The problem I had occurred this morning. I was driving to Stockholm 110 km from home. When I got there it was heavy traffic I spent a lot of time standing still in idle. Then some lights went on in the dash. Airbag, ABS and TractionControl went on but with a fade. I went out in the next lane were the traffic flowed ( I was on an exit ramp) and the lights went out. But when they did the battery light went on for a short while. Then I ended up in another traffic jam and after a while of standing still on idle the three lights came back on again. I was able to turn around and when I got up to speed the lights went out. Temp guage showed 100°C.
I decided to park the car, opened the hood to let it cool down. After 30 minutes I tried to start it and it was almost dead and wouldn't crank. I left it and went to my visit I was going to.
Then in the afternoon I got back, it started without any problem, cranked as always. I drove all the way home without any glitches.
I took a voltage reading on the battery and it showed 12.3V. Kind of low I think.
I guess this was temperature related, outside temp were 23°C. It should handle that, it's not extreme. Both fans are running, coolant is OK. It might need a flushing.
Hope it gets better when I change the alternator.
Jan