I charged both batteries (old main battery) for 6 hours and 2 hours later the old main battery, when tested at OReilly, was at 11.6V. Thats why I replaced it. I did not test the aux but it started the vehicle with bad battery so I assumed it was OK.
2023 Sport-S
My main battery has failed, so I replaced it today. While doing this replacement I pulled the F42 fuse and removed the smaller of the two ground cable from the main battery. I expected the auto stop start to then be inoperable. On my test drive the auto stop start engaged. What...