No permanent 12V - advice on secondary battery solution
I'm in a rather special situation : the car I'll be driving belongs to my company, and I'm not authorized to make any modification to it, so my carputer must be removable in 2 minutes without any permanent modification to the car.
Consequently, I indend to use a cigar-lighter socket to power up the PC (one of the cigar-lighters is on a 20A fuse). The problem is that this socket is not permanent : it is only powered when the engine is on. Without a permanent +12V, no clean shutdown can happen unless I have a secondary battery powering the PC while it is shutting down, right?
I am thinking of using the following circuit to power the PC, and wanted to submit the idea to you all...
Any advice/suggestion/warning is highly appreciated.