My daughter is using the Prius this semester. Apparently she must have left something on because she said the car was so dead that even the doors would not unlock with the remote and she had to manually unlock the door. Once inside, there were no lights at all and, obviously, no response from pressing Start. I've only been following this forum for about a year but I seem to recall threads that indicate that since the Prius 12v battery is so small, once it is completely discharged it suffers great damage. Do I remember that right? If it takes purchasing a new battery, I'd rather do that than possibly leave her in harms way with a weak battery doesn't hold a charge well in the future. All opinions appreciated! Thanks!
The AGM battery in the Prius does not like to be deeply discharged. It is probably easiest to replace it for best reliability. You may be abke to recharge the old one but it will likely cause issues again.
I’d get a new battery. One option would be to keep the battery and forgo the core charge and put it on a charger to see if you get more life out of it . Then I’d investigate the daughters mistake to get at the root of the replacement . It will lead to the best piece of mind.
Thanks -- the daughter's mistake was to leave a dome light on. She did the same thing in my wife's car several months ago. I used Facetime to show her how to correctly jump the car, which was successful. I'll replace the battery when I next visit her. In the meantime, I had her leave the car in READY mode so that the 12v battery can be charged. Any suggestions on the number of hours for that?
I would say an hour should be sufficient, but that depends on many situationally specific factors . The longer the better though.
I would think a couple of hours would be good. One of these is a quick way to see if your battery is charging and after shutdown to see if it is charged. http://www.amazon.com/INNOVA-3721-Battery-Charging-Monitor/dp/B000EVWDU0/ref=pd_sim_263_4?_encoding=UTF8&pd_rd_i=B000EVWDU0&pd_rd_r=DNPXYWYV2RVRXAZGQR59&pd_rd_w=SVgTh&pd_rd_wg=poXcl&
Thanks for the quick reply guys! She's actually going out today so by the time she gets back it will be about seven hours. Sounds like that should be plenty.
The original battery in my Prius became fully discharged. It was never the same after that. I was fortunate to find a post on this forum showing how to install a larger Group 25 AGM battery. It isn’t a difficult job, and you don’t need any specialized technical knowledge. Replace OEM 12V battery with Group 25 AGM | PriusChat I’ve just added a few notes to that thread.
I have left the power on for several hours by accident and when I came back to the car my battery was still almost full, so there may be a more in-depth problem
