We love our 2007 Prius. Original battery and 293k miles. Still seems to be going strong and getting 49mpg. I used tech stream and looked at the voltage of the cells and they were all very close. ICE seems fine, although it does go through a bit of oil. I recently changed the trans fluid. I've not noticed any signs of battery failure, except possibly this: On a long trip a few days ago, with 4 occupants, I think I noticed the ICE revving pretty high as I was accelerating up to highway speed. It almost felt like a slipping clutch on a manual transmission. I think this symptom went away as I drove. Yesterday driving the car seemed perfect. I also was watching the info display and it seemed like possibly the ICE came on more readily than it used to- but this may have been me looking for a problem. I would think that my mpg would drop as the battery starts to crap out, but it remains >49 mpg, like when we bought it. I bought this car with 200k on it and figured on an after market battery pack, when the original finally failed. I wonder if it makes sense to wait for it to fail (and go for a world record), or just preemptively replace it, so that it doesn't fail at an inconvenient time?
start searching rebuilt batteries, company reputations and pricing, while you have the luxury of time.
You're showing a lot of wisdom by researching this ahead of time. If you're decent at DIY (and it sounds like you could be since you're already doing techstream), now would be a good time for you to keep an eye out to purchase a battery from a wrecked gen 3. Craigslist, ebay, etc. They're out there and sometimes you can get very lucky and find a low mileage 2015 battery in the 500-1000 range. The exterior housing of the battery is different, but the internal modules are interchangeable with the gen 2. I've built several Gen 2 batteries using Gen 3 internals. It works extremely well.
How about maintaining the battery: Prolong Battery Systems. Extending the life of your hybrid. – Hybrid Automotive I have it installed on our 2010. No signs of eminent failure, but doing it while the pack is still very healthy . Something to consider .
I think it does make sense to wait until it fails, as in most cases the battery continues to function for many more years longer than you might think once "you suspect it is about to die". I would certainly not pre-emptively replace with a rebuilt, because the chances are you will replace it with a POS pack that is likely way worse than what you had. The only pre-emptive thing that makes sense is a maintenance charging schedule using a grid charger, such as the HA Prolong charger/discharger system. When the inevitable happens, TMR-JWAP's suggestion also makes a lot of sense if you're a DIY kinda guy. Other than that, I wouldn't give it too much thought.
