I have a 2009 1 series with Idrive and am contemplating doing a couple DIY tasks (i.e. alarm, audio) that will require me to disconnect the battery. My question is what does everyone do/use to keep from losing settings/prefs? Do those 9v "settings savers" work? or would I have to connect a battery charger to the terminals in the engine bay? Thanks in advance for your advice/suggestions.