Ok i have had the same set up for well over a year. The only thing that has changed is my sub. The set up is fine and suits my needs. However as of late my battery light has been coming on at random times, Mostly when i have my lights on and the system on. If i turn my lights off and turn the system down and keep the revs up the light go's off after a while. I have had the battery tested and its at 100% so does that mean i need a new alternator ?

yes, likely either the alternator or its associated voltage regulator.

Cheers Shiny, Is there an easy way to tell if its the alternator itself or the voltage regulator ?

id change the voltage regulator first..

its only a ~$20 part compared to a $150 alt rebuild/changeover...

Ok, so were would i be best to get that from ? Mechanics or an Auto electrician ?

EDIT: I found a shop on ebay that sells these for $40 including postage, Is that a decent price ?

not sure..

but try your local repco, super cheap, autopro's...

Pull out the regulator and see if the contacts have any meat left on them. If theres none on there, then chances are thats your problem.

new regulator was ~$30 from repco when i did one back in Jan.

VS often the alternator bearings go too - or the rectifiers. An auto elec would be able to test it for you and give a definite answer. We had to replace the one in our VS about every 4 years.