Hi again
I don't know what all this can do ..
I have changed the charger and when I measured directly from the charger I got the value to 14.5 volts. While measuring the battery terminals I got 13.5-13.9 volts.
I don't know where this 0.5-1 volt lost. Temporarily solved the problem by placing another wire alongside the original.
Now when I measure the voltage at the battery terminals I get the same 14.5 volts from both measuring points.

I flickered the lights at idle and did not charge the battery properly while driving. I'm looking forward to seeing how the power steering works now.
Previously, I noticed that in the hot summer it didn't work properly. I was just wondering if the cause was a bad battery voltage.

Thanks and sorry I used the google translator directly for this post;)

There is a common problem where the alternator load signal wires break near the gearbox. Does the battery light illuminate with just the ignition switched on (engine not running and without your temporary wire?)

Sounds to me like the cause was bad power cable. Was it the positive or earth that you paralleled?

Could be just down to cable losses, as an old gent  called OHM said" when a current flows in a circuit................". Alternator + goes through a cable to get to battery. -ve goes through ( usually engine ,then earth strap). Only real way of finding this is to use a high impedance meter to look for ?0.5V  . From my older days 0.5 was top limit on starter solenoid contacts.

I'd be more worried if battery voltage when starter engaged was less than 12v.