2006 Prius 140k miles: Rebuilt battery replaced 4 times in 1 year - decision to keep or trade?

Yes. I agree it may not be the engine power in this case. However, the original symptom did include low engine power and the error codes matched mine. So, I lean heavily to looking at why engine power seems low. Valve clearance? Sticky guides? How is oil consumption? Etc. it could be electronics as well but again I go back to engine power. If the engine does not have enough power to keep running on its own, it will call on the hybrid battery for Support. And if the battery does not have enough time and charge to recover then it will drain and give the triangle of death as my car did. A good test is to drive up a long steep hill and watch if the battery drains down toward purple.
As I stated, I am still using the original hybrid battery after 225k miles. It was the cat for me.

 

I would not trust a company that cant spell their name right..* for, not the number four*

 

No, they had it right. He was on battery four.
Maybe they just need 4 tries to get it right and try to let you know ahead of time?

 

I had a long list of codes, cat error was in there but I did not believe it. So I checked everything else. Again, the test that convinced me was to loosen the connection before the cat to let the pressure escape and bypass the cat. A short drive on hills proved the problem went away and the battery charged. If allowed by your state you can purchase an after market cat for about $280 while the oem Toyota version can be as high as $1200 or more. The nice thing is you can test first to see if the cat is the issue before spending the time and money.

 

Did you go with an OEM or aftermarket cat?
If aftermarket, which one did you end up buying?