Electrical system shuts off; no lights, no signal light, no air conditioning, etc.

Have you had your battery or charging system tested? The electrical system in your vehicle is designed to shed excess amperage draw from accessories when there is a low voltage situation like a weak battery of charging system fault, this is done in order to keep your engine running and get you to your destination.

Here are a couple of guides to help:
https://www.2carpros.com/articles/how-to-replace-a-car-battery https://www.2carpros.com/articles/how-to-check-a-car-alternator https://www.2carpros.com/articles/symptoms-of-a-bad-car-battery