question

@rvicev

A black start and a dead lock are two completely different things. I think there has been a bit of a mixup between the two condition here.

A deadlock is when the system needs the GX to start up, but the GX is not powered up.

A black start is when the system has switched off completely because there is no battery power left or batteries are shut down in the case if lithium. (The GX is also off at this point so I can see how the two can be confused)

It is best to always set the inverters/system to shut down before the batteries do. That way the GX which should be powering up from the batteries will have power all the time.

A totally dead (black start) system can only really be recovered if:-

1. The battery reaches the system restart voltage/SOC (hence for auto recover from black start they recommend at least one small mppt with panels). This can, when solar starts up, also power up the GX allowing a remote generator start as well if it is set up)

2. A generator is switched on, connected to AC1 with sufficient power to start up the system (unless of course you switch off all the loads)

@tom4x

Was already wondering about that. I wouldn´t be using the car battery - that´s why I will be having a power station .... A 12V to 48V charger is possible of course but tends to be expensive. With the power station I will be having a 12Vdc to 230 Vac converter anyway, that´s why I suggested to connect this to the AC IN of the MultiPlus. But with @Lifeingalicia and @Alexandra clarifications this appears not necessary.

@Alexandra

Thanks for your clarification - I should have used the phrase ¨black start¨ instead of ¨dead lock¨, and my question therefore relates to your point 2. ¨the sufficient power¨ of the generator .....

So if I set a minimum SoC of say 20% and the Multi stops because of not enough solar power coming in, then there is still some power left in the batteries and the GX device remains functional.

Once the sun is back, if I then temporarily switch of all loads and temporarily lower the minimum SoC setting - as @Lifeingalicia suggested, using the GX device the Multi comes back to life and therefore also the solar inverter. Nothing else needed.

Once the solar inverter is providing enough power and the SoC increases I can then gradually start activating the loads (and of course not forget to reset the minimum SoC to is previous value)

Right ?

@Alexandra

OK - if the GX device can´t do this, I agree that´s a bit of a fiddle, but remains an option.

If we forget the lowering of the minimum SoC option for a moment, back to my original question : if I hook up a power station with only ca 2A output to AC IN, and the Multi is configured to limit the power from AC IN to 2A, will that work ?

This may take a while of course, with only 2A coming in .....

@Alexandra

Thanks - food for thought !

According to the Victron ¨minimum shore current limits¨ spreadsheet there should be no lower limit, as long as you don´t use PowerAssist.

The power station I will be building anyway for other purposes, at lower cost (yes, Blueti etc are (too) expensive - a big one over here is > 2 K usd).

Your point about MPPT is absolutely valid, although you oversimplify it somewhat.

Local regulations require breakers, DC lightning protection (+breaker) etc per MPPT string, and if panels are at some distance this must be done at both ends (i.e. at the panel side as well as at the MPPT side). Panels for MPPT would go at the expense of panels for ac-coupling because of lack of space, etc. Also, I like simple systems = few components; going though hundreds of pages on this forum, the Victron web-site and manuals over the last 3 months has only made me more anxious to keep the system set-up as simple as possible .....

@Alexandra

We have been deviating a little from the original question, and re-reading the whole discussion there is something which strikes me as odd. In the MultiPlus manual I read :

3.OPERATION
3.1 On/Off/Charger Only Switch
.......

When the switch is switched to ‘charger only’, only the battery charger of the Multi will operate (if mains voltage is present). In this mode
input voltage also is switched through to the ‘AC out’ terminal.

........

To me that suggests that if I switch the Multi to ´charger only´ and I apply power to AC IN, then there is a microgrid on AC OUT1 and therefore the ac-coupled solar inverter can start again, thus supplying the necessary power to the Multi to charge the batteries to raise the SoC (to above re-start level), whereafter the Multi may be switched to ¨on¨ again.

I.e. the power would not have to come from the power source at AC IN (weak power station) ? If so, there will be no problem at all. Or doesn´t this work that way after the Multi has stopped based on low SoC ?