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Gen 2 Toyota Prius Lithium-Ion Battery Back Replacement Update

For those who are interested in knowing more about the test pack. I have some news for you.


Yeah, I may have created an enormous stir about a lithium-ion pack replacement for the Gen 2 Prius, but honestly, it was worth it. I am not here to brag about it but to give you insight into why I like the idea.

Here is what I can tell you about it and give some hints about what it may cost you to get one in the future.

Why I Like The Lithium-Ion Replacement Pack For Prius
As the Hybrid Guy, I love all things hybrid. My favorite hybrid, by far, is the Toyota Prius. I have now owned 13 total hybrids, 10 of them being Toyota.

I favor the second-generation Prius (2004-2009) mainly because the cars are little tanks. Usually, people sell them for cheap when they have problems because they can be expensive to repair.

Toyota Prius Nickel Metal battery blockMost repairs on the Prius I have found are cost-effective and straightforward if you are a handy DIYer. Many times though, the owners are tired of them and want something newer, so the price drops, and I can pick them up for cheap.

After a few fixes (and usually a thorough cleaning), I can get them back on the road for pennies on the dollar. I always learn everything I can with the car, do all the maintenance and then resell it. This has allowed me to work through many issues and develop less expensive ways to repair these cars.

One of Prius owners' most common issues is the dreaded aging and death of the original traction battery. By now, the battery packs have either been replaced by lower-quality refurbished units or had some genius replace a bad module without the proper conditioning.

At some point, we should get a better battery for an older car. Yes, and that is where this prototype battery comes in.

Another reason I like the idea of going to Lithium-ion is that it is well-researched battery chemistry. Significant advances have been made to produce a better, lighter, and more energy-dense battery.

If you could double the EV range of your Prius, would you do it? If you could see a 5 to 7 mile per gallon increase, would you want it? If you Prius was more responsive and quieter, would you do it? Of course, you would.

What I See With My Prototype
I can tell you what is happening with my Prius after installing the new battery. MPG went up by 5 miles per gallon. Stops and starts are much smoother. My test Prius is a high mileage one with 208,000 well-used miles. The EV range is impressive on it too.

Toyota Prius fuel use monitor system

Now I am getting into colder temperatures here in the pacific northwest, so I know that this is only the start of a beautiful relationship. Once warmer weather "springs" back then, I am sure I will have more to write.

What Is This Battery Going To Cost?
Cost is the question that I think everyone wants to know. Here is what I can tell you about lithium-ion production. It is improving at a rapid rate.

Tesla recently came up with a new way to produce lithium cells that is cheaper and more energy-dense. Have other companies that produce lithium cells started to follow suit? I cannot say for sure. I can tell you that the costs have come down significantly.

If I were to wager an educated guess, I would say that replacement lithium-ion modules would cost between $1600 to $3000 for NEW, not used, replacements. That, of course, may or may not include installation.

The second factor here is also how many of these things can also be produced. The more that can be made usually the less it will cost to manufacture. So if there is an order for a million modules, I hope we can see a better end cost for the consumer.

There are going to be many that disagree with me on keeping an older Prius alive. I like my car and to have an option that gives it an updated feel and performance. Yeah, I am going to do it. There are loads of others out there who want to keep their Prius around for as long as possible, so I am confident they would like to do it.

The haters will say, ditch the car, ditch the idea, throw it all away, and lithium replacements are useless. They will say there is no market for it and blah, blah, blah. Well, whatever, there is a huge demand for better replacements, and they are on their way, so watch out for them.

Have a great week, everyone, and I will see you in the next story.

Fix Your Toyota Prius P0420 Catalyst Efficiency Code For Less Than $20

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.


Jim Hopkins (not verified)    November 12, 2020 - 9:04PM

Thanks for the update, and all your other articles as well. I'm a lifelong shade tree mechanic, and following your Prius maintenance and repair advice for my current 2010 Prius and previous 2001 model has definitely resulted in improvements in my car performance. Much appreciated!

