12v battery lost capacity?

Probably a one year warranty. Any lead acid battery that is fully or deeply discharged such as happened in your case does suffer some damage. This will show up as loss of capacity if you measured it. It can also eventually result in cells loosing power through resistive internal shorts from sulfate and cell debris buildup at the bottom of the plates.

There is a slightly higher than "normal" parasitic load on the Prius 12V battery (parasitic - current draw even when the car is "off"). It's normal, and most of us don't expect to be able to leave the car parked for more than a few weeks without having the 12V battery get very low.

One fix many of us use is some type of "battery maintainer". Pearl S is hibernating through winter in the garage with a "Battery Tender" connected, for example.

 

Heat kills batteries. 3+ years in Las Vegas heat likely did the trick.

Battery warranties work on a prorated basis. The older the battery, the less credit you receive.

 

Sitting for a month, after 3 years sporadic use, I wouldn't have high hopes for that battery. Reading 12.54 volts fresh after charging only confirms that: a freshly charged AGM battery in good shape, with "surface charge", would read around 12.9~13.1.

Three days later it's fallen to 12.1? It's a goner.

No clue about warranty, but I would just move on. Maybe enter the car's data on Pep Boys, there's a Bosch battery for around $140.

 

No. From what I've read, the Optima Yellow tops sacrifice amp hours to boost Cold Cranking Amps, by having more/thinner plates. And the higher CCA is not needed.

I've got one by the way, but next time around will likely be going with a rebadged Exide (similar to Pep Boy's Bosch I think, conventional shaped AGM), through Canadian Tire, which is more inline with the OEM Yuasa, also a good pick, but pricey through dealership?

Our usage is similar to your aunt's: the car often sits 2~3 days between drives, some of which are just short grocery runs. I keep it pretty much constantly hooked up to a CTEK 4.3, which is just kicking over once it's done charging, doing a maintenance charge.

No need to remove for charging btw, just be careful to never reverse connections. I use a quick connect, wired in at the under-hood fuse box. @NutzAboutBolts has a video on that connection, pinned in the maintenance sub-forum.

 

Yeah that's the one. I checked my notes, and when I input that part number on pep boys website there's a review from a 2010 Prius owner.

If you drive the car daily you should have no problems, but if it's going to often sit a day or three, then hooking up a maintenance charger, something that just gives it an occasional "tick", will keep it healthy.

 

Maintenance charger seems to be what's needed with these weak charging systems the car provides.

Posted via the PriusChat mobile app.

 

Before you go and buy a replacement out of pocket, call the dealer about the warranty. It's pro-rated but at 3 yrs will be much less out of pocket than a new one altogether, and you're not leaving money on the table. I haven't been to the dealer in years so I don't know if they have some sort of central repair record database, but worst case scenario there's only 3 Toyota dealers here in Vegas you need to call to get a copy of the record: Centennial Toyota, Findlay Toyota, and AutoNation Toyota.

All deep cycle batteries sacrifice amp hrs in favor of CCA, and this is the opposite of what we want for Toyota hybrids

 

how is this working out with your other 12v thread? i find it confusing.

 

Mine was fine also unfortunately when I went to the dealer they said that it was in the red, but he kills it mines a 2012 so I guess it’s time I hated changing it at the dealer but it’s much easier sometimes

 

agreed, but a 2012 in florida is a disaster waiting to happen, good move.