Victron Multiplus in Parallel

[Fuss]

This is really only interesting if you have one multi or multiplus already and then a few years later, decide to buy another...........
Victron units cannot be paralleled unless they are identical in hardware and also in software release, even though there is some leeway with the software release.
When paralleled, some flexibility and redundancy is lost and if any unit fails you could lose your shore or generator power as the AC is passing through the unit.

But there is a bit of a workaround that worked for me.....
I ended up using the multi as input into the multiplus... Both with their own remote panels so amps can be regulated... and a bypass switch possibility for the multiplus when on shore power.

This gave me the flexibility to use both chargers at the same time or individually...To be able to have up to (2x2.5kw) 5kw through the inverters if needed, a max of (2x70a) 140 charging amps and to be able to bypass the multiplus shore power management if on a stable shore power circuit.
This also gives a redundancy backup in case one of the units stops working.

This setup enabled me to use 2 inverters that are not the same with many of the benefits of the paralleled system with more redundancy and flexibility.

[CharlieJ]

I am very familiar with both the Multi and the Multi Plus and using them in parallel.

I ended up using the multi as input into the multiplus... Both with their own remote panels so amps can be regulated...

This lost me. Perhaps a one-line sketch would help.

[Fuss]

This works well if the installation basis for AC source is a 3 way selection of either shore power, generator or inverter.

The output from the switch goes into the AC input for the new multiplus.
So this means that shore power, generator and inverter have their AC amps supplemented by the new multiplus. Which is a great feature of the multiplus.

So, in the case of the original multi inverter (or any sine wave inverter) .... The AC output from the multi goes into the input on the multiplus (as the multiplus does not care what the input is, shore power, generator or inverter). The multiplus then supplements the amps if necessary.

The 2 remote panels enable control of the DC charging rates into the batteries as now you have 140a available instead of 70.

The other thing I would recommend is to have a bypass switch so the AC input can bypass the multiplus. This gives 2 advantages...
1- the AC relay in the multiplus has the possibility to be rested when on a strong shore power connection.
2- if the multiplus ever gets a techical problem then you will still have shore power/generator power. Without this bypass then your shore power/generator power will only be available if your multiplus is both on and functioning properly.

[Dockhead]

I think it is an excellent idea!

A weak point of the Multiplus is that, with all your AC running through it, you are really stuffed when (not if) it fails -- you lose all AC power on top of your charging and inverting capability

This happened to me. Mine was repaired under warranty, but I spent a total of three or four whole days (two of them two people) getting the unit out and shipping it, then putting it back in and installing it, due to awkward mounting position inside my engine space.

I don't think that it is really acceptable for such an expensive and such a mission-critical piece of hardware to be so failure-prone. I'm wondering if Mastervolt is more reliable? It's lighter, that's for sure.

The AC bypass switch is a good idea. I also have a backup battery charger on board now.

[goboatingnow]

I don't think that it is really acceptable for such an expensive and such a mission-critical piece of hardware to be so failure-prone. I'm wondering if Mastervolt is more reliable? It's lighter, that's for sure.

I used to sell Mastervolt, its about the same, in both these makes , you get unexplained premature failures that are difficult to accept, given the enormous price premiums.


Dave

[Dockhead]

Originally Posted by Fuss

This works well if the installation basis for AC source is a 3 way selection of either shore power, generator or inverter.

The output from the switch goes into the AC input for the new multiplus.
So this means that shore power, generator and inverter have their AC amps supplemented by the new multiplus. Which is a great feature of the multiplus.

So, in the case of the original multi inverter (or any sine wave inverter) .... The AC output from the multi goes into the input on the multiplus (as the multiplus does not care what the input is, shore power, generator or inverter). The multiplus then supplements the amps if necessary.

The 2 remote panels enable control of the DC charging rates into the batteries as now you have 140a available instead of 70.

The other thing I would recommend is to have a bypass switch so the AC input can bypass the multiplus. This gives 2 advantages...
1- the AC relay in the multiplus has the possibility to be rested when on a strong shore power connection.
2- if the multiplus ever gets a techical problem then you will still have shore power/generator power. Without this bypass then your shore power/generator power will only be available if your multiplus is both on and functioning properly.

You can also just pull both AC wires out of the Victron and connect them to each other with screw terminal blocks. That's what I did when mine failed. Saves some space on the instrument panel.

Reason 1 is good if you have the version of the Multiplus with a 16 amp transfer switch. I bought the 50 amp version since my genset produces more than 16 amps @ 240 volts.

[JonathanB]

I have a multiplus 1600 that I have yet to wire into my battery bank. I have an offer of a 1200 multi. Will I be able to use the1200 with the multiplus wired into the same battery bank. The only thing I can think I might need them both for is to drive the washing machine to just get it turning which requires a bit of a surge. I imagine for the majority of the time I will only be using one of them.

This set up its in a remote building with no mains supply. I was thinking of getting a small generator to boost the multiplus if required but the multi would be cheaper and give me an inverter backup should one fail.

[Emmalina]

I recently put a phoenix 2kw on my boat and a large solar array hoping to eliminate the need to start my gen-set. Is it feasible to get another 2kw phoenix and put it in parallel to get the start current I need? Its a half hp motor on the compressor I think and only draws 4a when running but the inverter just bombs when I try starting the compressor !! Thanks

[ebaugh]

Originally Posted by Emmalina

I recently put a phoenix 2kw on my boat and a large solar array hoping to eliminate the need to start my gen-set. Is it feasible to get another 2kw phoenix and put it in parallel to get the start current I need? Its a half hp motor on the compressor I think and only draws 4a when running but the inverter just bombs when I try starting the compressor !! Thanks

Probably assuming you have 220-240 VAC compressor. If 110-120VAC it should start on 2000 watt inverter.

Unless you have a huge battery bank, it won't run long though.

[rom]

I am considering the purchase of a second multiplus 12/3000/120 230VAC and found this old thread. I would like to know if others have setup theirs the way Fuss proposes. Any feedback ? I wonder which of the two solutions puts less stress on those equipments.