Sorry if this has been beaten, but I still don't understand... If the HV battery dies, is the car still drivable? Is it safe to continue driving? For how long (distance)? I just had my battery deep cycled, so I'm not worried; this is more of an academic/what if exercise.
no. the hv battery starts the engine. no juice, no gas. seeing that the prius engine shuts down, a lot, you're really up a creek. but not to worry, it is extremely rare.
As "Bisco" say's if the hybrid battery (HV) fails completely (no output voltage) the engine will not start. This is because the HV battery is used to start the engine. Usually however the failure mode is low voltage in one section of the battery causing a fault code to be issued, but the car will continue top operate, and start using engine power only. John (Britprius)
Thanks everyone! I read about people hobbling home after dash lights up like an Xmas tree. And I know the 12v is involved, but I wasnt sure if it was possible to have the HV battery die AND still be able to drive. Makes sense now. We took a 150 mile drive today and the blue egg did fabulously with its newly deep cycled battery. In a couple of months I'll get it assessed and see how it's doing.
In the context of your question, the 12V battery is not involved. The HV battery only is used to start the engine, not the 12V battery. Limp mode will occur with a perfectly good 12V battery. A failed 12V battery causes the various ECU's to fail to boot at start up.
I got the triangle of death icon, read the code at Auto Zone, and sure enough a few cells had failed. I called Autobeyours in Scottsburg, IN and set up an appointment. About a week later I drove the Prius over 220 miles to the shop and had it swapped with a refurbished one. The ride was rough the last 100 miles; it went into a safe mode, heater was weak, cooling fans were screaming and it maxed out around 45 mph but it got there no problem. After the swap (took about 1 hour to change it out), I drove back home at ~70 mph. It was swapped at 192k miles, now I'm at 206k. I highly recommend Steve at Autobeyours if you have a similar issue and it is within driving distance.
Steve at Autobeyours said the majority of the HV failures he sees happen around 150k, and that if your original HV lives past 200k, then usually it will continue to work fine. I think it cost me about 950 out the door; it seems like a lot but its only ~3 months of car payments if I had just given up on it.
Mine started showing signs of failure at 120k, so I had it assessed and rejuiced. About $700 for me and if it goes another 100k, I'm a happy camper.
Longest I've seen on an original Gen2 battery is 320k miles. Many fail between 150k and 200k, a few sooner. "Refurbishing" a pack will typically give you 1-24 months more life. No way will it go another 10 years or 100k miles.
