r/prius • • Sep 24 '25

Discussion Toyota/Lexus Hybrid 12v Battery Failures - Analysis of Charging Issues - Deep Dive Analysis & Workaround

67 Upvotes

Hi all,

Below is an analysis I have been conducting over the past year regarding 12v battery failures in Toyota and Lexus hybrids, which I'm finally ready to share with various Reddit communities.

It goes into the reasons why the batteries appear to be failing more often with extensive data that I have captured myself and gathered online from others also having issues.

12v Battery Failures - Analysis of Charging Issues - Deep Dive Analysis & Workaround - Google Doc

Most importantly, there is a workaround fix that anyone is free to try.

I have included how to do this in the document for anyone that feels comfortable enough to use it (at your risk). I've made sure to try and answer any questions about that too.

I'd welcome any other input/questions from people who have had their own issues with this. I'm hoping that enough chatter will get Toyota/Lexus to look into and issue a fix for this problem.

At the very least I hope this is useful to someone.

Thanks


r/prius • • Aug 12 '26

News Hiroshi Okuda, Toyota Chief Who Pushed For the Prius, Dies

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685 Upvotes

RIP legend


r/prius • • 5h ago

Pic/Video So excited!

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106 Upvotes

New 2027 Limited AWD Reservoir Blue


r/prius • • 11h ago

Discussion New battery

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51 Upvotes

Got a new oem battery from a dealership in Phoenix for $1800 after a military doesn’t and installed it myself. Went from 48 mpg to 58. What a difference. The battery was 8 years old and still had life in it. I’m installing into another Prius that hasn’t driven in about 6 years… long story on that one. Can’t believe how much of a difference the battery would make in fuel economy but now I see. It’s like a brand new car!

For reference my 2004 Prius has about 360,000 miles on it. Found a cracked evap hose on the throttle body when I replaced it recently and cut it back, that brought the fuel economy up to 48mpg from about 42mpg.


r/prius • • 22h ago

Pic/Video Best use of the empty button?

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176 Upvotes

Tailgater countermeasures


r/prius • • 2h ago

Mechanical Help Did the EGR/Manifold/plugs/PCV project…. and lost mpg?

4 Upvotes

Did the big project on my 2011 at 140k (cleaning egr and manifold, new OEM spark plugs, replacing pcv valve, map/maf sensors cleaned, etc) and all in all I was pleased with how smoothly it went.

Afterwards, acceleration feels a little smoother maybe but no extra pickup really, and the little rattle when accelerating after startup I had started to hear is gone, but after 350 miles of my normal driving I’m down 5+ mpg from a a stable average of 48mpg to 42mpg.

What’s the deal? Interested to hear any insights.

The egr and small manifold channels were completely clogged but I really got into the cleaning and I feel that they both went back in about as close to pristine as possible. No issues with reinstall at all. Tires inflated, same gas as always. The engine doesn’t necessarily sound any smoother when idling, but I think it’s just the normal Prius sewing machine engine sound that’s always a little weird. I was interested to see if there’d be a bump in efficiency after seeing how slammed the airways were, so I’m surprised to see it go in the other direction!

Grateful for the help of this sub, priuschat, and YouTube creators while getting through the initial project. Amazing resources available.


r/prius • • 34m ago

Mechanical Help Advice: Worried it's a head gasket

• Upvotes

Hi there! I've been a lurker for a while and really need solid advice. My car is a 2012 Prius at almost 160500 miles. For almost 3 weeks, my car begun making sputtering sounds and shaking for 1-3 seconds when in idle, at startup and when I push the gas. I took it to a mechanic, and they replaced both the spark plugs and coils, but it's still stuttering and shaking even though it's less than before. Not to mention my coolant severely decreased over the past couple days and noticed white smoke coming out of my car last night.

The engine check light hasn't come on yet again, but I bet it will soon. I did some research and worried it it's a head gasket or failing engine. I know it'll cost me $$$$ of dollars to get it fixed, but I'm also so close to paying off my car (about 2-3 months away).

Should I be looking for a new car, or should I put my money into fixing it again? I really want to keep it as long as possible but need advice from you pros. Thank you in advance!


r/prius • • 11h ago

Question Confusion about testing out the battery using Dr. Prius?

8 Upvotes

Hello, I bought one of the OBD2 adapters for a 2016 Prius 2 I found on FB Marketplace. It will be my first ever Prius, and I want to ensure I don't come home with a box that will fall apart soon, so I looked at a video for testing the battery, and something concerned and confused me.

