Hello everyone, I have two customers for whom I installed self-consumption systems using a MultiPlus-II GX 5 kVA and a Pylontech Fidus 5.12 kWh battery, following the recommendations of a supplier that delivers preconfigured Victron systems — supposedly plug-and-play. Unfortunately, after a few days of operation, both batteries went into fault mode (one at each of my two customers) at 95% charge. My supplier tells me that it is a battery problem and that I need to contact Pylontech. I find this hard to believe because the same issue has occurred simultaneously on two separate installations. I am therefore wondering whether it could be a configuration problem: charging/discharging voltages set too high? Firmware update issue? Undersized DC cabling? Unfortunately, my supplier is not very responsive, and I don’t know how to contact Victron for help.
It seems that your battery is undersized for the inverter, and has probably protected itself.
full battery data at : https://global-site.oss-eu-central-1.aliyuncs.com/upload/2026/06/23/EN-SD-250424-Fidus-Residential%20Spec-Pylontech_1782186321819.pdf
100A is a bit too small for the inverter, and the voltage is on the low side too. Make sure that you have BMS comms to the battery working also.