vk electrical problem

[old55]

my son has av k 3.3 black has had a problem with the battery going flat in a matter of 15 to 20 minites then it got to the poinb that the battery went flat in a matter of minites for example after starting the car 3 or 4 times in a few minites the car died and when you turn the key on to start it again there is nothing no dash light no interior light i told him to change the alternator which he has done but am i on the right track but it still is doing the same turn the key on batteries dies

[vkberlina]

When the car is running is the alternator charging?

How many wires go to the alternator?

[ENV5]

dud battery maybe

[old55]

alterntor is charging
1 spade teminal and 1 bolted wire
tried 2 different batteries did the same to each