Hi Luke, I had a C2 a few weeks ago which had just been fitted with a Recon alternator from A.P. That would charge if the vehicle was revved highly and would keep charging once revved until it was turned off again.

As steve has just said, That one also turned out to be the wrong type alternator.

The older type alternators require a Warning light wire in the other terminal to enegise the alternator to make it charge at low speed, I would think these later alternators would charge ok simply with a Battery feed wire connected. ( I will test one to confirm )

These later alternators only have a wire in the DFM terminal which is an ecu monitoring signal.

You could pull the plug out and use a warning light or test lamp connected between Battery pos and the other terminal in the 2 pin plug of the alternator and see if the light comes on and goes out OK. ( Thats basically how most alternators are tested on a test bench )

Does the car start ok on its own battery power. ?? If not fit a substitute battery.

Have you checked the voltage directly at the alternator body and B+ terminal. ??

H.T.H. Tony.