Balmar SG200 soc suddenly drops to 4%

[Wainui]

My SG200 smart shunt was reading 63% when it suddenly dropped to 4%
After I turned on the charger it slowly climbed back up but now the battery is in float voltage but the sg is at 48%.
I will continue charging overnight.

[Wainui]

So it happened again!
I’m at anchor after 2 days the sg was reading soc 63% and soh was 100%. The battery voltage was at 12.4.
I fired up the motor to charge and the soc dropped to 8%.
The alternator was putting in 43amps.
The soc is slowly coming back up.
Any ideas on what is happening with the Balmar SG 200?