12V low warning light on, Toyota says battery fine. Help!

A few weeks ago, while sitting in the parking lot at work, my 3rd generation 2015 Prius’ radio conked out. Tried another channel and found all the stations were out. Turned the car off and then turned it back on to accessory. It beeped at me and said the aux battery was low and to make sure I was parked on a level surface (which I was).


This is my third Prius. Previous 2 (1st & 2nd Gen) had their 12V batteries die after the dash kept fading (1st Gen) or giving me a message about my transmission malfunctioning (2nd Gen) at the 2-3 year old mark. ACcording to dealer, low 12V means weird messages. Oddly, once changed, the new batteries lasted longer than the originals and didn’t need another change.


So when my 2.5 year old 3rd Gen gave me a real “it’s the battery” message, I was thrilled I didn’t have to decipher what was going on. Took it to Toyota, relayed the problem and my past experience so they knew why I was sure it was the 12V. For 2 hours I sat, thinking they were replacing it, for them to tell me it was fine, the battery was giving off more charge than it should and that if I ever saw that message again I needed to take my car around the block. Ok, but it was December in PA and with the memory of my dead in Feb Prius in mind, couldn’t we just change it anyway so I didn’t have to worry about it? Nope. I left wondering if I’d be stranded in a few weeks or if I got ripped off when they automatically changed my 2nd Gen based on the same signs.


It has been near zero at night for 1.5 weeks here and below 20 most days. I made sure, even while off for the holiday, to drive my car around. Yesterday it was fine. It started fine this morning, then all the electronics died in the parking lot at work. Turned it off, tried to put it back on accessory, dash flickered, gave the low 12V message. Tried to start the engine and the engine wouldn’t start. Waited a minute, tried to start it again and it ran. Went back out 2 hours later at break and it started fine. I drove it around the block at work.


I really don’t know what to do. Toyota refused to change the battery, I can’t walk into Walmart and buy one for my stepdad to replace. This is causing me daily anxiety in the super cold weather. Do I take it back to Toyota and insist they replace the battery? Could it be something else wrong with it like an electrical problem? Any advice on what it might be or what I should do is appreciated.

 

Thank you. I will look into that.

I drive it daily but work is 10 minutes from home.

 

I work close to home. My previous two needed battery replacements early but once replaced lasted for as long as I had the car.

 

To clarify I never once thought the 12v was under warranty. By replace I meant that after I sat in their waiting area for two hours in the middle of a work day figuring that amount of time meant they were putting a new battery I expected a bill for $200+ not "drive around the block when You get that message", its fine and we aren't changing it for you. When I took my Gen 2 Prius in for a similar message they were all over it telling me I needed a new battery, changed it and I never needed another for the following five years I had the car. I wanted it taken care of before it was 10 degrees out. A month later it is acting up again and nothing has changed about how I treat it and until Thanksgiving I never had a battery issue.

I do not sit for long periods listening to the radio in accessory, maybe five minutes, and in my post said I just turned the car on accessory that day to check the time. But honestly people do do this with cars and I have done it with my previous Priuses. If I can't treat this Prius like most people treat a cat my next car probably won't be one, sad because this is my third.

My step dad says he isn't comfortable doing the replacement so I will either try a Pep Boys or AAA since Toyota was a waste of a day.

Thanks for helping confirm it is the battery

 

Not sure where you got that I sit for "long periods of time" in accessory but I don't. About five minutes a day I have it on accessory before going into work. Most people do this with their cars no prob. That is not abuse. I never said I thought it was defective or under warranty either. I was concerned it might be an electrical prob since Toyota said the battery was fine yet I still keep having issues that I previously did not have with the car until this November.