Hello
my seicento battery light is on and only goes of when i rev the engine is there some small problem or is the alternator just broken ??

Do you have a multimeter? Measure the battery voltage when the engine is ticking over, and again at fast idle (>2000 RPM). Measure again with the engine off. You should have 13.4V when the engine is on and 12V when it is off.

If the alternator drive belt is tight then the alternator is dying.

First make sure all connections are tight.
Check the earth cable from battery to gearbox. These corrode inside the cover and cause poor connections, which could give your symptoms.

With the alternator off, it may be possible to replace the brush box/regulator assembly. As long as the slip rings inside are in good condition, a replacement regulator/brush box can cure the problem. Often the copper slip rings, that the carbon brushes rub against, will wear until their internal connection is exposed, then this tears the brush very quickly. If yours is like this, a replacement alternator is needed, unless a specialist near you can fit new slip rings.

thank you for your reply.
well i few days ago replaced regulator assembly as some ppl thought that was the problem .
but as i took the alternator off and but it back in i hope that the issue is some loose wiring.
can i fit the new slip rings myself or is that bit too much for an novice??

The slip rings are soldered onto the main shaft, with a thick wire inside. Possible to do yourself, but easy to make a mess. An exchange replacement is a lot easier, and should come with a warranty.

once the alternator light goes off does it stay off?