1999 Renault Espace alternato/ battery not charging

I have a 2.2td espace t reg. I bought it a few months ago and I had the alternator removed and reconditioned as I was told it was not charging. When I got it back the battery remained on all the time and it would also stay 'stop'. The battery didn't run flat untill a couple of months later and then I started to check the voltage and found that the alternator was not charging un less I revved the engine fully and then it would start charging 14+ volts. Sometimes it would then stop charging or sometimes it would then stay charging.
this became annoying when driving around I was having to rev the engine full belt to get the alternator working and then finally it seemed that it stopped working altogether.
i could afford more garage fees as I thought that maybe it hadn't been done properly in the first place, so I stripped it down myself and went and got a fully reconditioned unit and put it on the vehicle. Very awkward in deed.
when I started it it had the same problem.
either I am the unluckyest person to get two faulty alternators or the alternator is not the problem.
can anyone help me with this. The only thing I thought of is that the main lead to the alternator also has another lead also but there are two connectors on the alternator. I thought I haput it on the correct one but tried it on the other one also anyway. Also there is a fitting on the alternator for a push on type connector but I could not see and wires that would go on this at all.
any help would be great
cheers