Are you calibrating your runs in the portal? This seems pretty unusual if you have more than 5 runs and they've been calibrated.
This doesn't seem likely unless for some reason the pods were detecting foot strikes while you were driving. There was a member of the community that had post run recording through movement on a piece of fitness equipment.
Were you continuously walking, or just sort of milling around?
This sounds like you're seeing the battery indication wonkiness that was common a couple of months ago. Have you updated to the 8.54 firmware? A good quality battery like Energizer will go for 12-14 hrs, and the lesser quality generics should go for at least 8 hrs. If you are still running an earlier release of the firmware, it will give you a false low battery indication even though the batteries have plenty of power.