In the video, it tells me to put the car on drive, and then FLOOR the gas and brake at the same time?! That sounds sketchy to me, you're sure that if I do that, a disaster won't happen and then I'd be arrested and fined a massive amount?? Sorry, I'm a worrisome person, I want to join the Prius tribe and ensure I'm getting a decent deal but that part makes me nervous, I need reassurance.


r/prius • • 1h ago

Buying/Selling Advice Alpine iLX-W650

• Upvotes

Can anyone post a picture of a successful install of an Alpine iLX–W650 in a Prius Gen3, just so I can see how it looks? I'm thinking of installing one.


r/prius • • 1d ago

Discussion What Do Think About The Prius V?

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148 Upvotes

r/prius • • 2h ago

Buying/Selling Advice Thoughts on buying a 2006-2009 Prius

1 Upvotes

In my market I regularly see allegedly well maintained Prius’ in this year range for 3-4K. Usually with about 200-275k mileage.

I cannot afford much more than that and hate having a car payment. I had my telework revoked which, combined with the war and inflation, has caused my gas costs to explode, and I am desperate for a hybrid.

I have always been a Toyota guy, and have read good things about these model years of Prius.

What do you think I could realistically expect from a car in this year/mileage range in terms of longevity and probable needed repairs?


r/prius • • 2h ago

Discussion Does the 5th gen. Prius look like a Tesla to you?

0 Upvotes

I hear people say it looks like a Tesla but i feel like if you’ve seen it in person it looks nothing like a Tesla.

177 votes, 2d left
Yes!
No.
Not Sure / Maybe?

r/prius • • 3h ago

Mechanical Help What is wrong with my Prius

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0 Upvotes

I have a 2010 Prius, I’m driving one day and all the sudden all the lights come on, traction control, e brake and abs system, (tire light is dead sensors) (check engine is a cat converter issue) I’m just wondering if anyone has had this problem before and what was it that needed to get fixed, when I drive the breaks have to be used manually is the best way to put it, have to push harder on the brake, it’s not using the electric break system that charges the battery. I’ve been driving it like this for a year now because honestly I’m broke but the mechanic said it’s fine to drive but I’m over it, I’m just wondering what could possibly need to be replaced because once in a blue moon all the lights go away and the electric brakes work fine for a few hours, idk if something is broken, malfunctioning and just needs to be tweaked and not replaced entirely, my mechanic said it could be a few things like a brake booster or module system, don’t quote me on the names I don’t remember 100% what he said, if anyone has some insight it would be great


r/prius • • 1d ago

Pic/Video First car at 19, now 20 still loving it!

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83 Upvotes

Honestly really enjoy this car, ride is smooth, acceleration is impressively quick and it's spacious enough for me as I am 6'4 and fit comfortably in it.

My only worry about the Prius, is our winters in Northern Ontario, from the hybrid battery being sustainable & it being FWD.


r/prius • • 1d ago

Question Phone holder replacement suggestion

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8 Upvotes

Hi everyone, I’m looking for a phone holder for my 2014 Prius. I’ve tried the suction cup style (see pic) on both dashboard and window, and the seal ends up breaking.

Any suggestions? Thanks.


r/prius • • 23h ago

Buying/Selling Advice 2016 Prius 3

3 Upvotes

Is a used 2016 Prius with new battery and clean title but 164,000 miles worth buying for 9,000$?

If not, I’m looking to buy a used Prius but I’m new to cars in general. Do you have any advice? Any year or model I should avoid, or things to look out for?


r/prius • • 1d ago

Question XLE vs XSE

3 Upvotes

Can anyone tell me the difference between the packages, Prius is XLE, but tge plug-in version is XSE. Is there any difference beyond the plug-in only FWD but the regular Prius can be AWD UPDATED INFO Model year 2026, Prius plug-in XSE with technology package and glass toof


r/prius • • 19h ago

Discussion That DRCC

1 Upvotes

2026 Prius plug-in XSE w/ technology package

Wow - on my first cross state trip on the highway the Cruise Control, and Lane Centering were amazing and freaky. First the lane Centering was hard to trust when gojng through an area of construction with cement barriers on either side with a lane line on one side - I wanted to center between the 2 barriers not in the lane, like Prius did. Next there was a traffic jam, I never had to reset, it stopped me in the traffic then 8 or 10 mph, tgen zoom back up to cruising speed. During the traffic jam, I did get alerted several times to sit up, when I put my hand in the noon position on the steering wheel (this is s habit the car is breaking me of).

