Think I have a battery issue so thought I would post up the issues I believe I have and get some feedback

Quick mention, I use to use elm327 and forscan, quite often this would say battery too low and had to start engine to program 

Now use OBDLink MX Bluetooth adapter and OBDLink app on my phone

It use to display a solid 14.5v when running but today it reported some fluctuations on voltage, at one point it stayed at around 12.9v until I pulled over and restarted the engine which was odd, then when running it kept fluctuating dropping down to between 13.7 and 14.1, then when in first and accelerating a bit hard the voltage was dropping down to 12.7ish. Towards the end of the drive home it stayed quite steady at 14.1v

Also noticed during this trip stop start was not working

Car is a 2014 fiesta titanium, at the moment I'm thinking the battery has given up the ghost and really need to get in a garage and get a load test done but in the mean time penny for your thoughts...

is it petrol or diesel? if diesel is it the Econetic version. I ask because the Econetic has some unusual charging feature where it only charges when your foot is off the throttle pedal to make it more economical and that would cause some strange voltage reading (eg. voltage drops when accelerating). I am not sure exactly how it works.

It's a petrol, 1l ecoboost

Some weird behaviour today too, stop start working again but fluctuating between 14v and 14.5v and again 2 out of 3 times when accelerating in 1st dropping to 12 odd volts

normal for a battery below 90% charge. it pauses charging when accelerating hard so more power goes to the wheels. when above 90% charge it will only charge the battery when decelerating in gear to save petrol. mine reads 12.1 volts when fully charged when driving but quickly returns to approx 12.6v when switched off 

If you get a new battery make sure it is designed for stop / start.

Had some more strange behaviour today, stop start not working again, high voltage readings today, had 14.7 to 14.9 this morning

Decided to pop it into a garage and get a battery test done, came back that the battery was fine but charging wasn't

Results were:

Battery Test - Good Battery - 12.43V, measured 638A SAE
Starter Test - Normal - 11.24V
Charging Test - High - 15.10V

Doesn't look good, I'm thinking maybe I have a bad alternator?

to me, it looks like it has been tested using a generic tester. these can give false errors when tested. the smart charge system does push 15+ volts when in a refresh phase so I would say the result above is normal. if you had the battery tested within 30 minutes of stopping the car the battery voltage could be lower than indicated. I would hook the battery up to a charger and ensure it is fully charged. then if it starts and stops as it should id leave it. if your still concerned then get it tested with the proper equipment.

Decided to check over the battery terminals as they looked dry/untouched and showed a small amount of corrosion

Cleaned them all up with a wire brush and needle files and also found that the main chassis grounding cable wasn't even metal to metal the part of the body is painted so only connects through the bolt, cleaned this off too so I have metal to metal and put grease over everything to protect from corrosion

So far so good, solid 14.7v nearly all the time, no random drops or anything at the moment, hasn't dropped down to 12 odd in first again and start stop is working

Touch wood all is good at the moment and fingers crossed will have no other issues