Disable slave charger in parallel environment

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question

sheidler asked Mar 18, '22

Disable slave charger in parallel environment

Hello everybody

My Setup is as following:

5 Pylontech US3000C Batteries

1 Multiplus-II 48/5000/70 GX (GC disabled by unplugging power to GC-board)

1 Multiplus-II 48/5000/70

1 Cerbo GX

And a few other thing which are not important for my question

The setup should get placed into my RV. So grid power is sometime only secured by an 8A breaker. In single mode I can limit max AMP to 6.5A. But in parallel mode the lowest would be 12.2A which would kill grid power if more than 8A would be needed for charging.

What if I only connect the master to grid power and do not connect the slave to grid and disable the charging function of the slave.

Is this possible - well should be - but can I modify the input current limit afterwards.

I do need parallel mode as I want to use power from batteries/solar for my power consumption which could be more than 8kW - for example induction cooking and air condition...

Thanks for a few hints....

Kind regards

Stefan

Multiplus-II MultiPlus Quattro Inverter Charger multiplus in parallel

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Modifications Space

Node Red Space

Answer 1 · 2022-03-18T05:09:13Z

klim8skeptic answered · Mar 18, 2022 at 05:09 AM

You might be able to run 2 multiplus in series?

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Answer 2 · 2022-03-20T15:48:53Z

sheidler answered · Mar 20, 2022 at 03:48 PM

Thanks for the hint - looks like an solution....

Programming/Cabling such solution is possible. But could both Inverters be connected to the same output phase?

They are not synchronized like in parallel mode.

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Answer 3 · 2022-03-23T03:09:08Z

shaneyake answered · Mar 23, 2022 at 03:09 AM

Have you updated the firmware on your inverters?
It looks like I can set mine to 1A per inverter. Can you maybe post some screenshots of where you are seeing this limit?

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Answer 4 · 2022-03-23T09:05:40Z

sheidler answered · Mar 23, 2022 at 09:05 AM

Well there is no need for an screenshot as it is described in the manual that for the 48/5000/70 the minimum limit is 6A and this is doubled in parallel mode...

The setup to serial sounds interesting but of course there is no given wiring example. I did check the video given by klim8skeptic. But there is no further explanation.

And he is not using grid power. So at the end I do have no clue.

And yes all firmware of all of my devices are up to date.

But thanks anyway

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shaneyake commented · Mar 25, 2022 at 04:52 AM

No where here does it actually say it will double when in parallel.
I know the hardware under ESS mode is able to reduce the current to 0.045A
https://www.victronenergy.com/media/pg/MultiPlus-II_230V/en/configuration.html

It does state under
https://www.victronenergy.com/live/ve.bus:manual_parallel_and_three_phase_systems

"Setting an input current limit works differently when setting it on a remote control panel, for example a DMC or GX device. Then (a) only one value can be set by the user, not a different for each phase, and (b) the configured limit will be used as the total limit for each phase. Example, setting 30A in a three phase system of six units (two per phase), on a DMC or GX Device, results in a max input current limit of 30A per phase. The difference of both methods is due to the different use case of both ways of setting it: settings in VEConfigure are supposed to be fixed in the install and done be the installer, for example matching an installed generator. And the input current limit as set on the GX device is intended to be set by the end-user, for example on a yacht or in a motor home, and being able to set it depending on the actual shore connection - and ofcourse without having to do the maths of multiplying with the number of installed units on a phase.)"

So it would seem that you could set the limit on the GX and it should work down to 6A.
Have you tried it?

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screen-shot-2022-03-24-at-73958-pm.png (61.0 KiB)

Answer 5 · 2022-03-24T09:39:40Z

sheidler answered · Mar 24, 2022 at 09:39 AM

What about AC coupling. One Multiplus connected to grid power and both connected as Inverter to battery. The Multiplus not connected via VE.Bus to each other.

Ok the second one is not an PV Inverter System. But in principle should work as well. Both AC-OUT-1 from the Multiplus to an single phase breaker bus.

To make it a little bit clear attached an overview

page-1.png (363.8 KiB)

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shaneyake commented · Mar 24, 2022 at 11:38 PM

You can not connect the AC-OUT of 2 inverters without the VE.Bus cable and parallel config.

You can AC-Couple the 2 but this is not supported by Victron at all. You will need to wire Shore to Masters AC-IN and then Master AC-OUT to Slave AC-IN and then AC-OUT to Loads.
You could use ESS to set a grid setpoint at 1500W and just have both inverters in normal parallel.

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Herve RV Nizard shaneyake commented · Mar 25, 2022 at 12:41 AM

That s interesting. I had a similar situation I wanted to solve. So what you are saying is that Multi 2 becomes the main and supplies alone loads < 1500w. then "calls" ac in at 1500 ( from Multi 1) so both can supply up to 4 to 5 kva each .

but how would M2 REACT when having to supply close to 10 Kva alone ( in terms of AC Output)?

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shaneyake Herve RV Nizard commented · Mar 25, 2022 at 04:52 AM

It is always best to have the inverters in synchronized parallel where possible. This gives you the highest output and the least chance of problems.

But you can have them in series if you really want to. You need to set the current limit on the slave to around 17A, The Master handles most of the load until it is maxed out and then the slave picks up the rest. I run my system with ESS enabled and actually do balancing so the inverters are always under equal load but that is more complicated. You should be able to get close to 10kva but probably only around 8-9kva that way. Synchronized parallel will outperform series.

What is your situation?

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Answer 6 · 2022-03-24T22:37:41Z

sheidler answered · Mar 24, 2022 at 10:37 PM

updated overview

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