Hello guys,
As we found out like many otherrs, many recent US3000C and even US5000 are showing randomly "internal failure" alarms on the GX. Whether it is a single battery or a cluster of several in parallel, the message is often relayed at various times during the day, and is not dependant on the SOC nor the CH/DCH status. After many exchanges with Pylontech's engineers and debugging through Batteryview, we share the results and how to solve this issue.
Internal failure is actually relayed through the CANBUS by BMS when there's an imbalance between the 15x cells in one given US3000C/5000 pack (74 / 100Ah). As you can see from the debug files below, one cell in the slave battery actually overshooted to 4000mV, which obviously cause the battery to send an ALARM signal to the system (system fault 0x8), and the GX shows therefore "internal failure", WITHOUT being more specific. It is actually the MASTER battery which shows up an alarm and sends it to the GX.
At first we were worried about such abnormal voltages readouts on cells. After exchanges with Pylontech, we found out it is actually not possible that one cell reaches such high voltage (indeed it would compromise the safety and possibly brings on thermal runaway). Rather, it is a sampling error by the BMS which is apparently fixed by the latest firmware version (depending on the S/N of your battery), 1.7 or 2.8 (depending on the serial number). We have thus applied the patch and so far we haven't got the alarm again.
Hope this helps !
