Phew, who would have thought an alternator would be so complicated.
I think that it is overcharging, because ign lamp comes on at high revs (5000) {it used to be 6500 rpm and was almost a makeshift change up light, but as you can see light is now on at lower rpm and I suspect it will just get lower} I must confess I havn't measured output at battery terminals, I just assumed that diodes were overheated and knackered.
On the topic of the pulley - outer diameter is 60mm and was from the valeo unit, I will swap this onto the recon unit. Any more input would be much appreciated before I put an order in with the folk at Caterham. Thanks for your help.
Strongy
Strongy - go on, wake the neighbours. 😬