I need to replace the battery in my E46 M3 'vert. Rather than making a trip to buy a battery and a return trip to bring back the old one, I'd like to do it in one trip in my daily-driver. That would mean the battery would be disconnected for 1-2 hours minimum. Can I hook up my Battery Tender to the under-hood connections to keep the car "powered" during this time? Do I even need to? My concern is leaving the car with no battery at all for hours would cause loss of settings/memory or some other detrimental effects. Normally a battery swap would only take a few minutes.