Hybrid Cells Reading High in Voltage??

This is the 3rd or 4th time that i've had a battery issue. I'm pretty sure it is the 4th time. My wife's 2006 Prius just rolled over 200k miles. She was leaving work and called me that her dash lights came on like they have in the past, but it was still driving fine, so i suggested it was fine to continue home. Instantly, i ordered a battery from ebay around 5pm. The same guy that i've bought from before ships out of Florida $36 OTD and it arrived Monday afternoon!\

Anyway, after working 12hrs on Monday, that evening I took the hybrid battery pack out and started testing each cell. Oddly, they ALL tested above 8V; most around 8.24 & 8.36. Which is weird, because i know that when i've tested them before, most were high 7's and only a few were about 8... The lowest one on this most recent test was at 8.11. Even though my gut said it was the 5th cell in from the ECU(ECM same thing?) that read 8.11, i put the pack back together and put it back into the car and hooked it back up. Why? Because i assumed it would be as easy as the other fixes.... haha I totally forgot to scan the fricken car!!! ugh!!!

The codes came back on again the next day, so this time i scanned it. I'm still getting used to the new version of techstream that i upgraded to (Ver 12.00.127). The previous version would scan the whole thing. This version it looks like i need to select modules to scan. So i selected the Hybrid HV option and it showed code P3000-123. Then i clicked on the snowflake and it showed/confirmed that the 5th cell is most likely the issue. "Battery Block Vol -V11 15.11". All of the other blocks are around 16.4* volts...

So i took out the bad cell, which took a bit to undo all of the side and bottom bolts/nuts, slide the cells toward me and put in the "new" cell, which reads at 7.84V. The old one still read at 8.04V, but i'm assuming the integrity of the battery is dying? So i put it all back together and on the very LAST cell, i tighten it too hard and effing break off the stud on the first cell............ UGH!!!!! Whatever, it is late and i'm tired, and it looks like there is enough of the stud left for the metal to tough and get a good connection with (wishful thinking).... So i put the battery back in, pull out of my neighbors heated garage so he can go to sleep (Michigan is cold...) and i drove it to work this morning.

I got almost to work before the dash lights came on again. So i scan it again in my work parking lot. This time, i took my time and scanned multiple modules. I still get "P3000-123 Battery Control System", then in another module i get "P0AFA - Hybrid Battery System Voltage Low". And under the "ABS/VSC"TRAC Live" tab, codes: C11249, C1259, C1310, C1311 & C1313. I'm pretty sure C1249, C1311, C1313 show why one of the brake lights keeps going out due to an Open Circuit. And C1259 & C1310 will go away after the bad cell is fixed. Still weird, the last version of techstream gave me a specific code for which cell pack was bad... So i look at the snowflake for P0AFA and it shows "Battery Block Vol -V01 -8.86". Yeah, negative might be a bad thing.... But that is the one that i broke off... The rest all show in the low to mid 15.** range. Except the one i replaced last night, 14.63V. I assume that is because it hasn't gotten a chance to charge up yet?

BUT, something that just dawned on me, maybe none of the cells were bad??? After reading some other postings this morning, it dawned on me, the hybrid cell pack fan wasn't blowing 100mph like it normally does... Plus, maybe that is why the scan didn't show a specific battery pack code like before. Which i doubt, because cell pack 1 is clearly effed after i broke the stud off... Any suggestions? Maybe after i fix the cell with the broken stud, it will work again? Do i need to strain the batteries more before testing? Maybe not a cell since the fan wasn't blowing like crazy?

My wife is due with our first child (daughter) on March 4th. I'm really trying to have this fixed and not spend a lot of money on it, before the baby is born... Please let me know if i need to include additional data, or if uploading pictures of the results will help at all. I have the scanner/laptop in the car and can run out quick to do another scan.

 

What do you mean by load testing? I've tested it while fully turned on (driveable) and with the power button pushed twice without pushing down the brake.

Usually, i just scan the car, it tells me which cell is bad, i double check it with my tester, swap out the battery with a replacement, and i'm good for another 6 months...

 

Thanks! i started reading up on it after your post. I drove the car, but i think it seemed to charge the batteries still. So i put the car in reverse and it seemed to use battery mode, but i don't think i did it long enough to wear down the battery charge...
That seems simple enough with a light bulb.

I did order another battery this morning though. The attached file shows a screenshot of the last scan i did. I think/hope/wish that after fixing the battery that i broke the stud off, it'll work again. For another 6 months, until another cell goes bad again... It is at 200k miles...

Oddly, i keep seeing posts that say the cells closes to the ECM are group 1 and the two cells furthest away are group 14. But the very end cell that i broke shows on my techstream scan as block 1... And the one that i just replaced was number 5 in from the ECM, which as improved block 12. hmmmm...

 

Thank you all for your input! I had not clue about the load testing! After the replacement battery came in the mail to fix the one that i broke the stud off of, everything seems to be working, with no dash lights on. I got lucky replacing the one that i originally thought was bad. The voltage was only slightly lower than the rest of the cells, so i assumed that was it. But that could definitely become a guessing game if i don't do the load test, i'm seeing. Thanks again!!!

I've been ordering used batteries from the same seller on ebay for $36-$39. The ones that i just bought came out of a 2013 Prius. My wife's 2006 Prius has 201k miles. If it was still around 100k, i'd replace the whole battery pack. But we'll probably drive this car until it dies. Well, until student loans are paid off and we have the cash saved up for another car.

Right now, i'm around every 6-9 months that another cells is going bad. If it starts happening more quickly, then i might rethink my ways... haha But a 4-6 hour job every six months isn't so bad. Valvoline High Mileage Synthetic Oil. I do need to replace the spark plugs and change the transmission fluid soon. But this car has been very cheap to maint..... I'm not going to finish that sentence..... hahaha