I have been told by Prius owners and mechanics that the hybrid batter will eventually fail between 150,000 and 170,000 miles. My battery failed at around 185400 miles, not too bad, but I have heard that hybrid vehicles used for ride-share and taxis last much longer. Now, I did use my vehicle for ride-share for over 100,000+ miles and may have contributed to it lasting as long as it did.

I have been doing research and asking local mechanics what I should do about replacing this battery, most of them say to go with a lithium battery: it is lighter, can carry a higher charge, faster to charge, less susceptible to power drain, saves on gas, weights 45 lbs. less than stock, improves gas mileage, runs cooler, and lasts longer.

After I have the battery installed and drive for some time, I will update this review.

Update from Sep 2, 2021: Changed my mind, since Lithium batteries and the companies that manufacture them are so new, I am going to go with Toyota and their OEM stock battery since it comes with a 7-year unlimited mileage warranty.

Update from Sep 11, 2021: In my quest to find a new hybrid battery for my Prius, I have discovered several impediments; the first of which has to do with the type of battery that I want to use: OEM (nickel-metal hydride battery cells) or lithium-ion?

Secondly, cost. Third, warranty. Fourth, the company installing the battery and backing the warranty. 

Of course, I did my diligent research and on lithium-ion batteries, they were invented in 1970; then through years of further development, the first  car to use Lithium batteries was in 1996. So, that means lithium batteries have been used in cars for 25 years. That is impressive; but, I am not convinced. Companies are still improving on battery technology. Yes, lithium batteries charge and discharge faster than nickel-metal batteries, are lighter, take up less space and cost less. Wow! You'd think, after all those facts, I'd say yes, to lithium. But, I am going to say no. 

The reasons I have chosen to use the nickel-metal battery is: they are tried and true, have longer history,  have personally driven 185400 miles (ca. 298,372 km) on this battery, the reasonable price including labor, and I get an 8-year warranty with unlimited miles as opposed to the lithium 1-3 year warranty with 50k miles. Plus, it is a Toyota dealership, mechanic, warranty, and OEM part that I can trust and rely on for them to be there in my time of need, it gives me peace-of-mind. 

In addition, I don't know what is going to happen to any of those new battery companies in the future. I might have bought the lithium battery if they offered the same Toyota warranty, if I had known them for several years, if they had worked on my car, if they were local and easy to contact. But then what if they are a fly-by-night outfit and they either sell out to a large corporation or they close their doors and leave us consumers with no compensation. I think I made the right choice and can sleep at night.

Update from Sep 19, 2021: After having the battery replaced, I am pleased to say that the car performs better than it did before. The battery charge level remains around 80% most of the time, the mileage has improved by a few miles per hour, acceleration is much better, and when in EV mode the charge last longer and the car can travel further.

This Toyota Prius is the worst car I've ever owned!!! It has had electrical problems from the beginning.

I bought this car because my parents have owned Toyota's that have lasted much longer.

I can confirm this is the worst year Prius and I think there should be a class action Lawsuit!

I have had to endure $200.00 Light bulb changes to the Car not Starting at random times,to the EMP

System shutting down, Braking is a joke , replace the right Strut, Tires replaced three times, and now a dead Hybrid Battery at 130k miles. This is LOW for A Toyota.. the worst part is that Toyota is not taking responsibility for their crappy batteries and the fact that the 2010 is the worst year yet!