battery light comes on after driving for 2 mins

[total_vauxhall]

right so the first time i drove the car last week to the mot center on the way there the battery light came on so i thought maby a loose battery conection so i turned the car off checked every wire they all seemed fine fired car back up and light was gone then on the way home same thing. so after getting home i got a next to new alternator out of the shed and changed it over drove the car tonight with new alternator same thing light came on about 1 mile down the road turned the car off fired it back up light was off for about 2 mins then it came back on does the same thing every time . so i have changed the alternator and the battery is of my other nova and has always been fine / the wiring is nice and tight and the earth strap is brand new ? any help please .

[Graeme]

What voltage isthe alt giving out? Sounds like its over charging to me? Maybe a fooked rectifier

[total_vauxhall]

sorted it now . for anyone else that ever has this problem . it was my clocks i fit a set of sri clocks in the car and for some reason the light would come on about every 1 or 2 miles ( the sri clocks have 2 battery lights one is a big round one the other is a small squere one at the bottom ) and for some reason the clocks were stoping the alt from giving out a charge i hav fit the standard 1.2 clocks back in and all is fine now with battery charging as normal.

[Jon_nova1]

the wire that goes from the alternator to the clocks acts as a signal wire for the charging circuit

[total_vauxhall]

blue and white one yea ?

[Jon_nova1]

thats the one, i can't remember if its positive or negative that gives the signal though