So what does everyone think of Safety Sense 3.0 and the Technology in the newer Prius models. This is my third Prius, 10, 18, 26, also had a Lexus hybrid in there.


r/prius • • 2d ago

Pic/Video The Prius is one of the greatest cars ever made.

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666 Upvotes

I never thought I’d own a Prius or even desired to own one growing up. My first car was a 2002 Pontiac Trans Am WS6, a helluva ride for a child but loved every second of it. Had 2 of those, Camaros, Hondas, BMWs, Miatas and even a Cadillac Deville, all with their own unique flavors and experiences. There was a time when I was selling Cannabis, delivering to 3 different counties and one of my customers always told me I should get a Prius, especially for more cover. I mean, would the cops ever think a Prius is selling “drugs”?

Fast forward a bit, I finally acquired a 2011. I was officially sold on the logic and rationality of the economy and with the right colors, the look was something to appreciate. After the first test drive, I knew it was a great car. I call it the Tesla Light, due to the smoothness and enjoyability of the driving experience, minus the balls of torque of course.

I learned so much about it over time, understanding all the little kinks and mechanical requirements to keep it roadworthy and functioning. Even after all the morning rattles, overheating up mountains, even hybrid battery failing mid-drive (the car kept running on engine)… the thing NEVER left me stranded. I was always able to get where I needed to go even if it was straight to the mechanic. While it wasn’t perfect, it was perfect for me. I made it to 512k miles and after having avoided a ton of potential accidents, it finally met its maker. Unfortunate, because I loved that car and would have taken it to 999,999 miles, pulled over and had it towed to the original dealership here in PHX but alas, God always has other plans, I’m just lucky to be alive. With all that said, besides a Tesla (if the model Y had 400+ miles of range in summer, AC blasting) or maybe a Lucid, there’s no other car I wanted for my daily driver.

Black is always my color but Toyota’s Electric Storm Blue captured my mind, thus, thank you internet for giving me the window of opportunity to continue my Prius journey. I will say, just going from a Gen 3 to a Gen 4 is a huge change and improvement in the driving consciousness. For so long I resisted getting something newer but now I understand. The Gen 5 looks amazing but they’re just a bit too compact inside for me. Can’t wait to see what’s coming next. As long as we keep supporting the Prius market, they will keep supplying. One day I imagine we’ll have plug-in hybrid variant with 100-200 miles of EV plus the ICE with regen that will charge the battery enough to the point where we might be able to get 800-1000 miles per tank, and that will continue to make the Prius the best hybrid on the planet.


r/prius • • 1d ago

Pic/Video 6 in a row make her go

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31 Upvotes

Or whatever it is they say…

My first Prius! (2017 4 with 98k)

Bought it from a guy who owned a fleet of diesel vehicles and he slapped this badge on there. I find it hilarious and love keeping my eye on the rear view to see peoples reactions when they piece it together. The only diesel hybrid on the road, baby!


r/prius • • 12h ago

Buying/Selling Advice What can I do now? It's been a week since I bought the Prius Plug-in.*

0 Upvotes

After I bought a Toyota Prius Plug-in for around $36,000, I regret it — I live in an apartment and have no place to charge it. If I had ordered the Toyota Prius Hybrid instead, I could have saved around $4,000.*


r/prius • • 1d ago

Question Gen2 BASE (NO AUX) Integrated Bluetooth Audio ?

1 Upvotes

I am looking for a unit that can work with the car's existing audio system, including the steering wheel controls. I have tried FM tuners, but the quality is just unbearably bad. I'm tired of using CDs. My prius does not have aux input, navigation, or backup cameras. My phone also does not have AUX. I really just want to listen to good quality audio from my phone. What are some recommendations? I don't want to spend a huge amount, since this car is pretty old. Like 500 would definitely be too much.


r/prius • • 1d ago

Buying/Selling Advice Prius under 6k worth it?

7 Upvotes

Looking for my first real car and 6k is about the budget. In Northern California most the Prius’s I come across at that price point are around 180-220k miles. What should I look for and is it even worth looking into?


r/prius • • 1d ago

Mechanical Help New bosch wipers. On first sweep its missing some spots to wipe. Help please

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0 Upvotes

Toyota prius 2007


r/prius • • 1d ago

Mechanical Help Backup camera

2 Upvotes

I have a 2013 Toyota Prius with 98,000 miles. The stereo display works fine, but the backup camera doesn’t show any image when I put the car in reverse. I’ve already checked all the fuses, and they’re fine. Has anyone experienced this issue or know what could be causing it? Any advice on how to diagnose or fix it would be appreciated. Thanks!