Kiev, I must apologize for the incorrect information. It seems I was measuring yellow wire at C-106 connector instead of C-111.
This idea that I was measuring the wrong wire came to me only today.
Now about the battery. As I did not have a new battery, I decided to try my charger"s function "recondition + 14,7V". After fully charged, the battery was charged up to 13,25V. After putting it in the car, it showed 13,12V. The car started, I was able to drive for 12 km and after that, I was able to charge the car
But today, when I found that I was measuring the wrong contact, I decided to measure it again. The battery voltage was only 12,69 V (last night we had -18C). I was not able to start the car. I got error P1A15 again, yellow warning sign, and red battery sign. I tried to measure the voltage at contact 107 and it was 0V in the positions ON and START.
I deleted the error and tried to start the car after 10 minutes. The battery voltage was now 13,48V before the starting. The car started and battery voltage became 14,63V with turned-on headlamps.
I tried to drive a car in the shed back and forth. Then turned off and again on. I got a yellow triangle warning light but the car was able to drive back and forth. I turned it off and again turned it on. The warning light disappeared without deleting the error.
After few days I will try to start it again. And see the situation.
Then I plan to buy new battery and see if that helps.