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Refresh Your Old Toyota Prius With A New Li-ion Battery Pack

Remember me hinting at a LiFePo hybrid battery replacement? I got the OK to give more information out about where we are in testing and potential production. Take a look.

A while back, I wrote an article about a potential lithium-ion replacement battery pack for Prius. This article will cover what I can tell you so far about the proprietary system and what you can expect.

Why Has Toyota Not Used Lithium Ion?
Toyota now does use lithium-ion; they used only nickel-metal though for a long time. As someone who has studied battery characteristics for a few years now, I can tell you that nickel metal is a thing of the past.

Once hailed as "the solution" to the Nickel Cadmium problem, we now know Nickel Metal suffers from a similar but less severe. Nickel Metal has been a bridge technology that has seen plenty of research time and can now be laid to rest.

3rd Gen prius battery

For the longest time, Toyota would not use anything but NiMh because they felt Li-ion did not have "enough research" to understand the technology entirely.

They were right in many respects and kept using their proven method for nearly two decades. Then Toyota finally accepted Li-ion in their most modern hybrids and use it almost exclusively today.

But what does this mean for older aging Prius that are still on the road and loved by millions? Here is the answer to that question.

New Tech To Refresh Your Old Prius
When I caught wind that there could be a better replacement battery for the aging Prius, I had to know more. I found out who was doing the prototyping and got a hold of them.

The battery builder told me that we could not reveal anything about the battery other than it was a test to see how well this tech would fare in the real world.

2010 Prius battery installed in the rear

I was excited and swore that I would keep this under wraps as much as possible, which I have. The good thing is I can now tell you more about it.

The battery I have for testing is a module replacement for your existing battery platform. I removed all the old (and heavy) nickel-metal modules and replaced them with lighter and newer Lithium-Ion modules.

I noticed that the battery had far less weight by a good 40 to 60 pounds. The Li-ion is significantly lighter. The test boxes that hold the new battery tech allow only one side of the busbars to be used, making installation relatively easy.

My battery was a little challenging to work with where I had 3D printed module boxes, but I made it work overall. I can tell you that the go-to-market batteries will have a better design and will be easier to use. This brings up my next point, when could we see this go to market.

I do not know when we will see this going to market, but I can tell you it is in progress, so I will give you more info when I know more on that.

I used the battery on my well-aged 2008 Prius. I was getting 39 mpg before, and the car did not go into EV. Now I get 47 miles per gallon, and I stay in EV range for almost 3 miles when the battery is charged fully.

The combination of a more energy-dense battery and lighter are two significant contributors that will boost your MPG. So far, I can tell you that the conversion is safe (3000 miles driven now), and it will breathe new life into your old Prius.

Any questions? Please find me on Twitter @the_hybrid_guy. I am happy to answer what I can about these conversions. That is all for today; I look forward to seeing you in the next article.

Question: Can one module be replaced in the battery pack? Click here to find out.

Check out this wild new battery tech that Tesla has and why it will forever change the auto industry.

Peter Neilson is an automotive consultant specializing in electric cars and hybrid battery technologies. He holds a Bachelor of Science in Automotive Service Technology from Weber State University. Peter can be reached on Linkedin and you can tweet him at The_hybrid_guy on Twitter. Find his page on Facebook at Certified Auto Consulting. Read more of Peter's stories at Toyota news coverage on Torque News. Search Toyota Prius Torque News for more in depth Prius coverage from our reporters.


Eric Sheikh (not verified)    June 9, 2021 - 11:07AM

In reply to by Michael Brunner (not verified)

i thinks its between 1600 and 1900 .. it depends on the dealer / redistributor available .. this is comprobale to a reman nimh pack so .. no brainer if u can get one .. and your car is worth keeping ..

e (not verified)    June 9, 2021 - 5:10PM

In reply to by Eric Sheikh (not verified)

if your acar is worth keeping .. if u got over 175k miles on it and alot of other issues .. u may reconsider .. next thing to go is the ABS accumulator/pump .. that is no small replacement .. it makes the traction battery replacement seem like walk in park ...

Lawrence Jones (not verified)    February 23, 2022 - 8:04PM

In reply to by e (not verified)

Well, I have a Honda Insight, aka the one to beat. I have 300k on mine and no rust because it's all aluminum. Underneath parts are still metal but clean. We get easily 400-750k miles before issues come up and while it's a 2 seater, I'm an amateur hyoermiler getting around 83mpg 70-78 in mixed traffic. Point of this story? MAKE THEM FOR INSIGHTS TOO. PRETTY PLEASE.

