Shorted battery or short elsewhere?

Hi there, the car listed above has a 3.0 DOHC, I just finished a repair replacing all of the A/C lines. Which means I had to remove the coolant bottle and thermostat, the sensors and wires associated with that. Unplugging the radiator fan, A/C compressor, high pressure cycle switch, oil pressure switch, coolant level sensor, low pressure cycle switch, etc. While pulling a vacuum I let the car run to bleed the cooling system, and after about 45 minutes I noticed the car running badly and the windows did not operate correctly. The tachometer did not work, only the engine temperature and gas gauge seemed to work, and the airbag light was flashing and sometimes the theft light. Measuring battery voltage while the car was running, I got around 8 volts. With the battery unhooked I got around 12 volts. If I leave my jump pack on the battery the car runs normal and the tachometer works again. But I'm suspicious that the battery didn't just decide to die right now because of this repair. However, I did forget to unhook the battery before the repair. Any thoughts on this? Also, no battery light comes on.