My 2010 +4 has the tool tray and an aluminium plate on the rear bulkhead for access to the battery. I fitted a socket on this plate and a brass ferrule on the hole in the carpet so I could plug in a battery conditioner.

Just a further note on a previous subject from me.
My car came with 3 keys.
to date one immobiliser module has dropped out and been lost- another dropped out but saw it fall and retrieved it - third one was loose . I have now Araldited the two remaining in place.
it looks like they rely just on a 'push fit' as mine had no sign of any adhesive to hold the module in place.

I have been lucky they fell out at home other wise car would have needed recovery and cost of new modules and ECU programming. DO CHECK YOURS