RTOD – how bad can it be?

My first chat post. Please be nice.

2007 Prius.

3/24/2024 96,385 miles: HV battery was replaced with a new Toyota battery
4/22/2025 125,840 miles: the RTOD with P3000, P3020, B1421
Battery Block 10 weak
7/7/2025 133,352 miles: the RTOD with P3000, P3020, B1421
7/10/2025 600 miles later: same DTCs again
7/10/2025 40 miles later: same DTCs again

OK, so I’m starting to pay attention. Block 10 voltage is 15.80. Next (lowest) is block 4 15.99. Highest block voltage is 16.16.

Is it the “red triangle of death”, or “doom”?

What should my next steps be?

Thanks and regards,

Jim x 3

 

Thanks for your reply.

I don't have any secrets here - what can I add?

I purchased the replacement from a Toyota dealership parts department. The part cost about $1950 with a $1300 core charge. I did the work myself. I'm not an auto mechanic but I had the requisite tools. I am a professional electrician - the system design was well understood and the swap was straightforward with no surprises. I picked up the new battery in its sarcophagus on a Friday and did the swap over a weekend. The sarcophagus on the pallet does fit in the hatchback with the rear seats down.

The car previously belonged to my parents and it did not do well since they were old and did not exercise it regularly. My impression is that a 2 or 3 months interval between uses is death for this car. They are now gone. Conversely, my daily commute is about 75 miles 1-way. Almost all of that is freeway miles at high speed, 55-85 mph with frequent accelerations and decelerations for traffic. Cruise control is never possible. My mileage has been consistent and good - about 43 mpg.

Since there was a simple 1 year warranty, I didn't think it fair to ask Toyota for any consideration.

What else do you need to know?

regards,
Jim x 3