The first time the battery light came on my local garage took out the 'plug' with three wires that goes into the body of the alternator and cleaned the contact; that seemed to fix it and I had at least three months without the battery light coming on again but they did warn me that the three wires going into the alternator had dry and cracked insulation, with one wire partially cut but not all the way through. In the opinion of  fellow members of this forum could the condition of the three wires cause the battery light to come on?

yes i wold say so

1 hour ago, dezwez said:

yes i wold say so

Thanks dezwez, I'm hoping it is.

On 1/5/2022 at 4:24 PM, oberks said:

Thanks dezwez, I'm hoping it is.

The auto electrician found a short circuit on one of the three wires in question (which have been replaced) but unfortunately it didn't solve the problem entirely because, according to the auto electrician because a 'known fault' is that alternator brushes get stuck out of contact with the alternator slip-rings. So I have to have a new alternator fitted - see my new question! - Let's hope this solves the problem!

I had similar on the Focus.  It was cured by cleaning the main battery earth and alt/starter earth connections.