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LV6548 stopped charging SOK battery

akadbl

New Member
Joined
Jul 28, 2022
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5
I upgraded my off-grid solar system with a new MPP LV6548 and a new SOK server rack battery. I have 860W of solar and typically very light loads. (I'm planning to upgrade the solar panels and add another battery later as I see the LV6548's idle consumption is higher than I expected, sigh.) Anyway, I got them installed, battled the firmware update (see other thread), and the system was working fine with PYL communication enabled. The battery discharged and charged as expected. I replaced the fans with quieter and more efficient ones (see other thread) and the system continued to behave fine. But after several cloudy days and some unusual loads, I awoke to the SOK SOC stuck at 2%. I realized at that point that the LV6548 wasn't charging the battery: despite the sun, it showed a low number of PV watts (which I now understand is not the offered watts but rather the consumed watts). The LV6548 display said "Low Battery" below the "SOC bar chart". Connecting a PC to the BMS and running SOKTools showed the Battery-Chg-MOS-ON indicator on but the Charging indicator off. There was an Alarm Status "SOC Low" but no Protection Status or Fault Status. Voltage was at 48.55V. I theorized that something in the BMS/PYL communication protocol was telling the LV6548 to not charge so I reconfigured the LV6548 (05 setting) to USE (user settings) instead of PYL, set the charge voltages (26,27) and current limit (02). Then everything started working fine. The charging indicator was on, the provided watts ramped up to 600+, and the battery started charging normally. Last I looked, it was at 27% SOC, 53.445V, and charging at 11.73A.

My question is, why did the SOK BMS stop telling the LV6548 to charge? Is there some setting I can change to prevent this kind of "lock up"? I had hoped with this setup to use closed-loop communication but perhaps it's not necessary/possible? Thoughts?
 
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