Hi everyone. I’ve just had my battery tested as my stop start has not been working and these were the results. As you can see if failed on one, does anyone know what it has failed on? Is it the battery or the alternator that’s at fault? Thanks.

It’s a 2016 Ford Kuga titanium.

Welcome!
I've looked at the picture and it seems to be voltage readings at 3 conditions and If I had to comment I'd say the alternator was a bit weak at higher revs but still should be charging HOWEVER I don't understand the diode symbol in the bottom section is it ripple voltage?
I'd say RT_M for the tester and come back when it is explained?
Plus, if it's the original battery, you've had your money's worth!
I always want to know more about batteries and I won't suggest testing the capacity which is another failure mode (and the most likely):
https://www.batteryuniversity.com/article/bu-806-tracking-battery-capacity-and-resistance-as-part-of-aging/

That isn't a battery test. It's only an alternator test.

Also not a particularly effective one for a modern car with smart charging. It's just giving minimum and maximum alternator output, with the calculated average between them.

The failure is where the alternator drops very low at some point while the engine was revved high. But that alone doesn't really tell us anything.

If you've got a multimeter, test the resting battery voltage. Ideally first thing in the morning. Leave the bonnet open for about half an hour so all the systems shut down first. Then see what the voltage reading is at that point.

Thanks to both of you for your reply’s. Its not the original battery, that was changed back 2023, and I had the alternator pulley wheels and belt changed last year, but not the alternator it self that is still the original one. I’ll have to get a garage to look further into this problem for me.

This is on this forum in a number of topics, but posted to save you searching for it.

Remember, this is only open circuit voltage, and does not give any indication of actual capacity. You need to switch on a significant load, like some halogen headlights, and see how quickly it drops!

I use this set up to calculate the internal resistance of a car battery.

Measure the OC Volts, then :

measur load Volts and current with a load.

Voltage drop :12.2-11.2 =1V

Current 4.23A

R=V/R ie 1/4.23 = 236, milliohm so about 5x too big ! A new battery of that type is typically 45 milliohm. not a good example, but below some figures from new batteries

Ca 2 Fusion	Fusion	500/52Ah	12.47	4.31	12.29	0.18	41.76
Ca 3 Fiesta	Fiesta	500/52Ah	12.40	4.30	12.20	0.20	46.51

Even 3 years may mean it needs changing (always living on borrowed time and warranty only covers manufacturing faults - increasingly rare)
Only a test with a benchmark agreed tester may help you decide (Midtronics used to be the only make Ford would accept) Halfords use a similar device. Best to charge it before that test. High discharge testers are another way to test one parameter.
As said there are multiple independent failure modes (like people) and capacity is difficult to measure without a discharge test:
https://sargent.zohodesk.eu/portal/en/kb/articles/leisure-battery-testing
For leisure batteries but the method is sound.

Cars booked in at my mates garage tomorrow, so will hopefully find out exactly what the problem is. Will keep you all posted. 👍🏼👍🏼

There is a huge list of conditions that all need to be ok for stat/stop to work.

Somewhere on live data on my diagnostics device I found a long list and it has pass/fail for start/stop next to each. If you find this info on diagnostics it will tell you what parameter is stopping the start/stop working.

From memory I think it's either under the body control mobile or engine Live data.

I'm sure forscan will show it somewhere, I use an xtool A30m (it's on amazon).

Frankly I've found the stop/start on both of the Fords I've had (2020 Focus, and currently 2019 Kuga) to be erratic - I've stopped worrying about it. Do the static test as someone else has suggested, with a multimeter. And also do the same test with the engine running - the latter should show 14 or 15 volts this shows the alternator is working well enough!