Halina Kuta (not verified)    February 24, 2022 - 3:44AM

In reply to by Dennis (not verified)

Hello, I owe Toyota Prius C 2012.. low mileage 39.500
I would like to replace batteries .. I need your advice from your knowledge when I can or should do it ?
Your article is very interested ! I like!
Halina Kuta

Tracy (not verified)    June 10, 2022 - 2:37PM

In reply to by Richard Kotey (not verified)

Greetings! Very helpful advice within this post! It is the little changes that will make the greatest changes.
Thanks for sharing! donate for ukraine

Jose (not verified)    February 27, 2021 - 5:50PM

Current EV's that utiize Li-Ion all have complex coolant systems that maintain the Li-Ion pack at a certain temperature range. This is one of the main reason's Toyota did not adapt this battery chemistry. The added complexity goes against the philosphy of rhe Prius drive system. Checkout the Chevy Volt forum for the issues they are having now with their Voltec system as an idea.

Jimmy Yow (not verified)    February 27, 2021 - 10:55PM

Great news and info. Just wonder if you could help me. I have a 2013 Audi A6 Hybrid and wonder if there is a compatible battery replacement available in the market like lithium ion pack. Appreciate any comments in sourcing the replacement pack. Thank you very much. Jimmy Yow

Brandon Hignett (not verified)    February 28, 2021 - 1:20AM

I have a 2009 prius which is going well. But will like to be kept updated for when I need a replacement

Ivan F (not verified)    February 28, 2021 - 11:01AM

I didn't see any mention of whether the battery management needs to be altered or if that's something that came with the package. It's exciting since my Prius has 183 thousand miles on the clock and I've been getting 35mpg due to the cold... I'm prepared to replace the traction battery if needed but if I can upgrade instead that'll be great. I was thinking that one could buy a Prius Prime traction battery and swap it into an older Prius but that's not cheap and I have no idea whether it bolts in or not. Apparently all Primes shipped with Li-Ion which handles plugin charging better or something? I don't know.

RoseMary Mathis (not verified)    February 28, 2021 - 1:51PM

My Prius is 2012.. My gas mileage went down from 46 mpg avg to 39 mpg after a prob where my car shut down and a factory warranty repair was done. I was told that should not have had an effect on gas mileage .. The car also started using oil with that repair .. I'm wondering if the adjustment in the repair would have caused the motor to be used more and burning oil more.. ? It seems that incidence did something ? I'm not very impressed with local Toyota service departments within 60 miles of me..

Mike B (not verified)    March 2, 2021 - 11:57AM

You did not go from 39 to 47 MPG because the battery is lighter and more energy dense, while yes lighter does help 40 to 60 pounds is a few bags of groceries, otherwise you would see massive losses when driving with another person in the car. No, you got a huge boost because your battery pack was old and couldn't hold as much charge. This is something that may be fixable too if it's just due to some dead cells

Leif (not verified)    April 12, 2021 - 12:57PM

This is exciting news. My '09 GenII has over 260,000 miles and while it is indeed old, I see no compelling reason to replace it. I've long believed that Toyota's BMS is both conservative and comprehensive, which is why so many Prii are running around with their original batteries. I have to assume that the Li-Ion pack's builders have taken the existing BMS' behavior into account so their batts play well with Toyota's brain.

I'm averaging about 49.6 MPG right now, shedding a few pounds and adding more EV capacity for the in-town driving my wife does could only improve matters.

Terry Robb (not verified)    February 24, 2022 - 7:19AM

A real waste of time. Better to buy a new EV than waste time on vehicle with 100 HP motor. A new EV will have way higher charging capacity. A lot of Prius owners went to model 3 in CA

D Lewis (not verified)    December 6, 2023 - 2:36PM

In reply to by Terry Robb (not verified)

Huh? Spend 40,000+ or a few thousand and it's a better deal? Exactly what does 100 HP have to do with anything? The owner of the Prius knows their use case because they already have long term experience with their current ride. It's always easy to spend OPM (Other People's Money).

Jay (not verified)    July 11, 2022 - 10:16PM

I have Prius 2010. How can I upgrade it's battery to Lithium Ion? Also, is this upgrade approved by the manufacturer?
Thank you.