Battery Dead problems of the 2001 Toyota Prius

Hv battery failure, prior to failure of hv battery vehicle exhibited error codes indicating that at least two battery modules had a greater than 1. 2 volts between max module voltage and min module voltage (hv battery consist of 38 battery modules 7. 2 volts each). However, vehicle still operated although in a fail safe mode (no cruise control in fail safe mode, etc). Upon attempting to start vehicle heard loud explosive pop sound and vehicle would then not start. After removal and disassembly the hv battery pack I discovered tha two battery modules, out of the total of 38, had a circular burn between their ajoining plastic cases and the top of one of the two modules had exploded open -- exposing the battery plates inside (both burned cells no longer measured 7. 2 volts, but about 0. 32 volts). Burnt smoke residue showed on top of the hv battery pack inside metal housing as well as on the one battery module that had an exploded top. I replaced the hv battery pack no further error codes have been noted since replacement. Damaged modules showed evidence of an explosive force occurring and burning or shorting between battery modules.

Auxiliary battery on Toyota Prius 2001 and Toyota Prius 2004 fail if the car is not driven at least every 7-10 days. This prevents the car from starting. We purchased a 2001 Prius used March 2004, and a new 2004 Prius in June 2004. The auxiliary battery failed on the 2001 Prius twice, and we replaced it once. Recently the dealer service rep told us that it is a known problem that the battery will not hold a charge unless driven every 7-10 days, and should be "disconnected" if parked for "prolonged time. " this is potential safety problem for car not starting, such as if returning on plane after 2-3 week vacation and not being able to start the car, risk for vulnerability awaiting jump start. Toyota's only response is "well, it's a hybrid. " they say the "hundreds of computers in the car drain the battery when parked. " they could have designed in some automatic or simple switch to address this. They also could notify the potential customer of this design flaw. They did not inform us, or any of the other Prius owners we have recently discussed the issue with. The owner's manual for 2001 model makes no mention of it. In the 2004 manual, there is a brief mention of need to disconnect the battery if parked for "prolonged time" but does not define that. Although we have been happy with other features of the Prius and other toyot as we owned in the past, we consider this to be a serious and risky design flaw. Furthermore, we consider Toyota's sales people and sales brochures failure to notify us of this problem to be a significant breach of goodwill and respect for customer safety and satisfaction.

On June 6, 2006 I took our 2001 Toyota Prius to a local Toyota dealer because it had been losing power while driving. The Prius mechanic told me that it was "normal" and that there was "nothing wrong. " I responded that I knew that something was wrong with the vehicle. On June 15, 2006 on the way into work, the car completely lost power while driving on the interstate. Fortunately, we were able to pull over at a relatively safe spot. Had it stalled in heavier traffic or in a different lane, we could have died there. The screen showed "main battery failure," and the car wouldn't move. I had it towed to the dealer. The technician tested it and the only code shown was an "accelerator assembly pedal. " neither I nor the technician felt that this was the problem; the technician felt that the problem is in the inverter--the part that cycles power back and forth between gas and electric. However, Toyota regional refused to replace the inverter, saying "we are not just going to throw parts at the problem trying to solve it. " I was told by the dealer that I would have to replace the accelerator assembly pedal at my expense, even though that will likely not resolve the problem, because Toyota "will not do anything else unless you do. " this type of powering down and stopping is a known issue with Toyota Prius cars, more so with 2004-05 (for which an NHTSA investigation has been opened), but also with 2001-03. There were fewer of the 2001-03 cars on the road, so the number of reported instances is less, but the internet contains many complaints from Toyota Prius owners regarding this issue. This is a very serious safety issue. As Prius cars age, this safety defect will become increasing apparent and hazardous.

After sitting for as many as 2 days without driving, there is a battery failure. This has occurred on numerous occasions (8-10 times), and the dealer has sent a tow truck out to either start the car or tow the car into the dealership. At one point, the car was in the dealership for 3 weeks while they worked on solving the problem. They have put in several new batteries, but the problem continues. The latest occasion was this past week (October, 2002). I was without the car for 3 days. No problems were found at the dealership except for battery failure. In the past the dealership has provided me with a battery charger, but the battery charger is currently not working properly. Dt.