12V battery how long does it last?

I know it is an old thread, but it is worth while to see how long they can last. My 2009 is still running the original 12v. 8 years and it shows no signs of failure. My car has been indestructible except for a hailstorm that left some dings in it. I just can't get rid of a car that has never given me a bit of trouble. I bought a new yellow top last fall thinking it couldn't possibly make it through another winter. Here it is a year later and the yellowtop is still sitting on the shelf with the battery tender keeping it up.

 

Well just to finish up on my test of how long a 12v battery can last I pushed my original in my 2009 prius until it finally gave up the ghost. I knew it was weak for the last 6 months or so, but I wanted to see how long I could go. I kept one of those jump starter battery packs in the car once it started getting weaker. I had to jump it twice in the past week so I figured that was pushed as far as I could.
Not bad getting 10 years and 175k out of the original Toyota 12v battery. I never got that many years in any other car in my life.

 

Interesting. I just replaced my dying 12V with a Yellow Top. On a cold measurement, it reads 12.73 V direct. A cold measurement In Diagnostic mode, 12.1 V. Not sure why. According to the AGM battery tables I have seen, the Yellow Top is at 90-100% state of charge. Whether the Diagnostic mode is working correctly, I can not say. Even at the front Battery terminal under the hood, the Yellow Top only drops 1/10 of a volt with all that wiring inbetween.

 

12.73V = no load; a meaning less measurement.
12.1V = some load via diagnostic mode.
If a meaningful load was applied, this battery was likley in 10-11V range.

Read Post #5 & #8 to learn how to apply a meaningful load to assess the 12V battery health. Is my inverter coolant pump slowly failing? | PriusChat

 

Does anyone know what 'load' is being applied during Diagnostic?

 

that would be useful info. i don't recall others reporting that big a drop. try it cold and turn the headlights on to see what happens.

 

By that you mean hooked up a multimeter, say first thing in in the morning? That's a good reading.

Not sure that it matters, or is relevant. Look into the new digital load testers. I use a Solar BA5, was about $60~70 IIRC. It applies some sort of electronic "load". Before doing the test you hook it up (the 12 volt battery powers it), enter the type of battery it is, the specified Cold Cranking Amps (or Cranking Amps, or one or two other value can be entered), then push the button, and it determines the actual CCA, AND gives a verdict.



I have the Optima Yellow Top battery also, put in in September 3 years back now. So far it's been fine. When brand new it read around 12.75 volts at-rest. Now it's about 12.6.

I'm pretty nuts about keeping it charged, doubly so since our driving is infrequent; the car often sits idle for a day or two. During those times I hook up a CTEK 4.3 charger, just leave it on for the duration of the down time.

Next time around, say around the 5 year mark for this battery, I might swap it for a convention-shaped AGM. Canadian Tire has one on offer, their housebrand, which is something rebranded. Believe it's physically identical to the OEM battery, and the specs are not bad.

 

I bought that same CTEK smart charger for my 12V battery. It brought up the Yellow Top to full capacity. Taking the advice of other members, I only check the 12 V cold. The only issue I noticed with the Yellow Top is that the carry-strap wants to get in the way of the positive terminal, so I tied it back out of the way. I didn't want to cut it off since I'll have to lift it out some day. I'm no spring chicken anymore.

 

You can sneak the carrying strap off the battery, at least you can with the 3rd gen spec Yellow Top. You just kinda push it down and twist, if I recall correctly. Then shove it in the space between the battery and the car body, so it doesn't get lost.

I use the snowflake setting on the CTEK 4.3 when charging the yellow top, in the CTEK manual it suggests to do this for Optimas. There's also "conditioning" charge mode, they suggest to do once a year. I've yet to do that, maybe should though.

 

So I know this is a super old thread, but we just replaced the 12v in our 2008 Prius for the first time in 13 years. About 195,000 miles on the car. It probably needed replacing about a year ago, but it was driven minimally (maybe 4000 miles) in 2020 so we didn't realize it. Total cost for new battery plus labor in the Denver area was $275.39 at the Toyota dealer. Just wanted to toss this out there in case anyone is wondering!