Ford ka battery light stays on

I had a similar problem with a Volvo ages ago. With a new battery, I paid to have an alternator replaced over and over. Finally paid to have the alternator changed over to a generator. Turned out - the new battery was the problem. It was ... broken from day one. Just a thought.

Any gauges that do not read correctly like they should ? Sounds like a bad intake air temp sensor or coolant temp sensor

open or shorted alternator circuit (control wire)
let your auto store test the alternator charging
on and off the truck.
inspect 3 wire connector for burn or lose connection
disconnect 3 pin wire and start the engine.if the light stay on you have shot to ground.

The small clips break on these Ford Ka roller glove boxes and the are only available from ford .
The old one can be taken out with a pliers.
The new part will simply slot into the small rectangulay hole and just clicks into place to fit.
Sometimes the get dislodged and stay attached to the small locking point on the lid.

That suggests that the problem is in the harness, something in the connector or wiring is causing an open circuit. You will need to have the circuit tested to find the fault. Ford alternators have known connector issues & new aftermarket connectors are readily available at most auto parts stores.

The major cause of this is the overhead lights left on.

Could be the small bulbs in the speedo unit have simply blown over time . You just remove the speedo unit and they tun about 90 degrees to unscrew . They cost a few pounds and you can get different colours these days.

Ignition switch?

Get the alternator checked. It should be charging at least 13.8v.
A normal voltmeter will work across the battery terminals.

Altenator not charging.Start the truck up and pull the possitive cable off the battery and if it stay's running then the altenator is working right but if the engine quits the altenator is no good