Update 2 — Root cause identified: VRM scheduler corrections cause throttling
Following a suggestion by @UpCycleElectric to isolate the VRM scheduler’s realignment effort, I blocked all outgoing internet traffic from the Cerbo GX at the firewall level at the start of a charge window.
Result: continuous charging at 7kW for the entire window, no throttling whatsoever.
As soon as internet was restored, the familiar pattern returned immediately.
I also found and monitored the internal “set target SOC for this time slot” value on the Cerbo. Without internet this value remains stable throughout the quarter. With internet connected, it drops by nearly 2% shortly after each quarter-hour transition — consistent with the VRM scheduler sending a corrected (lower) target after receiving the updated SOC reading.
This confirms that the throttling is caused by periodic schedule corrections sent by VRM, not by VenusOS itself, the battery, or DVCC. VenusOS executes the schedule correctly — it is the mid-window corrections from VRM that repeatedly adjust the target SOC downward, causing the inverter to reduce charge power each quarter.
This is consistent with what @dognose described in the related topic Dynamic ESS does not charge fast enough to reach target SOC: VRM sees the integer SOC lagging slightly behind the expected value just before a window transition, corrects the next window target downward, and by the time the SOC flips to the next integer the correction has already been applied — reducing effective charge power for the entire next window.