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iantull asked

Can I switch from MPPT PV Battery Charging to Grid at night

First off, I'm new to the Victron community so still learning all the tricks about setting up automation. I have an 75/15 MPPT that I use for charging my 12V batteries. These batteries are for running low amperage draw devices and normally this setup works great. On the MPPT I only have the PV's and Battery connected so there is nothing connected to the Load. My devices connect directly to the batteries. I also have this MPPT connected to a Pi running the Venus OS Large software, mainly to allow me to monitor the battery Voltage and PV Charger input remotely. What I want to do is to be able to somehow monitor, PV level, Time of day (night time), Battery voltage and then depending on the results of data be able to switch a grid powered battery charger on and obviously off again depending on the results of that data. The reason for this if I get many days of bad weather and not enough to keep the batteries charged, my devices fail to run. At the moment I monitor this manually and turn on my grid powered charger on and off remotely. Any suggestions would be appreciated.

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Alexandra answered ·

@iantull

.

The easiest way to do it is with a relay and SOC, where the relay switches/activates the mains charger power point.

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iantull avatar image
iantull answered ·

@Alexandra thanks for answering my question but as I said, I'm very new to all this, I do have a grid powered battery charger that I'm currently using to charge the batteries when there has not been enough from the PV's due to either night or cloudy days and I can easily setup a relay to switch this "power point".

As for setting this up, I'm assuming I use streetlight ? setup the SOC levels for both sunset and sunrise, set a time delay for both so there is no false positives, then connect my 12V relay for switching the "power point" to the "Load" output of the MPPT.

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Alexandra avatar image Alexandra ♦ commented ·
@iantull

Use the relay on the GX. You can set it for generator. The use the relay to drive the power point for the mains charger. I guess you could also loop it through the streetlight function.

But is may have some undesired effects like keeping the charger off during the day if PV is not quite enough anyway. Some experimentation may be needed.

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iantull answered ·

@Alexandra As I said, I have this 75/15 MPPT (bluetooth) connected to a Raspberry Pi running Venus OS Large software, via a VE Direct to USB cable. I don't see any Generator Relay switching available within that software configuration. Maybe I don't have the software configured correctly but will look further into the documentation to see what I can find.

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