12V Battery Already Dead on a 2.5 year old Prius?

This should be cover under regular warranty, not extended warranty. 3yr or 36k miles

 

It's pretty easy to use a voltmeter to check the voltage across the 12V battery terminals under the rear seat or between the under-hood jumper point and ground. If you measure less than around 13 to 14 volts with the car turned off then it's time to replace the 12V battery.

 

So sorry to hear....I have a 2014 C as well.....it has 32,000 miles now....I will be watching for this if it happens to me.

 

welcome!
the oem battery should have a pretty good warranty, at least pro rated, look into it.
if not, there are a few options for replacement batteries, and you'll save a lot by diy.
have you ever had to jump the car before, or is it possible you left a light on, or a door/hatch ajar?

 

I'd second checking with a digital volt meter, with the car off:

12.6 or better: good shape
12.5~12.6: so-so
12.4 or less: try charging first, and/or start shopping

For a more definitive test: dealership service department or battery retailer (the latter likely for free) can check it's Cold Cranking Amps (a more definitive test of the battery's health), give you a verdict. You can do the same test yourself with something like a Solar BA5.

Bottom line: if you're asking here, you need to read up, get a few tools. Or not.

I believe the dealership is right, that the original 12 volt battery is not covered, under the Toyota or extended warranty. For good reason: it's way to easy for owners to run the battery down, leaving on headlights, map lights, and so on.

$360~$420 installed is a little steep. Check with their parts department first, and also consider Optima, Exide and so on, they should all be around $200, at the most. The OEM replacement through dealership, Yuasa I believe, does have a warranty IIRC.

 

New vehicle batteries and tires are typically covered under separate warranties from their respective manufacturers; usually pro-rated.

 

just google it..comes right up 2014 prius c optima battery

2014 prius c optima battery - Google Search

 

Are you sure on batteries? I can imagine tires being pro rated

 

replacement yuasa comes with 2 year full, then pro rated for 6 more years. not sure what the deal was in 2013 on a new car.

 

At 4.5 years & 18,000 miles, my 2012 Prius c could not be started. The first Geico roadside assistance guy gave up on jumping my car and left me stranded (no kidding, he left in a nasty huff after trying to pull off the cover under the back seat). Another guy came out, and we still couldn't get it started; but he had a tow truck and took me to my dealer. My dealer replaced the 12V battery for $276 (plus $125 labor). 9 months later (and only 1,000 extra miles), my car again won't start (it's obviously the battery). I've now moved clear across the country, so I'm not able to return to the dealer who replaced my 12V battery. It's most unpleasant when the battery fails unexpectedly (my problems were not the result of leaving lights on), because a jump won't work. I can't believe I've had this twice in a year, I now see the great risk in having a hybrid car when they're still not well understood.

 

the problem is YOU don't drive the car enough.. if you put 1000 miles on the car in 9 months that's about 110 miles a month or 28 miles a week.... the 12 volt battery is always discharging because the computers,radio,security system and key fob are always using some juice.. a hybrid isn't for people who don't drive them.. you are better off with a 4 cly car that gets 35 mpg...by now you have damaged the high voltage battery as well since it never get to charge fully.

 

That is an ASSumption that probably is not true. The HV battery is very happy sitting with only a partial charge for long periods of time.

The point about the 12 V having a shorter life if left unattended for a long time IS true though.

AND......if a jump start won't get it going, then there is something ELSE wrong.
Outside chance that the 12 V battery is shorted such that it drags down the donor battery too.......but that is rare and the odds of it happening with two batteries in a row are overwhelming.

 

how can depleting the HV battery constantly on short trip and not allowing it to recharge be good for it... if the battery is sitting on a shelf with no draw for months I agree, it will not be damaged but common sense says running it down and not recharging it is BAD.
using the OP's numbers he is putting about 100 miles a MONTH on this car...25 ish miles a week or 3.3 miles a day ... no where near enough to charge either battery .. as far as jumping it, who knows what he's doing right or wrong, we were not there

 

I don't know HOW exactly, I just know that advice from Toyota and various battery makers AND practical experience of owners reported here says that it is NOT bad for batteries using that kind of chemistry. In fact I believe that they recommend storing the car with the HV battery about half charged.

Different rules apply than what you know about "old" battery technology.

 

Half is not empty, however. Empty batteries sitting for weeks is never a good thing, no matter what the technology.

If the 12v battery is dead, the Hybrid battery charges it up. If the trip is short to the point that it takes all of the charge from the hybrid to recharge the 12v, it's just going to sit at empty.... and then the 12v battery will discharge leaving nothing left to start the car.

 

Absolutely not true.
"no matter what the technology" indicates that you don't understand the situation at all.

Many/most/all devices that come with Lithium batteries have them real close to empty when they ship to sit around waiting to be sold. Sometimes that can be a LONG time.

 

Close to empty is still not empty... completely discharged is bad for every single battery technology. Most Li-batts ship around 10% charged at minimum.

 

Just STOP the pointless bickering please.

This part of the "discussion" started out talking about leaving the battery only partially charged.
YOU are the only one talking about running it DEAD.