Greetings,
Just a quick update on my BSL battery saga.
The replacement 7kWh battery I received last October is performing flawlessly – virtually no cell drift, deep discharges are smooth, no issues at all. However, my other three batteries, manufactured in 2022 and installed in May 2023, are still giving me plenty of headaches.
Battery 2 (Slave 2): This one, due to a weak cell #8, consistently shuts off at around 18% SoC during discharge. I’ve set my ESS to switch to grid at 30% SoC, so this battery’s limitation is currently managed and not a critical problem for system operation.
Battery 4 (Slave 4): This is the real culprit. It still reports a full capacity of only 100Ah, instead of the “purchased” 135Ah. Following the agent’s advice, I performed two deep discharge cycles (down to its LVC shutdown). The first full recharge pushed its reported capacity to 110Ah, but the second cycle yielded no further change – its capacity reading remains stubbornly stuck at 110Ah. On top of that, 4 of its cells refuse to balance. I strongly suspect the BMS firmware or the BMS itself is corrupted. Another glaring symptom of a firmware issue is its incorrect cycle count: it shows only 84 cycles, compared to over 650 on the other older batteries, despite being physically the same age and always connected to the main busbar.
I’m convinced this Battery 4 is the primary reason for the uneven discharge across my entire bank. I’m currently in contact with the agent to arrange a repair or RMA of the unit. The saga continues…
Regards,
Joerg