16mm² on the wiring diagram, but no harm in going thicker. M8 crimp at alternator end, M6 at fuse end. See what a local car parts shop has or can make up for you. Measure length and don't make much longer.

I'll get it, hopefully tomorrow!

just gotta be sure now, is it the bottom cable that comes from the alternator output (picture 1)

 

or is it the one that goes to the fuse to the left? (Pic 2)

1 hour ago, Wino said:

16mm² on the wiring diagram, but no harm in going thicker. M8 crimp at alternator end, M6 at fuse end. See what a local car parts shop has or can make up for you. Measure length and don't make much longer.

 

Guessing it´s the one that goes to the fuse on picture 2. Next question, are you sure there are no other connectors from there to the alternator? This cable more looks like a 8mm2 rather then 16mm2.

It's the one in the second picture.

Look at how the copper strand ends in the crimp terminal look corroded, in comparison to its neighbouring cables. As does the captive nut. 

Yes 16mm squared conductor cross-sectional area is specified in the wiring diagram. Automotive cables often have a deceptively thin outside diameter in relation to the conductor CSA. Thin insulation.

7 minutes ago, Wino said:

It's the one in the second picture.

Look at how the copper strand ends in the crimp terminal look corroded, in comparison to its neighbouring cables. As does the captive nut. 

Yes 16mm squared conductor cross-sectional area is specified in the wiring diagram. Automotive cables often have a deceptively thin outside diameter in relation to the conductor CSA. Thin insulation.

Yeah i noticed, that´s why i took it apart and cleaned the connecting areas. It´s been hot there like it´s bad connection

im thinking about getting like 1.5m and then mounting it alongside the big cable loom.

There's plenty of melted plastic around too, now that I look again at your photo.  

On 08/08/2021 at 15:45, Wino said:

There's plenty of melted plastic around too, now that I look again at your photo.  

update

just installed the new cable. Now i have 14,2V on the battery on idle (battery not fully charged yet).

it seems to work fine now, going to try it out nearby the following days.

extremely greatful for your help!!

Glad I could be useful.

 

Looking  back at one of your pictures just up there a bit ^; the battery posts and battery clamps look like they would benefit from a clean-up, if you haven't already done that. Any contact resistance there is most unwelcome.