IWC Portugieser Automatic, power reserve display

Recently, 10 months after the purchase of my Portugieser Automatic, I noticed
that the power reserve display shows hardly any power increase after 24 hours
(wearing during the day, resting during the night). When I just bought the
watch the power reserve display was showing a fast increase after each day of
wearing. It seems that during wearing, the power builds up much slower than 10
months ago.

The first image shows the power reserve after wearing my watch during the day,
the second image shows the power reserve the next morning (after 15.5 hours of
rest), the third image shows the power reserve in the evening. The images show
that after approx. 24 hours the power reserve has even decreased a bit.

I wonder if this is normal after 10 months.

I think its depending how you move your wrist during work. When I am in the
office then I work mostly on my computer and so the watch will be not wound
much! Try to wind it up manually and I am sure it will be like on the day you
purchased it.

Thanks for your answer. The thing is that my work hasn't changed since the
purchase of my IWC. Therefore I would expect it should wind with (almost) the
same speed as 10 months ago. I'm just not used to an automatic watch that
loses energy during wearing (that's what it does currently).

I'd say it's time to have it checked at an IWC service center. There might be
a problem with the automatic winding system. When the behaviour was different
before, it seems something is not as it should.

I agree with Tilo, I would have your watch checked.

I personally do have two watches with the same caliber (Portugieser Autmatic
and Big Pilot). I also work in an office with not too much wrist movement.
Both watches gain about 1 day of power reserve during a standard office day.