Victron inverters in parallel question

[Wild Goose]

Just wondering if anyone using a victron inverters in parallel can answer a question for me. Once they and paired, one master, one slave, do they both need to be on to and communicating with each other to work? With my loads I’d get by with just one probably 85% of the time, but thinking of going a second one for those times and to give redundancy, but can I just use one or the other a majority of the time then switch the second one on when I know I will have high loads, or once paired do they both need to be on together to work?
Thanks
Josh

[JayH]

Unfortunately, they both have to be on.

[smac999]

And if one fails both will stop. The good one would have to be disconnected from bad and reprogrammed as a single. So it does not add redundancy. Just to be aware.

If you want reducnancy only. Add a 2nd one with a transfer switch. But then you can’t use both if needed.

[Tillsbury]

I think the trick is to run them in series. One is effectively “shore power” to the other. This gives more efficiency as you’re only using one unless you go beyond its capacity, at which point the second one kicks in.

[Wild Goose]

All right, thanks for the replies. I thought it might be the case, I’ll change my plan a bit then, I’ll just have one feeding most of the boat outlets and cooktop, which will be 90% of the use, and have the oven on the other one with one or two outlets just in case. I don’t have any individual appliance that will need the capacity of the inverters in parallel so should work ok. Thanks for your answers

[waterman46]

Originally Posted by Tillsbury

I think the trick is to run them in series. One is effectively “shore power” to the other. This gives more efficiency as you’re only using one unless you go beyond its capacity, at which point the second one kicks in.

Interesting but is that possible? The first inverter is taking 12V and converting it to 120VAC. Now you want to put that output 120VAC into a second inverter? .. where?



They both need 12V input, so that means they have to be in parallel I think.


I would use two inverters, with the output of each connected to a different set of AC circuits. You can easily figure out the loads, then just divide the AC bus as required, such that it is very unlikely you would be able to exceed the inverter output for that set of circuits.

[Nico Domino]

I would not run any supply in series, you double the voltages fixed amps. In parallel, you double the output( w) and your voltage if fixed .
On top of that , converting DC to AC in 2 different units you may and up with different phases on the AC and this will cause all sorts of happiness.

[Tillsbury]

Originally Posted by waterman46

Interesting but is that possible? The first inverter is taking 12V and converting it to 120VAC. Now you want to put that output 120VAC into a second inverter? .. where?



They both need 12V input, so that means they have to be in parallel I think.


I would use two inverters, with the output of each connected to a different set of AC circuits. You can easily figure out the loads, then just divide the AC bus as required, such that it is very unlikely you would be able to exceed the inverter output for that set of circuits.

No, Victron inverters are usually attached to shore power, so they have AC in as well as AC out (and, of course, they have DC in and usually DC out too to act as a battery charger). They can run in "power assist" mode, which supplies some inverted current to top up the amount being drawn from the shore power supply if you want more. For example, my 240V shore supply is 16A, and the inverter can step in if required to add more power by taking it from the batteries and adding it to the shore supply.

Imagine one normal inverter running, providing up to 16A from batteries. Now send the AC output of this inverter to a second inverter. The second inverter believes that it's getting shore power. It can pass this straight through to the AC system on the boat, or if you need more power it can add extra from its inverter (connected to the same batteries).

You can disable this secondary inverter at any time from the control panel should you not need more than 16A (3.5kW, approx). You can enable it to provide a total of up to 32A (7kW) to the boat when you need it.

[smac999]

Originally Posted by Tillsbury

No, Victron inverters are usually attached to shore power, so they have AC in as well as AC out (and, of course, they have DC in and usually DC out too to act as a battery charger). They can run in "power assist" mode, which supplies some inverted current to top up the amount being drawn from the shore power supply if you want more. For example, my 240V shore supply is 16A, and the inverter can step in if required to add more power by taking it from the batteries and adding it to the shore supply.

Imagine one normal inverter running, providing up to 16A from batteries. Now send the AC output of this inverter to a second inverter. The second inverter believes that it's getting shore power. It can pass this straight through to the AC system on the boat, or if you need more power it can add extra from its inverter (connected to the same batteries).

You can disable this secondary inverter at any time from the control panel should you not need more than 16A (3.5kW, approx). You can enable it to provide a total of up to 32A (7kW) to the boat when you need it.

How do you stop it from charging the batteries? The one passing through would be charging the batteries. As the first one drained them to power the charger. Yiu can’t disable the charger and still have ac passthrough on a victron.

