Don't know if anyone else has read this yet but Toyota might have made a drastic change in the way modules are connected in the HV battery pack in the Gen 4. Not sure if this is for both the NimH and Lithium battery chemistries. Here's what was in this article A look inside the new Prius hybrid system posted on autoblog two days ago: Electrical losses were also reduced: "Instead of joints put together with screws on bus bars and connection bars, we now weld them together," If this sentence is about the battery pack, I don't like that at all! It might not be possible to swap modules in Gen 4 packs when the time comes to replace a failed module or two.
This might also help the reliability. It's a tradeoff, I suppose. I'm just glad they guarantee the battery for as long as they do. That won't always be the case, I'm sure.
I think some of the failures was because of corrosion. I know there are a number of youtube videos of people taking apart the connections, soaking them, and putting them back together again for a cheap $10 fix to the dreaded hybrid battery failure issue in the past.
Maybe "welded" is a poor translation, "soldered" would be more to the point?? (Maybe, just speculating.) Still, it will make any DIY efforts trickier.
