I have an 05 Prius with 172k miles. I am wondering what if all gen 2 batteries (04-09) will be compatible with my 05 Prius when I am ready to replace it. And possibly would a gen 3 battery work in my Prius? Reason I am asking is because I want to get a battery from a wrecked Prius and I want it to be as new as possible
All gen 2 modules are compatible. Even the battery cases are interchangeable. Although the Gen 3 and Gen 4 cases are different and will not swap into a Gen 2, the internal modules ARE interchangeable. Just be sure to do a complete 28 module swap. Pay particular attention to the polarity of the modules as they are installed in the original battery, and install the replacements to match. I've built many Gen 2 batteries using low mileage Gen 3 and some 2016 Gen 4 NiMH modules. If you get one from a Gen 4, just make sure it's the NiMH version and not the Li-ion version. The difference is obvious. There is no way the Li-ion modules could ever be mistaken for the NiMh modules and accidentally mixed up.
So I pretty much just swap all the gen3 or 4 modules into my battery pack and it should be good to go? No need to balance it or anything?
