delay, so the timing of when the disconnect happens and when the loud hum appears could be diagnostic.
And if the converter is not isolated, that could complicate things too.
