Sorry if this has been already discussed.

I felt that the stock USB cable was thick and unwieldly, and that it put an undue strain on the connector on the phone side. Seeing as some friends of mine have had to replace USB connectors on rival phones at a great cost, I went to Clas Ohlson (a Nordic discount chain) and got a replacement cable which is much thinner and has a smaller plug at the Micro B end. (Exibel USB A to Micro B 1 m if somebody cares.)

The cable seems to work fine in both charging and data transfer, and I am now much more comfortable moving the phone around while it's connected.

I noticed also that the USB-cable doesn't fit quite optimal on the phone. One night before I tried to charge Jolla with N9 charger but it didn't work. The battery was 0% in the morning.

Last night I used Jolla own charger and I got charge symbol on the phone but the battery level in the morning is 50%. Could it be something wrong with the cable or battery level display?

The N9 charger usually works fine. Sometimes I use the Jolla charger, the N9 charger, or the Nexus 7 charger (2 A output max, but the phone just takes what it needs), depending on which one is closest.

Followed your example, the new cable is much more nimble.

I tried to use my old N900 cable - and lo, it works! The charger works as well.