question

@Kaplan78, there are a couple immediate things to check, although they would require something being connected in a manner other than as shown on your schematic:

1: Check to make sure that the shunt is connected in the proper orientation; that is, that the battery is indeed connected to the "battery" side of the shunt rather than the shunt being reversed;

2: Check to make sure that all of your loads are indeed connected to the "load" side of the shunt and that none are bypassing it... your schematic looks perfect, but make sure it's really connected that way;

3: Check to make sure that your total battery capacity is properly set in the BMV-712; that is, if you have the one 100Ah Battle Born battery, make sure the capacity is set to 100Ah in the BMV, and also that charge efficiency has been changed to 99% and that you've set the Peukert exponent to 1.05%

4: It's worth noting that the BMV calculates SOC by current measured, not by battery voltage, so the fact that you're showing 100% SOC while your voltage has dropped down to 11v just tells me that current is being drawn from somewhere that is not being measured by the shunt (ie, a load is bypassing the shunt) OR that the shunt is connected in reverse (which would make the BMV think that a load is actually a charge)

5: As an entirely separate and (mostly) unrelated matter, that 100mA fuse at the shunt power supply needs to be replaced with a 1A fuse at your earliest convenience. It is a relatively recently discovered known issue that the 100mA fuse originally shipped with these can result in a number of problems later down the line. It's not responsible for this problem, but it'll cause you problems in the future.