Codes P0A80, PO318, U0100, U0111 Not Sure What to Do

I have a 2006 Prius and replaced the hybrid battery back in 2019 (June). I had an issue where I let the car sit too long earlier this year and the hybrid service repair person fixed the hybrid batter again and made mention of a potential issue with a 12V battery, causing lights and such to come on. I've bene driving my car regularly since then (and by regularly, I mean almost everyday for local runs as we a business where we ship items out every day/every other day). Recently while on a trip 17 miles away, every light came on including triangle of death, I have a code reader and got U100, U111, and the dreaded P0A80, I called my hybrid batter guy and he said it could be the ECM (I don't know what that is) but he could do a diagnostic. But with covid and timing restrictions (they have tight restrictions on when you can drop the car off) I've not been able to get the car to him. The next day I cleared the codes and it drove fine. When I turned the car back on, the only code that came up was P0A80, haven't seen any "U"codes since that one time. Today I cleared those codes and now car is giving P0A80 and P0318 still no U codes and the fan in the back passenger seat is coming on (but goes off when codes are cleared) . Wont be driving it anymore until I can get it seen by someone. Not sure what to do. Could hybrid battery be on the fritz again or could it be 12V battery causing this? How do I test 12V battery? Everything else seems fine. (I'm about as educated as a pre-schooler when it comes to cars so sorry if any of this sounds remedial!)

 

Thanks so much for responding. 191,028 miles. The hybrid battery has a 18 month warranty (ironically it expires in the middle of December). So I was wondering if that could have something to do with it. Will check out age and strength of 12v like you said! My repair guy is awesome, im lucky to have him. A small family owned business, local, doesn't over charge and honors warranties (at least so far, they have). Doesnt change thr fact that the hybrid batteries are rebuilt, which I figured. Worse come to worse I can sell it to them for parts or something but I'd like to do what I can to keep my prius. That thing has treated me so well!!

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