MPPT RS450 interrupts charging process at about 97%

Re-post from the DESS release thread:

My MPPT RS450/100 temporarily interrupts the charging process when the battery is near full.

I have a large pack so the Multi's are still charging 2kW at that time but the MPPT RS stops for a few minutes before continuing. Before and after that one stop, all is working fine. Either help charge the remaining % or invert.

So far, it takes about 5mins to recover. Ramping down the panels. Turning to -10W for a while. And firing everything up again.

Can not be sure but it seems to be related to the switch from bulk to absorption charging. For both AC-PV as well as DC-PV feed-in to grid is enabled. I'm using DVCC with 40kW of Pylontech packs.

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kevgermany ♦♦ commented · Apr 21 at 05:16 PM

Charge rate is dictated by the batteries. They also report SOC. And Pylontechs certainly reduce the charge current setting as they get closer to 100%.

Guessing the GX cuts the big charger first.

It would be interesting to see a graph showing the charge current and the charge current limit. You can do this with a custom widget in the advanced section of VRM. You'll find the metrics under BB artery monitor.

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kudos50 kevgermany ♦♦ commented · Apr 22 at 09:16 AM

Multi's are still doing 1500W when MPPT RS has reached 0. The thing I do not understand is that DV-PV feed-in to grid should always keep maximum power point. Why is not simply inverting etc.. The system has more than enough capacity to invert all DC-PV.

<edit> please don't mind the increased output after the interruption. Way too many clouds at that time to state that ramping down started 10mins earlier.