So last month, my car completely packed up, dials stopped ran rough, everything electrical went. Long story short the problem turned out to be the wiring loom between the alternator and the battery which fried the alternator, battery and fuse box.

 

However, since doing that, the battery light comes on after start, blip the throttle and it flags the alternator warning on the dash (L&K spec) an goes out.

 

Any suggestions? Have I missed a step?

This may indicate that the alternator sprague clutch is sticking part-open. Next time it happens, open the bonnet and look at the alternator fan or the drive shaft at the back to see if they're spinning at engine speed.

 

Or maybe that the battery is weak; 'tis the season for weak batteries to show up.

On 1/31/2017 at 12:02, KenONeill said:

This may indicate that the alternator sprague clutch is sticking part-open. Next time it happens, open the bonnet and look at the alternator fan or the drive shaft at the back to see if they're spinning at engine speed.

 

Or maybe that the battery is weak; 'tis the season for weak batteries to show up.

I did think this again as I've had a similar problem on my previous Octavia, but it's a "new" alternator. I'm also swinging towards the way of the tensioner too.

10 hours ago, Quiche said:

I did think this again as I've had a similar problem on my previous Octavia, but it's a "new" alternator. I'm also swinging towards the way of the tensioner too.

Er, the clutch is part of the pulley, and not of the alternator or the aux belt tensioner. You don't automatically get a new pulley with a new alternator.