P3000 and block-failure, but cells test to good voltages?

Hello,

I'm new to the forum, but I've been a lurker for a while and have used the resources for many a fault fix!

I have a 2005 Prius, about 320K miles (some toyota '05s odometers only display up to 299999)
I recently had all the warning lights, OBD checked and got the P0A80, P3000 and P3014 (block 4) codes-- confirmed block 4 would drop very low with the live data. Not my first time, so I took the traction battery out low and behold, one of the block 4 cells was reading very low voltage (6.6v). All other cells were at 7.9v-8.0v. So I swapped out the bad cell, (and its pair because I borked the torque reinstalling it. whoops!). Get it all back in, no codes and it runs great for about 30 minutes. then it starts firing P3000 and P3021 (block 11) codes (it does NOT display P0a80). I can clear them, and it runs fine for a few minutes before coming back.

My OBD reader shows block 11 a little lower than others, but still in a good range. it does sometimes drop to a low voltage for a point before going back to normal. It is more erratic than other blocks. I replaced the bus-bars with the nickel-plated ones and new screws the last time I replaced cells.

Before I take it back out for frustration, is it possible that two cells testing at a good voltage (7.9-8.0v) suddenly drop off to cause a fault code? is it more likely that I messed up something re-installing? (Not my first time doing this, so I'm pretty cautious but can still be scattered). Is it possible to cells have faults that won't check out with a voltage meter?
Could it be something else causing the fault?

I had a refurbished replacement originally, and it was garbage. they did two warranty replacements in a year, and since then I've just been replacing cells when they go. Lil Sparky is great, but I know I'll be needing to move on sooner rather than later, so the cheaper replacements is the way to go for me right now.

Thanks! I wasn't able to get Dr. Prius working with my OBD II reader, but I'll look into a better reader if that can help this and future diagnosis.

 

after much shipping delay, I was able to get an OBDII scanner that worked with Dr. Prius.

First up: I did start to finally see the P0A80 code. Additionally, unlike my other failures, the car would go into Limp mode after a few minutes of the code. It is still variable. sometimes I've driven it for 20-30 minutes without codes, sometimes they are immediate.

With Dr. Prius, the full battery test showed some issues with block 11 under upper voltage load -- I could never get the the bottom voltage to trigger (turns out I'm a giant baby when it comes to slamming on the brakes). Sometimes it would complain about blocks 1 and 2 in "internal resistance", but that would also come and go.
Watching the graph, voltage differences were pretty stark, often over 1v when under load. The voltages also seemed to jump around a lot.
Block 11 was the worst by far, but the others weren't looking great by the eye and the size of the bars.

And finally, the "life expectancy" test, I had some troubles figuring out what to do, but it gave my battery pack a whopping 1.6% of life remaining.

So I love having data, and though I've had some troubles recording and exporting, I'm glad Dr. prius shows these data as graphs. As expected, a lot of my battery blocks are in poor condition, and block 11 seems to have the most issues.
I guess my main question is: are the bad readings possible the cause of something beyond the battery cells, or even the battery pack?
e.g. could the battery ECU cause bad readings of voltages, and/or could something like the generator be failing and causing similar issues?
I'd like to get Sparky pack up and going, even if it means a new set of cells, or possible a whole repaired battery pack, but I don't want to spend the time and money doing that only to find out the problem is somewhere else.

Thanks!

 

SoooOOooooo.... FUNNY STORY.

Always check the calibration on your torque wrenches friends! And... maybe always check that you actually torqued everything properly.

I started to take the battery out and see if there was any corrosion or anything, and low and behold on block 11 one of the bus-bar bolts was surprisingly easy to unscrew... I got my torque wrench re-calibrated, then re tightened, re assembled everything and no more throwing codes! I think I got a little gun-shy after the threaded part of a battery cell got over-torqued without my wrench clicking. maybe i was too cautious.
I went back through Dr. Prius testing, it flags block 2 as a potential future problem, but otherwise everything is back to less than 0.3 volt differential. it passed load tests positive and negative, and 'battery life' is now at about 60%. So Sparky is back to drive-able. I'm sure I'll get more P030XX codes before too long, given I've replaced 11 cells (from a crap refurb) without doing any intentional re-balancing-- but given other issues unrelated to the battery (a sealed-but-problematic windshield crack, likely AC leak, no cruise control, and needing schedule maintenance twice the value of the car, etc), eeking out a few more months is a win all around!

Only other problem is that the battery temperatures get high; about 120F. I do live in a high-desert that also has plentiful car-crime. Daytime temps are well into the high 90s; I can leave the windows open at work, but weekend outings are gonna be warm. Learning how to keep the battery fan on high is the next step. Thanks again everyone! This is a great resource and a great group of people to help with problem solving <3