Our 2006 Prius went to the dogs

When our high voltage 160K+ HV battery died last spring, it took the 12V battery with it. That's what we were told by our Toyota dealer after a week in the shop (the factory trained techs did little the first 6 days but lose the original smart key. Finally got the diagnosis and jaw dropping estimate.

We had no intention of spending more than the car was worth on a new Toyota traction battery which would be warrantied only one year. Nor did we have anything in the way of shops or mobile techs within an 8 hour drive. We purchased a new 12V and installed it since we needed one anyway. Nope. The nightmarish dash display reappeared. Bought an OBDII TechStream Lite gizmo for cheap and read DTCs P3000, P0A80, C1310, B1411, B1433, AND B2795. The B2795 was courtesy of the dealer, who had programmed a new key. The P3000 and P0A80 were hybrid control and HV battery codes. The others related to the air conditioning system temperature sensors (the 'everything gets those' codes). We didn't pursue those since our AC worked fine and the dealer mentioned nothing along those lines. After finding no one to fix our car within our budget, we purchased another Gen II HV battery from a junkyard and put in in. Dashboard display cleared. Codes cleared except for the B2795 because we hadn't programmed the new key yet. There was an 'incidental' code B1421 which being another AC code, we decided the heck with that. (AC still worked fine.)
Car fixed!

So happy were we and the Pri until gasoline prices dropped and a shiny new Jeep caught our eye! Our Pri still carried the load, though. She was our 'go to' car for errands and the park.

Then winter came and with a 4WD with heated seats at hand, the little Prius sat neglected outside the garage.

Bottom line: I have been feeding off help, hints, and tidbits gleaned from PriusChat TechForum in a valiant, last ditch effort to save our girl. Once I felt confident in what I was doing, I pulled the original failed battery from the shed and opened it up to assess a rebalancing process for modules I would be taking from it to use to fix the one in the car. Guess what I found?

 

I considered the core + shipping when comparing our options. Just missed getting one from a local wreck from craigslist. The wrecker wanted $800 shipped and ebay coupon brought it to $760. Knowing I could keep the core factored in the decision because I figured it was either (a) a short term fix and I'd be learning to rebuild a hybrid soon, or (b) there would be no more battery issues before we decided to sell the car (in which case I'd resell the original junk core on craigslist to recoup a couple hundred).

 

I thought it looked bad and it surprises me fan was still working. What bothers me, however, is not the appearance of the fan. It is the appearance of the original core. Specifically, the hair between original modules (esp. where there is evidence of electrolyte weep) that looks as it was forced into gap(s) between some modules. Rather than provide extra cooling, the perforated module side plates may have been compromised with hair (an insulating material) thus further degrading an overheated module. I'm still shocked the dealer had the car a week (assume he found same ambient temperature differential codes I did) and never considered an obstruction of the HV forced air cooling a contributing factor (it would have been apparent we had dogs).

I hadn't the slightest clue or care about the Prius' engineering until late. I just knew she is a well designed vehicle ahead of her time and still in that regard the class of hybrids. We took her to dealer for regular maintenance, etc. Its not like we purposely junked our car. But we did put the furries in the back with the rear seat backs folded down! 160K miles took its toll, I think. As often as the dealer recommended the routine maintenance items like cabin filters, etc, which we changed religiously, he never mentioned the innocuous looking trim vent behind the rear passenger seat back. Even when she died.

 

It would have but we couldn't budget $4500 to repair a $3500 car. We did consider driving to Ohio to buy a new battery wholesale, but still it was $2200 and I wasn't confident (then) my ability to install. As it worked out, I don't regret the decision. A new battery would be subjected to the same compromised cooling system at which the dealer never looked.

 

I have the cooling fan cleaned. The individual battery modules from have been load tested (one lagger at a minimum will be replaced) and are being rebalanced. Question: how do I remove the rear passenger side air vent trim grill to install make shift low-restriction add-on filter? The trim opening is protected with a riveted cover that looks like something you'd slide behind a grill in a room air conditioner. Looks like it if nothing else it would benefit from a rinse in the sink. Is putting something else in there defeating the purpose?

 

thanks!