Originally Posted by Fountainhead

I changed my battery and connected a trickle charger to the bat wires when removing the other one, and put the new one in and voila! No data loss.
Of course they sell those little dongles that plug into the OBD port that are hit or miss on keeping the ECU/ECM powered up during no battery time.
Changing my battery took about 20 minutes counting lovingly coating the battery terminals with dielectric grease and putting those cute Red and Green useless battery corrosion inhibitors on there....plus cleaning out the battery tray trash, etc. Plus lovingly cleaning the gasket surfaces of the windshield plastic piece and the windshield in that area....OCD I know.