Victron Multiplus II 48/10000/140 - powerassist with low shore power amps

DIY
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So I have an issue which I’m hoping we can overcome….

On our narrowboat we have installed a Multiplus II 48/10000/140 so we can charge our big lifepo4 batteries (16.1KWh Fogstar x3) and service our AC needs, unfortunately our marina supplies 6amp shore power which falls below the minimum requirement for the Multiplus to use PowerAssist (spec says 11amp minimum but when I try to set the max shore power amps I can get down to 8.4amps but no lower)

So I can turn off powerassist and run the inverter in inverter only mode ignoring the shore power AC In if I want which means all loads are serviced by the batteries, but what I’d really like to be able to do is always have shore power connected so it can trickle charge my batteries as we consume power from them and then, particularly overnight when AC load is low they will slowly charge back up ready for the next day.

I can’t use charger only mode as I still need the AC loads to be provided by the battery (things like the fridge and freezer but also there is a small mac mini that runs 24/7 too) I suppose we could via node-red or something switch it from inverter only to charge-only at say midnight and then back to inverter during the day? my understanding is with powerassist off we can set our max amps from shore power down to a safer level (say 5amps) so we don’t trip our shore power breaker (which we can’t reset as the electric boxes are locked)

would the kind of workflow I’m envisaging be doable? or is there another way to achieve what I want - the killer is the min amp requirement for shore power to have powerassist active… if I could drop it down to 5amp we’d be all good but victron have stripped me of that option with the min being 8.4amp…

We have Cerbo GX mk2, Victron Isolation Transformer (bringing in the shore power), Multiplus II 48/10000/140, MPPT controller, potential to charge from Arco Zeus Alternator (not all wired in yet), Power-In, Lynx Shunt and Distributor.

I was hoping this would be easier than it’s turning out to be because I hadn’t appreciated the floor in amps for powerassist being higher than the shore power amps available to us, also the inability to simply say ‘only use ac in to charge the batteries, don’t use it to power loads’ which would be handy for us :slight_smile: obviously we’d also need to be able to set the ac in max amps to 5amps too for that to work.

hoping for some wisdom from the group here to help us out in getting this set :slight_smile:

thanks muchly, in advance….

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Not sure there’s a simple solution for you that does what you want… :frowning:

I have a similar setup (but with a 16A shoreline feed), during the summer I can either leave shoreline plugged in (supplies AC loads, PowerAssist comes in if load exceeds shoreline capacity), in this case the MPPTs keep the batteries topped up (solar priority). Alternatively I can disconnect the shoreline (or use AC Ignore on the Quattro) and rely purely on solar power, which is fine during the summer when the boat is unoccupied but probably won’t keep up when it is.

With such a low current shoreline feed the first solution won’t work, and I guess you don’t have enough solar power for the second one… :frowning:

3

Well interestingly i updated the firmware to venus os large today as i was going to play with node-red and now i can set the shore current limit to 5.8amp and it stays - so if this right we should be fine… Going to test it this week and see what happens

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The other solution is to fit an ac charger that will take 6A input at max and leave that running permanently with the inverter on invert only without a connection to shore power.