I was surprised to find that the battery in the 2017 Doblo was not a specific Stop/Start type. It could have been swapped during its build as a wheelchair vehicle, if there were other non S/S vehicles around, but the battery does appear to be the right age, so perhaps is correct.
When I bought it, beginning of the year, it was 6 years old with just over 12k miles, so likely to have spent a lot of time not fully charged. When tested, the battery showed good, but not fully charged. After a few months of regular use, suddenly the S/S started working, but only for a few seconds at a time. Longest 'off' has been nearly a whole minute, but mostly it does 15-20 seconds. It did throw a wobbly once, engine stayed on once stopped, then cut out as I put the clutch down to move away. Leaving out of gear, releasing the clutch caused a restart, thankfully. Then later same day, it didn't restart after stopping, requiring the key to be turned. Missed the temp traffic signals, oops! Been behaving ever since, although rarely operates.
Now we're out of the bowling season, the Fabia usually only gets used on Wed and Thu, and rarely between. Battery is original, so nearly 9 years old. Usually, if the battery sensor determines not good enough, it will not operate the S/S for the whole journey. But a restart will wake it up again. It tends to work well on Thursdays.
S/S is usually good for learners, as it will recover a stall. Except sometimes with the Fiestas, if the stall was particularly violent, it would refuse to restart, demanding a manual off then on again. With the push button start, that was a slow painful delay, just what is needed with a nervous learner and a busy roundabout. I'd have like to put the Ford engineer who determined this behaviour, in the back of the car, with a learner, and stall it in the magic roundabout in Swindon. That might get his attention.