Multiplus II & SmartSolar MPPT: Same charging settings but different charging behaviour

[billakisdrama]

Hello everyone. I have been dealing the the situation below:

System Components:

• Inverter/Charger: MultiPlus-II 24/3000/70

• Solar Charge Controller: SmartSolar MPPT VE.Can 150/85

• Battery Bank: Lead-acid (configured per manufacturer specs)

Shared Charge Settings:

• Absorption Voltage: 31.2V

• Float Voltage: 27.2V

• Equalization Voltage: 32.4V

The Issue: I have noticed a significant discrepancy in how these two devices transition between charging stages. Despite having identical settings:

1. The MultiPlus-II triggers Absorption mode below the 31.2V target.

2. The SmartSolar MPPT triggers Absorption at 31.7V (0.5V higher than the setpoint).

Resulting Conflict: When the generator is running during sunny periods, if the MPPT is already in the Absorption stage, the MultiPlus-II stops charging entirely because it “sees” a battery voltage higher than its own programmed Absorption limit. Effectively, the MPPT “pushes” the voltage higher than the MultiPlus-II is comfortable with, causing the inverter/charger to remain idle.

Questions:

• Why is the MPPT exceeding the programmed 31.2V setpoint to reach 31.7V before entering Absorption? At the Absorption state the voltage stays at 31,7V.

• Is this a calibration issue, or is it related to voltage drop compensation?

• How can I synchronize these two devices so they work together harmoniously when the generator is active?

[billakisdrama]

And here is the multiplus-II charging behaviour: