Smart charging issue??

[TheBaldManc]

Ford Fiesta 1.4 Petrol Titanium.

Driving along vehicle begins to flash various warnings on dash before going blank and ultimately cuts out. 

Jump-start the vehilce it runs, removed the jump leads cuts out again, check battery voltage when running and only get 10V, replace the battery, now getting 12V when running, replace the altenator, still only get 12V and slowly dropping till the battery is drained.

Vehicle equipped with a single pin connector to the altenator, disconnect the plug and check voltage vehilce now runs at 14v and holds charge.

I'm aware these are fitted with smart charging systems, however when the plug is connected I have no battery warning symbols on dashboard to indicate a broken wire from that wiring loom however the altenator won't pump out anything to keep the battery voltage up and going. Disconnect the plug as as mentioned the altenator pumps out like a regular altenator would allowing the vehicle to maintain power just leaves the battery symbol on dashboard because there's now a break in the circuit.

Any clues? 

Battery replaced / altenator replaced, wiring appears intact as no warning symbol on dashboard such as  the battery symbol when running and recongises when its disconnected. 

I'm leaning towards a faulty altenator but before stripping this one off and placing another new one on, thought I'd ask you lot am I missing something obvious 😂

[unofix]

When you installed the new battery did you reset the BMS ?

The system need to know that you have changed the battery for a brand new one.

https://www.google.co.uk/search?q=ford+battery+management+system+reset&sxsrf=ALeKk01gCs8DMNipQwB5RbrZECq8Co2MBg%3A1621381931549&source=hp&ei=K1OkYIzFHpCZkgWK2KSABg&iflsig=AINFCbYAAAAAYKRhO10dVqE37dqhYCok5uDM1p65efk6&oq=ford+batter&gs_lcp=Cgdnd3Mtd2l6EAEYBjICCAAyAggAMgIIADICCAAyAggAMgIIADICCAAyAggAMgIIADICCAA6DQguEMcBEKMCECcQkwI6BAgjECc6BQgAEJECOggIABCxAxCDAToLCC4QsQMQxwEQowI6BQgAELEDOg4ILhCxAxCDARDHARCjAjoFCC4QsQM6CwguELEDEMcBEK8BOggILhCxAxCDAToOCC4QsQMQxwEQrwEQkwI6BQgAEMkDOgcIIxDqAhAnOgcILhDqAhAnOggILhDHARCvAToLCC4QxwEQrwEQkwJQzApYld8BYNuZAmgPcAB4AIABjQGIAf0VkgEENy4xOZgBAKABAaoBB2d3cy13aXqwAQo&sclient=gws-wiz#kpvalbx=_UFOkYLXVE8WJ1fAP__ys0AM25