It really needed diagnostics and proper examination before starting to replace things. At this point, you don't know if the recon alternator is a good one, you don't know if the battery is a good one, if it's original it's long overdue for replacement (we recently had to replace the original battery on a '06 Vectra-C).

Get it to a good auto electrician for a proper check and then move forward from there.

Edited by RT on 18/02/2016 at 03:18

Still sounds like alternator trouble to me. Connect a voltmeter across the battery with the engine running, you should have about 14.4 volts, much less and the alternator is u/s

If the voltage drops it will cause things to stop working as much equipment require the full on charge battery voltage. Does the ignition light go out when you start?

I suppose the belt is not slipping?

Agree with above but I am not sure if the Vec C has smart charging so the voltage could be higher or lower than that.

I would make sure you have a good earth to the battery - I have seen low volts at the battery only to rise when a bad earth was found. Get a jump lead and clamp one end to the battery negative terminal and and the other to a good ground point on the engine - lifting eye, or directly onto the alternator body if you can get in close enough

Check the voltage with the engine running with and without the jump lead - just disconnect at the battery without turning off the engine