As the owner of a 2010 Prius, I find the Li-ion idea to be interesting, assuming the cost would be close to the same as for a replacement NiMH battery pack.

But I wonder about the charging circuitry, since charging requirements for NiMH batteries are typically different than for Li-ion batteries, at least in the non-automotive world. Can the existing charging system, especially in older models, properly handle Li-ion batteries, or would it also have to be upgraded?

When my OEM NiMH battery pack started showing signs of degrading about 5,000 miles ago (at 192,000 miles), after reading up on some recommendations and reviews, I decided to take a risk and bought a Prolong reconditioning package (charging and discharging units), which runs about half the cost or less of the various reconditioned and new replacement non-OEM battery packs that I found available.

I've only done one round of reconditioning so far, but it worked exactly as advertised, and the battery pack appears to be fully restored to new or nearly-new performance levels, and the performance of my car is back up to par. I'm now an official fan of Hybrid Automotive (the company who designs and makes the Prolong equipment) for sure!

If this diy reconditioning process continues to work well, keeping this same battery pack going for, say, the next 50,000 to 100,000 miles or so, then that would definitely reduce my interest in the Li-ion idea.

Also, though I'm not in an area with severe winters, I understand that NiMH batteries can possibly be a better choice than Li-ion from a performance standpoint in very cold winter climes. I think I remember reading somewhere that the AWD Prius uses NiMH batteries instead of Li-ion for this reason. Any thoughts on that?

Thanks again!

Felix Calles (not verified)    November 20, 2020 - 1:18AM

Hello. I am new in this place. I found very interested idea about converting second generation prius to lithium. I own a prius shop in los angeles area. We are starting to test lithium batteries in third gen prius. So far so good.Prius are responding much better, mostly gas engine stop in every red light. Mpg increase a little bit, but with a high mileage prius, there are many factors to consider in order to get a much better mileage, like engine conditions, catalytic converter, oxigen sensors, injectors, etc.the idea of replacing Nimh battery for lithium is really possible. We will continue testing before offering to customers.

Christa Conley (not verified)    December 29, 2020 - 12:04AM

I own an 07 Prius and I love it. It has 234,000 miles on it and I'm concerned about the batteries. Also has a tick in engine but had a mechanic tell me it's normal for the mileage I've thought about getting a different car but mines paid for. What are some options for me to keep my car going for another 234,000 miles?

Shane (not verified)    March 17, 2021 - 2:50PM

I own a 2008 Prius Gen 2 and am living in South Africa. I have owned many German "performance" cars and currently drive a BMW 3 series. The Prius is my daily driver and I cannot help but be excited by this news. To say that this car is a tank is quite correct.
There has only been one issue so far:
I have been struggling for a few years with a heater that won't work. The aircon is fine but the heater just won't heat.
They have changed the thermostat but still no luck.
Any ideas?

Fred G (not verified)    April 12, 2021 - 7:54PM

My 2007 Prius is ready for Lithium batteries. I'm in Alameda, California. Any shops there that can help?

Paul Bergeron (not verified)    May 21, 2023 - 6:02PM

In reply to by Fred G (not verified)

Did u replace your nimh battery with lithium-ion? How did it go. I have a 2007 that I tried having a guy replace a few cells but I’m back at square one after just two months, need to replace the battery. Think of doing so with the lithium-ion bersion

JP EASTRIDGE (not verified)    May 14, 2021 - 7:08AM

My 2007 has over 300,000 miles on it, and the pack went bad only because I stopped driving it after changing jobs.
I did not discover the pack was bad until after I replaced the struts (original), brakes (original) and other worn parts. Fired it up, and it gave me the dreaded triangle of danger!
Now I need to keep it parked until I can replace that pack. The new Lithium pack sounds perfect! I would be willing to provide all driving data on a high mileage second gen Prius, for a shot at that pack.