Help! Battery Light
 

I just replaced the alternator and battery on my 1990 Honda Civic Si HB with a D16A8 Engine swap. After the new alternator was installed my battery light comes on when the engine is reving over 3000rpm. Other than that it is running ok. I was just wondering why the battery light is coming on?
If i put a capacitor on would it help?



Oh Yeah and I have a sub and amp plus some alpine type S speakers.

have your alternator tested you may have gotten a bad one, also check your connections.

is the belt slipping?