Got a Prius 2011 from an aunt who didn't drive it much. It sat in my driveway for about a month and wouldn't start. I took out the battery (a Truestart GSYUASA with the 84 month sticker), and charged it back up using a Deltran Jr. After it's apparently fully charged, the multimeter reading read 12.54. Went on a short grocery trip and the car sat for about 3 days, took another voltage reading while it was connected to the car, and that read 12.10. From the 12v battery charts on this forum, my understanding is that the capacity of this 12v is not as good as a new one? And should the 12v be losing that much power while sitting in the car like that? Would turning off SKS help with battery drain? EDIT: Aunt also says the battery was changed in about 3~ years ago, but at a dealership in Las Vegas. I live in L.A. county now, anyone familiar with how warranty on a battery works in this case? (if I can even claim it at all)
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.
Am I better off getting a deep cycle battery like the Optima yellow top? Are those still well regarded?
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.
I don't have a garage, so I'd have to run a long extension cord out to my front yard and charge that way I guess. "Part # 51-440BAGM" (I can't post links yet) This is the battery you are talking about right? Looks like there's a rebate + 25% off coupon I can use. Thanks for the help!
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
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
