Bought this Prius used about 6 months back. Excellent condition withy 113K miles. (June 2021) I vaguely remember the seller saying, he installed new 12v battery just few months back at the Toyota Dealer. By Dec 2021, the mileage is 120K now. works smooth no issues. Just 1 week back in quiet cold in NC, and I left headlights on for few hours. The 12 v battery dead. it started quick with a jump start. Worked well for 1 week. again, yesterday the inside lights were on whole night and car was outside in cold. By morning battery dead. I removed the battery and charged it full. It is working good now. I noticed the sticker 160512w. That means 16th May 2012 is the manufacturing date. so either the Dealer lied and charged him for battery. Or the seller lied or forgot. (The seller was so organized with all the receipts, that I am less likely to believe seller lied. He even gave me few latest receipts. I will have to dig in to them) Eitherway...I am very very surprised to know that this battery lasted 9 years and 120K miles.
Seems like they didn't replace the battery. If you have the receipts, take it to them and get a new battery. You are certainly due for a new battery though.
You can (probably should, if you've already discharged a battery once because of it) set your headlights to turn off automatically in a submenu somewhere on the stereo head unit. Factory default is to turn off after 30 seconds IIRC, but a previous owner may have changed it.
I have the syncup drive from T-Mobile for data in the car, it plugs into the diagnostic port for power. It also watches the car and texts voltage. Towards the end of last winter when cold I'd get some readings saying it was dipping below 12V and to look for a replacement soon. Over the summer it worked just fine. This year when it got cold they returned and much quicker and frequently. I replaced the battery, which is very easy to do FYI, not sure why auto parts stores won't do them like they do for everyone else. Regardless I got a Napa battery. I also was still driving on my original battery though I knew this, 2013 160k miles.
if they can't pop the hood, remove two terminals, remove the battery, put the new battery in and reconnect the terminals, they're not interested. and most dealers gouge their customers for the prius battery replacement labor. they all make a huge deal out of lifting the hatch floor, and the vent tube and blah, blah, blah
