2004 alternator
 

Batterie doesn' get charged on idle or low rpm
belt tensioner is on the second mark, but i can press the belt down to the tensioner
Batterie voltage does not go over 12.7V even on higher rpm
Bad belt, tensioner or alternator?
How much torque should the tensioner have?
Can i replace the alternator without removing halfshaft and exhaust?

Thanks in advance for any help

Sounds like you have a bad alternator and yes you do have to remove the half shaft but not the exhaust...

That means draining the trans and taking the whole shaft out?
I read somewhere you can take motor mounts off and raise the engine to get the alternator out without removing the half shaft

I never heard about the mount thing but you don't have train the trany some may come out but not much....

just replaced the belt -alternator is charging -get 14.7V at the batterie, but it is whining pretty loud and got hot in a few minutes
I could turn the pulley by hand when the belt was off, but it had a bit resistance

let the alternator cool down started the car again -whining is gone, but now it is not charging under 2000 rpm

Replace the alternator. Remove the half shaft, The bracket the alternator is bolted to. You can also drop the cradle on the pass side aprox 1 inch if you loosen the cradle bolts on that side. every little bit of clearance helps on that job. hope this helps Kevin