i got 2010 prius with 118 k. other than routine maintenance, the only thing i replaced last year was a rear bearing ($400) i was planning to replace the 12v battery sometime this summer, waiting for the battery warning light to come on. it never did. half of the display on the right side did not lit up. i was not able to put it in drive mode. after turning of and on a few times, i was lucky enough to put it in drive and went home. radio, speedometer, headlight were still working. after i went home, i checked the battery voltage. it was 12.3. next, i recharged the battery for 6 hrs. next morning, the whole display work and i was able to put it in drive and get to work. after work, on my way home, i was able to put it in drive after turning the car on and off 4 times. half of the display didnt work. on my way home, i picked up a battery from dealer ($191). i replaced the battery once i got home. now everything is fine. it has been couple days already without any problem next stuff to do are the coollant in both the ice and the inverter
there is no such a light, LOL. a few of us argued there should be one. on the other hand, toyota wanted to make sure driving prius mimics driving a regular car.
I'd say you ignored the warning. Do you really want to be stranded (it WILL happen when you don't have time for it). You DO need a new 12V battery. They can be had from other sources than the dealer.
