Sounds like it could be a bad ground if you're seeing proper SoC and battery voltage.

 

For which "ground points" I can check proper connection? Where main these points are?

 

Outer and inner pad isn't always the same thickness. I mean the way the caliber pistons push the pads. So even it's OK thickness on the outside doesn't mean it's OK thickness on the inside pads.

 

I checked pads on both sides on every wheel in local workshop and used contacts cleaning spray for connectors on wires on inner pads.
All eight pads are with proper thickness.

 

12,5V is the minimun... try to check with a voltmeter the voltage directly on the battery if the value is the same.
If is higher on direct measure, may be you have a ground or fuse problem.
If si 12,5V could be that you have a faulty battery

 

I have 0.2V-0.3V higher battery voltage in direct measuring by voltmeter, than in MES diagnostic.
My battery is one month old.
What kind of fuse problem could be present and where are "ground points" for check?

 

low brake pads warning comes way before brake pads are completely worn. usually pads can last even 1000km after warning. of course depends where and how you drive.
warning also can be triggered if wire touches ground.

 

Today I measured 12.8V by voltmeter on the two dedicated points under the hood.
Additionally, I checked the ground quality by measurement of voltage difference between some point of chassis and negative pole of battery and measured approx. 0.005V (i.e. 5mV). It is a sign that ground is OK.
Because my rear pads are weared more than 50%, maybe the are for replacement.
Thanks all for comments and I will inform you about progress.

 

My IBS detected by MES (in the Body section of diagnostics) is 85%

 

My SoC was always below the 65% threshold unless I was on track for a couple of days, then it charged up. Since I had the IBS replaced, it's been perfect. The IBS was working, but I suspect that it was just reporting incorrect values so it never fully charged the battery.

 

I replaced rear brake pads in local workshop yesterday.
Old pads are thinned exactly to the level when sensor is visible and sensor's cable is broken by friction with disc.
New Brembo pads were thicker than 16mm (factory data) and have to sand to proper thickness, otherwise they could not fit.
Well, it wasn't false alarm...