Hi Hercules,
I've a doblo cargo maxi, 2.0, wouldn't start after a 4 minute stop, this after 3 and half hour motorway driving in italy. recovered to fiat dealer. asked if i'd had my lights on! i said yes it was dark . . . he said it's the battery, changed battery and all ok. Point being it was making smelly dpf regenerating smell for a 800+ motorway miles previous to that and was 7 months old, 45000 miles. All sorted under warranty but as you can imagine i was amazed when he asked if i'd been driving with my lights on!!! IMHO Definitely worth checking the battery. It's been good as gold since then.