On Wed, 31 Aug 2016 22:57:49 -0700 (PDT), harry wrote:

If you are leaving it unused for some time best disconnect one
lead.

NOT a good idea on some modern cars.
The on board computer may loose it's program if disconnected.

Not heard of any car that becomes brain dead or confused if it any of
its computers loses power. The ECU may well forget the engine
settings but it will then load a basic "these will work" set and
relearn the engine over the next hundred miles or so.

Note "computers", a modern car has loads of the things. Very few if
any sub-systems don't have a processor of some sort
controling/watching over/reporting that sub-system. "Sub-system" can
mean a single door...

--
Cheers
Dave.