[swampbush]

You can disable charging using ve direct and then run the inverter in charge or inverter mode. Works better if you disable UPS as well. I leave my 1600va easyplus on invert and turn on the 3000 for bigger loads. Takes about 20 seconds to sync after turning on the bigger inverter.

[Dockhead]

Originally Posted by waterman46

Interesting but is that possible? The first inverter is taking 12V and converting it to 120VAC. Now you want to put that output 120VAC into a second inverter? .. where?

They both need 12V input, so that means they have to be in parallel I think.. . ..

No, besides inverting DC to AC power, these things also pass AC power through themselves, inverting additional DC power to supplement the AC power supply as needed. This function is called Power Boost. So this idea of series installation should work ok.

Originally Posted by Nico Domino

I would not run any supply in series, you double the voltages fixed amps. In parallel, you double the output( w) and your voltage if fixed .
On top of that , converting DC to AC in 2 different units you may and up with different phases on the AC and this will cause all sorts of happiness.

No indeed. Connecting these in series does not make an electrical series. The second one will boost the AC power provided by the first one using the Power Boost function. And it will synchronize the cycles just like it does with weak shore power or generator power.

[Dockhead]

Originally Posted by swampbush

You can disable charging using ve direct and then run the inverter in charge or inverter mode. Works better if you disable UPS as well. I leave my 1600va easyplus on invert and turn on the 3000 for bigger loads. Takes about 20 seconds to sync after turning on the bigger inverter.

Very clever idea. Do you have some schematic of your system to be sure we are understanding you correctly?


My main question is how do you make the 3000 pass the power through? Mine won't pass any power through if it's turned off.

[swampbush]

Originally Posted by Dockhead

Very clever idea. Do you have some schematic of your system to be sure we are understanding you correctly?


My main question is how do you make the 3000 pass the power through? Mine won't pass any power through if it's turned off.

I don't have a schematic, still finishing and tweaking it. The 3000 is effectively a generator or shore power to the smaller easyplus 1600. Actual shore power feeds into the ac in of the 3000. AC1 out of the 3000 feeds into the ac in of the easyplus 1600. The easyplus can be on as an inverter but with charge disabled, or on as a charger with charge disabled. It won't pass through if off. The smaller victrons only use about 10 watts on standby. It stays on invert all the time. I will get a 240 volt freezer so I wanted to be able to keep it on. When I changed to LifePo4 batteries there was extra room in the battery compartment, so it seemed a shame not to have a bigger inverter available as well.
I fitted alarms using the inverter relays incase someone forgets to turn on the larger inverter.
I have considered using the generator start function to turn on the larger inverter but it takes time to sync and you lose the use of the multicontrol.

[Dockhead]

Originally Posted by swampbush

I don't have a schematic, still finishing and tweaking it. The 3000 is effectively a generator or shore power to the smaller easyplus 1600. Actual shore power feeds into the ac in of the 3000. AC1 out of the 3000 feeds into the ac in of the easyplus 1600. The easyplus can be on as an inverter but with charge disabled, or on as a charger with charge disabled. It won't pass through if off. The smaller victrons only use about 10 watts on standby. It stays on invert all the time. I will get a 240 volt freezer so I wanted to be able to keep it on. When I changed to LifePo4 batteries there was extra room in the battery compartment, so it seemed a shame not to have a bigger inverter available as well.
I fitted alarms using the inverter relays incase someone forgets to turn on the larger inverter.
I have considered using the generator start function to turn on the larger inverter but it takes time to sync and you lose the use of the multicontrol.

Clever! I have been wanting to add a second charger/inverter in my system but couldn't quite figure out the best way to do it. This looks promising.


So you leave the 3000 switched on but in battery charger mode? So it does not burn power in inverter standby but passes the power through. OK, I get it now. When you need inverter power from that too, you just switch over to "inverter on" with the multicontrol. And you disable the battery charger function in the smaller one using VE Bus. Right?


I like it

[swampbush]

Originally Posted by Dockhead

Clever! I have been wanting to add a second charger/inverter in my system but couldn't quite figure out the best way to do it. This looks promising.


So you leave the 3000 switched on but in battery charger mode? So it does not burn power in inverter standby but passes the power through. OK, I get it now. When you need inverter power from that too, you just switch over to "inverter on" with the multicontrol. And you disable the battery charger function in the smaller one using VE Bus. Right?


I like it

I usually leave the 3000 off at anchor, but on charge at a marina. I don't have a generator connected to it so it is usually off at anchor. I turn on the 3000 for any loads approaching the limit of the smaller unit, such as cooking on induction.