That dealer sounds like the problem A turbo goes at the dealer??? Come one now. Who would let a dealer test drive a vehicle for 1500 miles?? You have too much patience putting up with that incompetence, get a new one.
Auto start uses a lot of power, as do many systems on modern vehicles while parked. Use an onboard battery maintainer whenever you park. It will also extend battery life.
Once the battery is charged, the maintainer will keep it at 100%. There are so many systems constantly draining the battery. Like if you open a door, the LED fans run for a while. My previous 2014 F150 had the original battery when I sold it i January.
I have a 23 BB and use a Genus Battery Maintainer from Canadian Tire. It looks like yours. Make sure the ground is NOT connected to the battery, but to metal, otherwise the Battery Moniter System will be affected. Leave it plugged in whenever parked, all year because there are systems...
I am in Alberta. Alberta was the last jurisdiction in North America to use the reflective plates for police scanners. A cover over the plate prevents the scanner from reading the plate. A buddy here in the RCMP said it is technically illegal to cover a plate in Canada, but probably not...
Use a battery maintainer. Every new vehicle has a constant battery drain from multiple systems. Even an AGM will fail earlier if not charged properly. My last FoMoCo battery lasted over 10 years with a maintainer.