Ka has a smart charge system

Now when the smart charge gets a fault the alternator reverts back to a normal alternator and charges at 14v and the light will illuminate

That means there is poss wiring or multiplug fault usually on the blue signal wire

Also Ka suffered from water ingress into the main wiring loom to the ecu

I changed about 15 looms when I worked for fords in 2003-2004

I'd say check wiring across front of car to alternator for breaks or corrosion