2007 Red triangle, check engine, car with exclamation point, car runs fine

Hi everyone. I haven’t seen my exact issue after searching so I’m posting. I bought my 2007 Prius almost 3 years ago. A few months after getting her, I backed into a car (not hard and no damage) and after that, the battery levels started acting funny when it was hot outside. Never a problem when it’s cold so I just went in my merry way. Air conditioning stopped working last summer but still just kept going. We take her in religiously for oil changes and tire rotations too. Two days ago, the red triangle came on, check engine, car with exclamation point. It’s very warm here now (almost 90). After starting, the battery level drops down to red pretty quickly when idling, but charges back up after driving a short distance (less than a mile). Then I can idle without the charge dropping. I tried an OBDII reader and received no codes. Checked the rear fuses for inverter and battery and they are good. Checked battery fan fuse and it’s good. Im really hoping this is the inverter cooling pump and not the hv and wanted to get other opinions before I take her to a dealership. Did I mention she has over 284k in her? Please help me figure this out!

 

Thank you! I’ll try that!