How long can dying battery go on?

I can tell you that when it starts throwing codes, regarding battery imbalance, and low voltages on modules, you'll be pulling to the side of the roadway quite often. You'll have to put it in park, and restart the car, to go again. Did this on a 700+ round trip, and it was quite a pain. Upside, I never had time to get tired, and fall asleep at the wheel.

But, here's the kicker (SO FAR). The pack had two dead (0.0vdc) modules when it was purchased. Replaced those with some I thought were good, they couldn't recharge/hold above 7.2vdc, so we attempted to rehydrate, helped, but not good enough, still generated error codes. Then we replaced those modules with some we verified would hold resting voltage at above 7.2vdc, and so far, the car is working very nicely, both power and charge seem to be normal.

Hopefully, you could replace some modules, and get a few more miles out of your original pack, if you desire to go to the trouble and fun of working on the HV Pack yourself.

 

1) be sure it is not the 12v battery failing, a lot of those symtoms would occur if the 12v battery had a dead short in one cell.

2) Better than new: 01-03 Toyota Prius Upgraded HV Hybrid Battery Pack: eBay Motors (item 130410475773 end time Jul-24-10 21:23:44 PDT)

Gen II cells in a Gen I case

 

Our pack buss bars were seriously corroded. Cleaned w/wire brush and coated with a protectant to keep that from happening again so easily. You do however need to make sure your low voltage battery is good. Most parts stores will load test it for free, and while there have them test for the codes while there are still errors in memory.