question

leander avatar image
leander asked

Protecting batteries when mains supply trips

Hi All,

We have a Victron Multiplus (24volt/3000VA/70 Amp). Our "mains" supply comes from a hydro-electric turbine system that trips frequently (once every three of four days). We have a battery back-up system that is connected to photovoltaic panels so that when the hydro trips our electricity supply smoothly switches to battery-sourced.


Our worry is that if we have a large load on (e.g. an emersion heater or electric heater) and we're not in the house when the hydro trips, the batteries will eventually be totally drained.

Is there a way of setting the Multiplus so that the electricity supply to the house will completely switch off when the hydro trips?...thus protecting the batteries.

Thank you.

MultiPlus Quattro Inverter ChargerCCGX Color Control
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The easiest way should be to connect the large loads to the AC-OUT 2.
With the standard settings the AC-OUT 2 is only powered as long as the AC-IN is available.
So you keep the UPS function for the other loads(+ you set a higher DC cut-off voltage to not discharge the batteries to deep).

OR

You switch the Multi into "charger only" Mode. In this mode the Multi will charge the batteries and pass through the mains to the loads. As soon as the mains fails the Multi will switch off.
But you will lose the UPS function for the other loads.

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leander avatar image
leander answered ·

Hi M. Lange,

Thank you very much for your very helpful reply. That's brilliant. I switched the Multi to "charger only" mode and lo and behold it worked! I had tried this before but there seems to be a delay before the "charger only" mode kicks in...and I had never waited long enough before.

The idea of using the AC-OUT 2 for the heavy loads would actually work very well for our immersion heater/water heating element as that is wired in separately in the consumer unit. Our Multi has a 16A transfer capacity so I think we would need to have the two neutral wires in the same neutral socket and the two ground wires in the same ground socket but the two live wires L1 and L2 each have their own socket. Is that correct?

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