LiFePO₄ (JK BMS) Battery Not Charging to 100% During ESS Scheduled Charge Despite Solar Surplus

DIY
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Hi everyone,

I’m experiencing some unexpected behavior with my Victron ESS setup, and I’d appreciate your input.

System configuration:

  • Cerbo GX
  • Multiplus II
  • 2 Victron MPPTs (DC-coupled)
  • LiFePO₄ battery with JK BMS
  • No external PV inverter (e.g., Fronius)
  • No external grid meter installed yet
  • ESS mode: Optimized with BatteryLife
  • A scheduled charge program set from 10:00 to 14:00 with a target SoC of 100%

Despite excellent solar production during the scheduled charge period (over 4kW), and with visible export to the grid, the battery remains stuck around 90% SoC and does not reach the 100% target. In fact, I noticed minor battery discharging during that same period, even though the system shows that it’s in the “Scheduled Charge” mode.

My concerns/questions:

  1. Is this behavior expected with BatteryLife active, even during scheduled charge periods?
  2. Could the absence of an external grid meter be causing the system to misread energy flow and prevent full charging?
  3. Is there any way to force the battery to fully charge to 100% using solar during the programmed time?
  4. Is this setup with a JK BMS fully compatible with ESS logic, or could there be communication or control limitations?

I’d love to hear if others have faced something similar, and how you’ve solved or worked around it (e.g., using “Keep batteries charged” mode during that time, or installing a Carlo Gavazzi meter).

Thanks in advance for any guidance!