2012 Prius - light up but won't start motor or drive

Hi y'all. Newbie here - need your advice. There are many posts about my problem, where all Prius lights light up but neither the car move not the engine starts. I'm going to replace the 12v battery first (it's ~150k on the car and I suspect it was the original battery all along). Seems like the consensus is to use the OEM battery. I checked on parts.toyota and it looks like I have two options here:
TrueStart Battery, P/N: 0054421171325 and some generic vehicle Battery, P/N: 2880021171. The latter is a tad more expensive. Other than that, I can't find much info on either; specifically, which one would be the best choice. Can anyone weigh in and explain the difference if any? Also, is it recommended to order parts from dealers using parts.toyota website or is it better to call 'em first? I passionately dislike and distrust dealers so any chance to reduce interaction would be great. Are there any other tips to make sure I'll get what I expect to get? Lastly, aside from the 12v battery, is it recommended to replace keyfob battery as well? I remember that before the car died, it sometimes warned me about the small battery charge being low, despite I changed those bad boys regularly (I mean, maybe there is another reason for that warning).
Thanks a ton in advance - this is really a bad time for breaking (when is it good?) and I really need my car back asap.


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My attempt to write this post using ChatGPT - quite funny yet on point:

Once upon a time, there was a 2012 Prius that belonged to a young couple, named Jack and Jill. They had owned the car for a few years and had been very happy with it, but one day, as they were about to leave for work, the car wouldn't start.

They noticed that all the lights were on, but the engine wouldn't turn over. Jack and Jill were puzzled, they had never had any issues with the car before. They tried to jump start the car, but it still wouldn't start. They decided to call a tow truck to take the car back home.

Once they got back home, they did some research and learned that a common issue with Prius models is a weak or dead 12v battery. They realized that they had been experiencing some issues with the 12v battery for a while, such as the radio and the lights turning on and off on their own, but they had ignored them thinking it was just a minor inconvenience.

They decided to replace the 12v battery and take the car to a mechanic to have it checked over. The mechanic confirmed that the 12v battery was dead and needed to be replaced. He also found that the 12v battery had been draining the main hybrid battery and that was the reason why the car wouldn't start. The mechanic replaced the 12v battery and also performed a full checkup on the car.

From that day on, Jack and Jill's Prius ran smoothly and they were able to enjoy their daily commute without any issues. They learned an important lesson to always pay attention to the small warning signs and to have their car regularly serviced to avoid more serious problems in the future.

 

thanks for the response! The 12V battery was dying for the past year or more - I had to jumpstart the car every now and then, lately even without any obvious reasons (like, kids forgot to turn off the interior lights). So the battery is bad and has to be replaced anyway. Would you recommend a particular brand for this version/trim of prius that is better than OEM?

Thanks for weighing in. The draining piece was generated by ChatGPT (robotic answer essentially - thought it'd be funny to share. sorry, didn't mean to derail the discussion). Yes, I will replace the 12V battery anyway. Do you know the difference between the two batteries in my post? Two different part numbers are listed on parts_toyota_com as compatible with my Prius 2012 - I want to understand which one to buy. The cheaper option actually looks better (extended warranty and such) and that's why I'm confused.

thanks for your response. The car does not go into the "ready" state, but neither it shows the triangle of death. I don't have a voltmeter, but the 12V battery has been an issue for a while so I will replace it anyway. As I mentioned, I suspect that it might be the original battery that's 10+ years old. The problem could span beyond replacing the 12v battery, though. Sporadically, I was getting a message to check the hybrid system - went to 2 dealerships and they never could find any problem so they just reset errors. Didn't impact driving as well, so I don't really know. The reason I mentioned that is because 2 weeks before the car started to behave like this (lights on, nothing else), I've got that error popped up again. Could be related.

 

Thanks for helping. I can't justify spending ~$50 on a device that I would tell me what I know and that I likely won't need again. However, I happen to have a regular Chinese multimeter like this one amzn - B08DHHJPS1 (can't create links; not this model but same form-factor). Would that work?

yes, ordered OEM from a dealer nearby via Toyota website for ~$160 - looks like a good price.

Never heard of those - thanks for educating me. While consumer electronics definitely benefited from the introduction of li-pol batteries, I'm a bit skeptical if those are as reliable and long-lasting as AGM/lead batteries. Will research that!

yeah, that context was in my head but I forgot to share.
How would I charge a car battery at home? I don't have a battery conditioner or alike.

 

Want to update y'all - today I went to remove the old 12v battery for recycling. The car was completely dead but I needed to open the trunk. So, I jumpstarted it again but noticed that the key could not be detected. Then after a few attempts I finally opened all the doors and removed the battery. While doing so, I noticed that the hybrid battery orange lock was a bit misplaced, so I put it back in place. Finally, once finished, I needed to lock everything, so I jumpstarted the car again (without the 12v battery). And, surprise, it started! I drove it for ~20 min just in case.
So, it looks like stars misaligned so that keyfob battery died, 12v battery finally dies too, and the hybrid lock was misplaced - all at once, causing such an entanglement (plus a few forgotten cans of coke exploded when the temp fell below freezing, but that's another story). Now at least I have some confidence that the car is still alive more than not.

PS: I also realized that one of the headlights does not work. Inspired but partial success, I'd like to replace the bulb by myself - is that doable or do I need to replace the whole assembly?

Thank you so much guys for helping me out!

 

Reporting in - a couple of days has passed and so far, my little hybrid turns on without issues (I replaced the 12V battery with a new OEM, and also replaced the key fob battery). Still need to replace the headlight bulb and clean the coke mess (tho, I'm thankful that it was a can zero sugar coke).
However, the check hybrid system error came back on the second day. Not sure if it's coincidental or triggered, but I pressed door unlock button and immediately the message popped up on the screen. Anyhow, this error is nothing new - it came 2-3 times in the past and every time dealers couldn't find a problem and just reset it. I can drive the car normally tho (first time I was scared, not I'm annoyed). Nonetheless, this is still concerning and I'd like to solve the root cause. Here is the exact message (not mine, but aside from mileage, everything is 100% the same. My car has 155k).

Can you please recommend the best course of action to pinpoint the problem? The fact that dealers couldn't identify any problem leaves me with little hope for resolution but at least I can try. I already found a recommendation to clean up the battery fan as one of the ideas.
Please let me know your thoughts. As always, thank you so much (also, let me know if you think that this deserves a separate post).

 

Thank you sir - ordered both types from Amazon - let's see which one is better and send back the slacker. Will update the post in a week.

 

actually, I did that. I do have the report somewhere - let me find it. It's been a couple years (sheesh, time flies) since the previous occurrence tho, so I'd still need to obtain the latest info since the cause might have changed too. Thanks for the idea - I'll report back.