Running out of battery power

So I have so far avoided running out of battery power – my house has literally only been without power when somebody (usually Jaco) does electrical work.

But today I’ve had a power outage and with the weather in Gauteng what it has been the last two weeks, I started thinking that I probably should have plans if I do run out of battery power – especially since it will likely happen at 2:00 AM.

So couple of questions:

  1. Should I look at an option to hook up my old generator (a 5.5 kVa Ryobi) to the system and use it to charge the batteries? I have a Victron Multiplus 1 5000 Va with 3x Pylontech US3000’s. Ive read this MultiPlus Generator FAQ [Victron Energy] briefly, so I doubt my generator is of high enough quality to charge the batteries at full amps. And of course, it is not connected at the moment at all.

  2. At what point should I just shut down the whole system? 10% SOC? I usually let the Pylontechs go down to no more than 25% or 30%. I seem to recall that they will shut down by themselves at 8% but it sounds like a better plan to shut it down in a controlled fashion.

  3. What should I shut down? Just turn off the inverter on the front panel and let the batteries sit idle but continue running the VenusGX? And when the sun do start charging the batteries again, do I just turn on the inverter again (say at 20% SOC)?

  4. Do I switch back to Eskom for the time being or keep everything on the inverter until I either know the power is back on, or until the batteries have sufficient charge again? I have non-essentials showing me when Eskom is back on (oven clock).

With the Multi II 3k I have the battery will deplete up to 25% (ESS setting) and then it will just start using the utility power instead of the battery.
To be true with DVCC and my battery driver’s current management the discharge current will start limiting before it reach 25% and use utility power to supplement what is needed.
I’m not sure if your version does not have this option, but it is a set and forget. Only problem will be if the utility is not available during the night as it seems they are starting to do now. But then just set a higher min SOC

IF I have all the info, set SOC to say 30%, to have lights spare if Eskom fails, and switch back to Eskom …

Eskom is cheaper than a generator, more batteries …

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The battery will send a DCL=0 (discharge current limit) around the 10% point, if I recall, and that should cause the Multi to switch off on its own. If not, then 10% is still a good point to switch it off yourself.

If we assume that this will likely be a rare event, and given that the Multi will likely require all sorts of tweaks to accept the power, it’s probably good enough to just run from the generator in this case. I would just install another changeover switch, and a generator plug (the kind they use for caravans and sometimes welding machines), and on the rare occasion that it really gets that bad, just use the generator like the rest of the people in this country :slight_smile:

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Plonkster understood my concern - I already run with a minimum SOC of 20 to 30% during which the grid is available and all is well - ESS does its thing.

This is more a question as to what I do when there’s an extended power outtage and a bunch of clouds like there was the last two weeks in Pretoria.

So basically:

  • do I let it run down and switch off by itself?
  • do I switch it off myself at some point?
  • do I connect a generator and try and keep the batteries charged?

Obviously I will do demand side management as well - switch off more essentials such as freezers and fridges and PCs and TVs and lights as it gets lower too.

Turn off just the inverter with the rocker switch on the front, right?

Yes, I would just turn it off by the rocker switch. If the outage continues much longer, and you worry that the GX and the other stuff still connected to the battery is draining it too much, then you can open the (fused) DC disconnect to completely shut it down.