The battery tender jr may be small and not look like much. But it works. Eventually. I'm assuming the replacement AZ alternator is ok. Because its the same issue that had me assuming alternator in the first place. Voltage not running, no key, 12.30v. Start up and idling, voltage takes a dip to 11-11.30v. So its not charging with a new alternator.
Its had an engine swap by PO. Could a missing ground cause an issue like this?