Hello!
Normally, when DC injection from MPPT’s is active, the system does not respect the charging current limit set in DVCC (Dynamic Voltage and Current Control). This can lead to overcharging and potential stress on the battery.
To solve this issue, a custom Node-RED flow has been implemented, which continuously monitors the following parameters:
- Charging current limit from DVCC (
dvcc_current) - Actual battery charging current (
battery_current) - Battery voltage (
battery_voltage) - MPPT power output (
mppt_power) - DC feed status (
dc_feed) - AC grid input (
ac_in)
If DC injection is active and the battery charging current exceeds the allowed threshold (either the DVCC value or a fixed 50A limit when DVCC is disabled), the flow automatically calculates and applies a negative grid set-point value. This action reduces the charging power, effectively enforcing the desired current limit.
This solution ensures proper charging control even when the standard system behavior fails to enforce DVCC limits during active DC injection.
I attached the flow from NodeRed with this limitation.
Charge Current limit by Atelierul de Tehnologii.zip (2.2 KB)