How long will a Prime battery last and how much is a replacement?

We have two Priuses [Prii ?]

Our oldest has a bit over 200k miles on it. The dealership service manager has told me that have been seeing many Priuses with over 300k miles on them, without any battery issues.

I don't like it that the Prius has no error codes in it to check the 'health' of the battery. Either it works or it does not.

 

As with the older Prius Plug-in model, the HV battery typically wouldn’t be replaced as a unit because of wear; instead, one or more of the five HV supply stack sub-assemblies (part numbers G9508-47230, G9509-47030, G950A-47030, G950B-47030, and G950C-47030) would be replaced. These are shown as “No Longer Available” on parts.toyota.com, but I doubt that’s correct, though dealers may have to make special arrangements to get them. Other sources give the list price as $3,336.51 each.

I have no idea whether that price might change as demand for non-warranty replacements increases. The list price for the same parts in Japan is ¥91,500 each, which suggests that Toyota may have some pricing flexibility, even after U.S. tariffs, transportation costs, and dealer markup are added.

The Repair Manual (more info) describes many battery-related diagnostic trouble codes (DTCs), but I take your point: I don’t know of a convenient way to estimate the remaining life of the HV battery, until it’s reached a failure threshold that causes the car’s computers to store a DTC.

 

Toyota states that it will last the life of the vehicle on the Prius Prime website: "The battery in Prius Prime is designed to last for the life of the vehicle."

I've concluded that IF I keep it long enough for the battery to fail, and it isn't covered under any warranty, then I'll have a regular Prius from then on.

 

If your traction battery actually fails (RED Triangle of Death) then you won't even have a regular Prius, it won't get to READY mode. Also, the warranty covers battery failure, not simple degradation over time. Degradation will be indicated by loss of EV miles on a "full" charge, i.e., the battery will lose its charge more rapidly than you've been used to and you won't be able to drive as far on battery alone.

 

I'm seeing them on Ebay for $1000!

I'm also seeing lightly crashed but "totaled" Primes with under 20K selling for under $4K!!!
IMO two main reasons for this:
a) Prime is going to be near 100% reliable for first 10yrs, so no market for used parts.
b) Prime has CARBON FIBER rear hatch, and is "semi-Monique unibody" which means even a mild crash that leaves it perfectly able to drive around like before, is still not going to be able to be repaired to "good as new" as required in an Insurance Company/Legit Body Shop situation.

IMO, this also makes Primes fairly safe from being stolen. Why try to defeat fancy factory security for your chop shop if you can legit buy nearly perfect Primes for cheap?

 

Oh man, I didn't think about not being to start it. That would be my main area of concern then. Anyone who buys an EV though hopefully knows that the batteries will degrade in EVs over time. Have to keep that 20% or so going!

 

Most hybrid and EV batteries are warranted for 8-10 years. Prius nickel hydride batteries are known to be practically problem free for that amount of time as well. Prius lithium ion batteries have not yet been around long enough to know for sure. I’d say if you’re the ultra cautious type, trade in the Prime after 10 years. Otherwise, jump through that hoop when and if you come to it. Past the warrantee period, there are a lot of different factors that can affect battery longevity: ambient temperature, charge speed, discharge speed, length of time at extreme charge states (full or empty), as well as small differences in the individual cells. The battery may fail on year 11 or 22 or 33 or anywhere in between, with greater likelihood the older it is and the more the small factors add up.