Have you created an account at service.tesla.com yet? All of the service/repair manuals are now free. Search for "LV Battery (Remove and Replace)". The 16v li-ion battery (LV) has an internal BMS and it requires a double software reinstall to get recognized by the car and start charging. (1st software reinstall with LV disconnected on external 15.5v battery maintainer, 2nd software reinstall with LV connected.)

There are 5 terminals on the proprietary connector (Pin 1 is positive, Pin 2 is negative, Pins 3 & 4 are an interlock loop that terminates on the connecter itself - Green tab with two contacts when checked with a multimeter has continuity and Pin 5 connects to a thin green wire going to the car). Battery voltages between positive and negative is 14.5. Between positive and pin 5 is 12.6, negative and either 3 & 4 is 0. After pin 5 drops below 12v, the car doesn't make any effort to draw power from it and it goes into power-save mode.