Hi there Declan good evening to you
and sorry for the delayed response
Ok nearly all stop/start concern I see lie with the battery state of charge (SOC)
This is nothing to do with the battery condition itself
The battety SOC is a calculation(algorithm ) that is carried out by the BCMii to determine the SOC
There is a sensor on the negative terminal of the battety called the battery monitoring Sensor
This takes temperature /charging voltage /time into considerstion the BCMii then used the data and calculates the SOC of the battery
If the SOC is below 72% the stop start will not function
This can be checked using the ford ids diagnostic computer
You will find yours will be in or around this region
We find that vehicles that do short cold journeys are more prone to a lower SOC
regards ***** ***** temperature issue impacting the stop /start this is doing what it should do (in a way I will describe further down the post )
Basically the BCMii sees a voltage drop and then says to itself it doesn't need the stop start as there are more important functions that are needed
An example is that if the vehicle has stopped at a junction and the engine cuts out and you press the heated screen button it will start up immediately as it sees a more important task than the stop start
This system is very complex and clever
There is also a self test for the stop start that lets you know it's working but sonething is inhibiting it most commonly the SOC is below 72%
Back to the temperature issue although it's the correct operation ford have released software updates for the BCMii and HVAC modules to widen the parameters and allow further temperature fluctuations (these updates can only be done using fords ids )
In nearly all cases with low SOC we deep cycle charge the battery in place overnight this brings the SOC up to around 96%
If you need anymore help or advice on this issue please let me know and I will do my upmost to assist you
If you are satisfied with my answer /advice
PLEASE REMEMBER TO RATE MY ANSWER
Kind regards ***** ***** and have a evening
Brian