Hybrid System Issues

Thank you for the log file. It appears that your scanner is not capable of reporting the P0A80 code, but you somehow reported that you got the code (P3019) for battery block #9 being bad. That is very interesting.

It appears to me that the problem is not the battery ECU, which you already replaced (I am assuming that the file was made after changing the battery ECU), or the wire frame #2 harness which is used for sensing the 14 battery block voltages. The problem is one of the two modules that make up block #9. All the battery blocks are in the 16.8 to 16.9 volt range except for block #9, which is in the 15.4 volt range. It's about 1.5V lower than the other battery blocks.

A Toyota battery module is made up of six 1.2v nominal cells connected in series. So, one of the cells in one of the modules that make up battery block #9 is bad. There are 28 modules (14 blocks) in the complete battery pack.

It is time to fix the hybrid battery. You can try replacing battery modules or replace the complete hybrid battery assembly with a used or new assembly, or maybe it is time to replace the car. You will need to decide what to do. How many miles on the car?

 

The original hybrid battery in your prius has lasted about 19 years. There is nothing better than a new Toyota OEM battery. If you want to replace it yourself, look online or call a few dealerships near you and ask the parts department for a price. I believe there is a good place in the Hoston area that uses a new OEM battery and will do the replacement much cheaper than a dealership. @rjparker can give you the name of that place.

 

Hometown Hybrids has a Houston, Austin and San Antonio shop. If you are in Gatesville, Tx their Austin shop would be closest or use their free mobile service.

$2495 new installed that will last 15 years
$1195 "rebuilt" with 2 year warranty

2004-2009 Toyota Prius New Battery

 

$2500 for an OEM battery installed is a fantastic price. Almost too fantastic. Their site says they are using Toyota OEM batteries (I checked, because some other businesses just say "New", and those are not OEM modules), so they must have worked out a significant bulk discount with Toyota. This must not make them very popular with the surrounding dealers' service departments, since those would likely be charging around $4000, and only warranty for 3 years instead of 5.

 

I used them years ago. They are legit and buy a lot of batteries from Toyota.

 

I would buy new even though its twice as much. Avoid the temptation to buy a rebuild even though some are available via shipment or occasionally from auto supplies. Some loosely use the term "new" or the counter guy does not know the difference. You pay 3/4 of new and have to still have it installed. The rebuild "guarantees" are not good or quick and simply remove the worse modules (out of 28) and replace them with better used parts.

 

Cylindrical cells do not have proven longevity. At best, you may get five years before problems return. Given that I wouldn't pay more than half the price of a new OEM. On the other hand, five years may be all you need, so, horses for courses.

 

Those new cylindrical cells normally last about 5 years. There is nothing better than a Toyota OEM hybrid battery. Why even consider something else when the original battery lasted about 19 years.