2008 Prius w/ failure codes P3000 and P3012

Hello Prius Pals,

I bought a 2008 Prius about a year ago used. It worked really well and had good mpg since I bought it. The 12v started acting up (died and low brightness lights) once I accidentally left the lights on one night. That resulted in me finding the all too common rusted and corroded 12v battery area because of leakage. Sealed it up with some silicone, drained the 12v reservoir, replaced the 12v, and the problems went away.

I moved to a new location and one of the tires unfortunately went flat. I didn't have the funds to replace the tire so it kind of just sat for several weeks.

The 12v was dead so I had it recharged and the car was alive. However, nearly all the dash warning lights were on included the big red triangle and the red exclamation mark with the car on the heads up display. I noticed the big HV battery was almost entirely discharged so I drove it around a bit but it was extraordinarily slow (failsafe mode?). I used a bluetooth OBD2 reader and the Dr. Prius app to get some readings and saw that there were two error codes P3000 and P3012. The dr prius app also showed that the first two cells were very low relative to the rest of the battery cells.

I saw a video online saying that this can happen if the car sits for long periods of time and clearing the codes and driving it around to charge the big battery back up might help. So I cleared the error codes and drove it around for ~20 minutes only for the car to jolt a bit and have all the error codes and display warning lights come back. The error codes were the same (P3000 and P3012).

Another symptom I'm getting is the fan in the back comes out LOUDLY once the car enters (what I think is) failsafe mode.

I'm not sure what to do. I cannot afford a new HV battery and am very much not comfortable driving it around at the moment so bringing it to a specialist or even the dealership doesn't seem in the realm of possibility for me.

Anyone have any advice or experience with these error codes? Any help would be appreciated, thanks!

 

Posting an update with some additional logging data from the Dr Prius app. I started the car up after it being off for a few days. No error codes since I cleared them last time. It started off at ~30 percent charge. At this point the engine turned on and charged it until it was at 100% charged state. Then I pushed my foot on the gas pedal to drain the battery. The battery drained until ~40 percent and then the engine came on to charge the battery. At this point the whole slew of dash lights came on once again and I had the same error codes.

Luckily I was recording with the Dr Prius app and have a nice little csv that caught the event. Nothing sticks out to me as indicating something "special" happening but I'm attaching it just in case someone can interpret it better than I.

The one thing that does seem strange to me is the Amp reading which seems to fluctuate quite a bit from ~1 to ~5 (volts?). Then at some point (when battery nears ~42% SOC) the amps go into the negatives and then come back up to positive but stay around ~0.08. This also coincides with the Charge Limit going from 22 HP to 0 hp and staying there.

So from what I'm seeing, something (evidently bad) happens when the battery reaches near ~40% SOC and the engine kicks on and tries to charge it.

Do I just need new first and second modules? Or is this something more?

Again, thank you for anyone who is willing to look into this or offer advice. I'm not sure how much a battery module replacement would cost but I can't afford a whole new HV battery or other potentially costly replacements.

 

The HV battery is still the original. I'm nearest to Portland.

 

So you'd say Green Bean Battery wasn't very good in your experience? They're the closest hv battery people to me (at least so far in my search). So it's a little disheartening to know even the best option for replacing the hv is not so reliable haha.