BATTERY LIGHT FLICKERS !!!!

Hi Ive a golf Mk1 cabrio the battery light flickers on and the car is very stuttery!! is this the alternator problem, i have just fitted new battery but the light is still on please advise Thanks Jason
P.S tested battery while car is running and it was showing 12.4 v then tested with engine and lights on and it was showing 11.9 v how do i test the alternator ???

Yep, sounds like the alternator is faulty. Its probably just the brushes/regulator pack though, which can be changed with the alternator still fitted, in about 5 minutes.

you did test the alt, 11.9 is way too low paul c is right just fit new reg all wil be good again

take the brush pack off the back of the alternator, held on with 2 screws. make sure brushes are ok and reasonable length. next clean up the metal ring round one of the bolt holes, plus the mounting face for it on the alternator. last of all, look in brush pack hole and you'll see a metal prong, look at brush pack and you'll see a metal contact face this touches. clean prong and brush pack face and refit. if still no improvement new alt time