12v battery finally gave up the ghost after 8 1/2 years. The symptoms were an extended brake module run time followed by a few days of having to jump start the car in the morning. I’d say that I got my money’s worth. Replaced it with genuine Toyota battery. A little pricey but proven to be a good investment
i did the same this summer at 7 1/2 years, but didn't get any warning. pretty good run, let's do it again!
My OEM lasted around 8 years too, but I was pushing it with a charger/conditioner after I bought the car in 2014. I have one of those 12V USB outlet devices plugged into the 12V aux socket under the flying bridge. It has an LED readout of voltage when nothing is plugged in and alternating display of current or voltage when something is. The refresh rate was just good enough to show me a starting voltage of 9.6V one cold February 2018 morning, so off to my favorite dealership to get a TrueStart. About $226 and 30 minutes of work later problem solved.
I got almost 9 years out of our 2010’s before replacing it. Didn’t push it as far as you did, but before it left me wishing I hadn’t. Nice avatar pic btw.
Interesting. I think these experiences go against the common thinking that the Prius 12 volt has about 1/2 that lifespan. I think a challenging aspect of the 12 volt in a Prius is that it actually doesn't crank over a "starter". With a regular ICE vehicle, you'll get ample warning that your battery is weakening, simply by "how" it's starting your vehicle. If it starts cranking slow, you're pretty much being warned battery failure is on the immediate horizon. With the Prius 12 volt, it's "booting" up the system, awakening the HV battery. Also, the 12 volt with a Prius becomes a bit of a Gremlin Catcher, as the recommendation to replace it, becomes almost automatic if anyone starts to experience symptoms that are hard to trace to direct cause. But those are impressive runs for the battery. I don't expect to get near that lifespan out of my Honda Fit battery, which I'm already nervous about, since it is about the size of a motorcycle battery.
Older cars did warn you by cranking slower, especially on a cold morning. It's been my experience the last several years that they no longer do that. I had a couple that worked one day and clicked one time the next day. Seems to be all or nothing now. I'm not referring to the Prius though, mine did actually give me a warning on the instrument panel for 2-3 days..."accessory battery is low".
My 2010 (purchased early Nov) has its original battery. May 2010 date code iirc. It's obviously weak, but hasn't caused a problem yet. This weekend, I put a (fused) charging pigtail on the battery and started charging at every opportunity with a (Pulsetech) desulfating charger. I have had excellent luck restoring sulfated flooded electrolyte auto batteries with this charger... it takes a while (4 - 5 weeks)... but I've brought otherwise unchargeable batteries back to test like new (by specific gravity, voltage, starting capability). Can't say what causes end of life in these AGM batteries for sure. If it's sulfation, I'll likely see improvement over next few weeks. For $200... My 2 minute 12V Prius battery evaluation is this: After something other than a short trip, park the car for the night. In the morning, open the driver's door, but do not turn the car on. Check voltage. The easiest way is at the charging terminal in the fusebox. I was in high 11s, pretty marginal! I'd be interested to know what you get with a fresh battery.
One difficult thing about an apples to apples comparison of batteries.....since they are replaced many years apart, getting the same brand/model as last time doesn't mean you are getting the same battery as last time.
Toyota of Whittier, CA...$217.97 before tax, core etc.. Round about $230 out the door. It is the Yuasa, Toyota branded, True-Start, 84 month. Self installed.
