From the MSN article linked below:
“ UK-based shipowner Zodiac Maritime has since confirmed that the fire originated in the section of the vessel carrying electric vehicles.”
I'm under the assumption that these are roll on/roll off carriers and that cars themselves are driven on and off (so they have some level of charge or fuel).
I know that batteries (apparently) can "just catch fire", I just don't know what the risk of fire to charge capacity of the battery is.
It’s a much higher risk during charging as that is when the structures typically form, but they can also be borderline and then ‘cross the border’ suddenly when just sitting there.