Zazzalii
New Member
Hi everyone,
I’m using an Axpert Max 8kW inverter with a 48V 100Ah LiFePO4 battery (LIO II-4810E) and 8 x 550W solar panels.
Originally, I had the system configured in LI-B mode, which worked fine for charge/discharge logic, until one night the battery dropped too low and triggered a UVP (under-voltage protection) shutdown from the BMS. Since LI-B doesn’t allow adjusting the cut-off voltage (fixed around 44.8V), it put the battery at serious risk.
To prevent that from happening again, I switched to User-defined mode (UC) and manually configured safer thresholds:
This mode gave me full control over discharge protection, and it worked well except for one major issue:
The problem:
In User mode, once the battery reaches 100% (around midday), the inverter stops charging entirely even if solar production is still available and the battery begins to discharge again (drops to ~70–80%). It prioritizes supplying loads and does not resume charging, which defeats the purpose of maximizing solar usage.
This behavior does not happen in LI-B, where charging logic works as expected and the inverter recharges again after consumption. But again, LI-B exposes the battery to UVP risk due to the locked low-voltage threshold.
Additionally, in User mode, the SOC readings become inaccurate on the inverter display, even though voltages are fine. The BMS reads the correct SOC, but the inverter seems blind to it.
My current situation:
I went back to LI-B to restore proper charging logic… and once again, I experienced UVP shutdown overnight, confirming my earlier concerns.
My question is…
U1: 72.07
U2: 12.28
I’m not using parallel inverters.
Thanks in advance to anyone who can shed light on this!
I’m using an Axpert Max 8kW inverter with a 48V 100Ah LiFePO4 battery (LIO II-4810E) and 8 x 550W solar panels.
Originally, I had the system configured in LI-B mode, which worked fine for charge/discharge logic, until one night the battery dropped too low and triggered a UVP (under-voltage protection) shutdown from the BMS. Since LI-B doesn’t allow adjusting the cut-off voltage (fixed around 44.8V), it put the battery at serious risk.
To prevent that from happening again, I switched to User-defined mode (UC) and manually configured safer thresholds:
- Program 29 (Cut-off): 47.5V
- Program 12 (Back to utility): 48.0V
- Program 13 (Back to battery): 52.0V
- Program 01: SBU
- Program 16: OSO (solar only charge) or SNU (solar + utility on cloudy days)
This mode gave me full control over discharge protection, and it worked well except for one major issue:
The problem:
In User mode, once the battery reaches 100% (around midday), the inverter stops charging entirely even if solar production is still available and the battery begins to discharge again (drops to ~70–80%). It prioritizes supplying loads and does not resume charging, which defeats the purpose of maximizing solar usage.
This behavior does not happen in LI-B, where charging logic works as expected and the inverter recharges again after consumption. But again, LI-B exposes the battery to UVP risk due to the locked low-voltage threshold.
Additionally, in User mode, the SOC readings become inaccurate on the inverter display, even though voltages are fine. The BMS reads the correct SOC, but the inverter seems blind to it.
My current situation:
I went back to LI-B to restore proper charging logic… and once again, I experienced UVP shutdown overnight, confirming my earlier concerns.
My question is…
- Is there a known way to make the inverter resume charging in User mode after it hits 100% and starts discharging again?
- Any workaround, firmware fix or advanced config that would allow both proper charging logic and safe low-voltage protection?
U1: 72.07
U2: 12.28
I’m not using parallel inverters.
Thanks in advance to anyone who can shed light on this!
