question

Alex Pescaru avatar image
Alex Pescaru asked

AC input control issue: battery conditions...

Hi developers,
@Guy Stewart (Victron Community Manager) , @mvader (Victron Energy)

It's me again, with another issue that I found on my Multi RS Solar system.
The configuration is like the one attached below and it happens as follows:

1. Battery reaching 14% and after 30 second the grid is connected and the battery is starting to charge.
2. Battery reaching 15% during charging and the grid is disconnected and the battery is starting to discharge.
3. Go to (1) and repeat indefinitely. See below the picture from VRM.

Now....

If I change the end condition "Disconnect AC input on" on anything else than "Absorption finished", for example "Bulk finished" or "Battery voltage", this is going normally... Also seen on the picture from VRM.

Is it possible that the "last state" being somewhere stored like "absorption finished", because the previous cycle was complete until the float state, to be read by the function that decides when to disconnect the grid and therefore decide to disconnect?
Maybe a "reset state" somewhere when "connect to grid" is performed?

Thank you!

repeat.jpg

screenshot-20240108-121909.jpg

bug reportMulti RS
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2 Answers
Thiemo van Engelen (Victron Energy staff) avatar image
Thiemo van Engelen (Victron Energy staff) answered ·

Hi @Alex Pescaru

After some investigation we can confirm that at the moment, the bulk and absorption disconnection does not work correctly when the Multi RS is connected and receiving the charging setpoints via a Venus or BMS. As this is not immediately trivial to solve, we can not say anything on when this will be fixed. So the advice, as you already found, is to disconnect on a voltage that is indeed slightly below the Pylontech end voltage.

Kind regards,

Thiemo van Engelen

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Alex Pescaru avatar image Alex Pescaru commented ·

Hi @Thiemo van Engelen (Victron Energy staff)

Thank you for getting back to me and explain what's happening.

Much appreciated!

Alex


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mondeoman avatar image mondeoman commented ·
@Thiemo van Engelen (Victron Energy staff) is there any way to disable charging from the grid, allow charging from PV only, supply the loads from the grid and then Disconnect AC Input when the SOC rises above 20% due to PV charging (i.e. keep battery at 15% until the sun comes up again)? Thanks!
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Alex Pescaru avatar image
Alex Pescaru answered ·

Hi developers,

Just a small follow up for this issue, since some time have passed...

Don't want to push it too much, but I believe, like other users have also said, that a simple option like "Disconnect on SOC" it will cover all other options.

Both "Bulk finished" and "Absorption finished" can be "simulated" with SOC. Because "Bulk finished" is SOC = aprox. 80% and "Absorption finished" is SOC = 100%.

So having a "Disconnect on SOC" will complement quite nice "Connect when SOC drops below" and no other option will be needed.

Can we hope something up until InterSolar in June 2024?

Thank you in advance

Alex

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Related Resources

Additional resources still need to be added for this topic

Mutli RS Solar Datasheet

Mutli RS Manual