The Lotus Grand Tourers

Battery light comes on from time to time and voltmeter shows normal values all the time.
This is happening since I replaced waterpump.
All alternator connections seem ok.
It flickers most a low electric load and less when lights are on ???

alternator- belt to thin ?? - se if its freyed at the edges,
belt not tightened enough ?
guessing you have checked batteru connections
or it might just be the alternator thats starting to give up....