HELP!: HV Battery modules splitting charge?

Hello y'all, after several months and many ups and downs with my 06 Prius I think it's about time I asked for help.

After my original HV battery have or just in time for the holidays (and the birth of my second son) last year, I bought a refurbished gen II HV battery from a guy on Facebook marketplace to save some money (it was my only affordable option). The problem is that the new battery is showing strange readings on blocks #2 and #3. (see attached photos)



When I dismantled the hv battery and tested (not under a load) each module seems to be healthy and I do belie this was a recently refurbished battery with a good bench test as the seller on Facebook claimed.

I noticed that the two blocks are next to each other and that one seems to be compensating for the other and wondered if this may not be a battery issue but rather a sensor problem related to bad connections.

Do these pictures or this information suggest anything specific to you, the geniuses of PriusChat? Did I just spend big money for a hv battery with two bad blocks or do I have a chance to fix this problem inexpensively so I can get my car back on the road?

I'm available to fill in anything I may have left out or answer any questions. I'll also let you all know how this turns out.

Thanks for any and all help!

 

Thanks guys for that tip, I’m in the process currently of swapping the busbars with the cleaned busbars from my old hv battery, which I had cleaned just before a module exploded on me... (long story). I’ll check the sensor wires at both ends and get back to y’all with my progress. I really appreciate the help.

 

Hey guys, quick update: you were spot on! After a week of being too busy to get any work done with it, tonight I was able to check out that connector and, as you can see from the photo, it's burnt and blackened.



So here is my plan moving forward: I have the old hv battery casing and ECU that (to my knowledge) is in peak condition and I have this refurbished hv battery with burnt and some frayed wiring. So I'm going to remove the braced modules from the refurbished battery and place them instead of the old casing.

Does this plan bring up any concerns?

Also when I'm done with this I will have almost a complete hv battery worth of pieces that I would love to convert to cash or at least dispose of appropriately. Any tips or advice towards those ends?

Thanks again!

 

BAD NEWS.

As I was trying to take off the bolts fr the refurbished battery to swap the casings and ECUs, I came across a nut that had been severely over tightened and in try the loosen it the whole stud came out.

I'm feeling like all this work and effort is for nothing since I'm now probably going to have to take my best module from my old battery to replace this now studless, perfectly good module.

Unless...

Is there anyway to replace or refasten the stud in the module's plastic casing? The stud didn't snap or break, it feels like it just came out. Does anyone know how the stud is set in the module? Please advise.

If that module is screwed without that stud, how can I pick the best cell from my old battery to replace the studless one? Am I most concerned with voltage, amperage, or capacity. I have dr. prius readings for bother hv batteries if that helps:

Old battery reading:


Refurbished battery reading:

Any and all help is appreciated.

Thanks.

 

Thanks Eric, I will upload a picture of the damaged module as soon as I can grab a picture of it later on today. I will also grab some photos of my exploded module from the old battery and anything I think of. Anyone is welcome to use these pictures if they can help inform others. Thank you for all the advice. I had quite an adventure last night so I have a larger update incoming shortly.

 

UPDATE: MURPHYS LAW IN FULL FORCE

Yesterday, I spent a full 9 hours on the Prius even though I expected to only have 2 hours of work to swap out the broken, studless module from the refurbished hv battery, replace the busbars with ones that we cleaned to a near new appearance, get the battery back in the car, & get the readings to examine my work.

But things got complicated once again.

Yesterday was or first snowstorm of the year with cold temps & a ton of snow making it difficult to work on my car since it is outside.

Regardless, we moved & fastened the hv battery into place and connected it to the car, but before connecting the ground to the 12v battery, I thought to check the voltage. It was barely carrying a single volt of charge. I went to remove it so I could turn it in for the core charge when buying a new one BUT the battery was frozen in place and would not budge. The exhaust vent next to the 12v battery must have allowed water into the well behind the wheel & it was frozen solid.

First, we started chiseling away at the ice but that was getting us nowhere but out of time. Next we tried a heatgun, carefully avoiding overheating the battery itself while melting the ice, & sopping up the water with paper towels. We were having trouble with the cold fighting our work so we poured some antifreeze into the well which helped stop the water from refreezing but did not help melt the ice as we had hoped. After doing this for a couple hours we finally came upon the winning strategy: we boiled water in a kettle, poured it carefully into the well & removed the water with a shopvac I borrowed from a neighbor. We should have started with this method because it work fantastically well & I was able to pull the battery free from the car.

Next problem: finding a replacement.

After a few phone calls I found a couple place that said the had the replacement battery I needed. So I embarked on the perilous winter roads to pick one up. This was slow going. Once I got to O'Reilly's Auto Parts the battery they had has a different, larger opening for the battery's vent tube. So I passed & went to Advanced Auto Parts & found the same problem. I called or stopped by about 4 other businesses & they didn't even have this battery type. I checked on Amazon & one person was selling an exact match but for nearly $500!

So I went back to O'Reilly's, checked their return policy, & bought the battery. Got home to try it &, sure enough, the elbow at the end of the vent tube is too small to stay in place in the new battery.

I called it a night, defeated.

Any advice? I can return the 12v battery or I thought maybe I could find a replacement elbow piece for the vent tube but searching online I couldn't find any clarity on what to buy. The new battery has a larger hole and a notch cutting into it on a diagonal.

Any help would be appreciated. I'm close here but this has been a really painful experience over the last 4 months. That & I just miss my Prius.

I do have my old 12v battery still & I charged it overnight. If the readings on it are good enough, I may try to use it just to start the car once to test the hv battery's health before I completely fasten & brace it into place.

I'm also curious on how I can keep water from getting back into the area in future. I have also sometimes found the floor of the backseat wet for some reason. Any tips on that front also?

Thanks again. I have learned so much with all of your help.

 

UPDATE: COULD THIS BE THE END?!

Hey y'all, the car is back together. I used a thicker tubing as a adaptor for the larger sized venting hole in the 12v battery. Started the car with no trouble. Everything looks good except the module in block #4 that I had to grab from the old battery is definitely reading lower than all the others. (I have pictures on a different phone that I owe you. I'll have then up soon.)

Car drove great but the winter roads meant that I couldn't really lean into it as a test. I'll be doing so this morning as I have to accelerate onto an interstate to get the work. Fingers crossed.

I put everything back together and I'm back on the road. Lord willing this will last a good while but regardless, I learned A LOT from this experience.

I should have pictures of the studless module and some current obd2 readings up soon. And if anything bad happens... Y'all be the first to know....

Thank you again to everyone for your tremendous support and timely advice. Hope you all have a great 2019! God bless!