12v suggestion

If it's only 4 years old, you should just charge it up and use it for another few years. These batteries normally last 6+ years easily

 

It won't leave you stranded I mean unless you're going to go somewhere and stay for days and not start the car move the car go to the store or whatever maybe even then I doubt it'll leave you stranded The minute you slip the key the hybrid battery should be applying about near 14 volts to the 12 volt battery charging it right up a 4-year-old battery should not have any trouble charging right up 11.9 after sitting six seven hours is nothing too shabby You're right at 12 volts a tenth of a volt off that could be in your measuring so I wouldn't say you have any kind of a problem it's when you're plopping down to below 11 volts heading to 10 Wake up in the morning and you're at 9.6 now no good 11.9 pretty stellar to me.

 

Keep a jump box in the car just in case.

 

Had 2 brand new yellow tops they seem to last only 3 years then tank and that's after lots of remedial charges. I was going to try the Duracell at batteriesplus they hare not to expensive and have a really good warranty.

Btw, Always measure the battery voltage at the front jump point under the hood its meaningless to measure it at the battery itself.

 

My red tops just died . They're both like 9 yes I'm shocked they've held up

 

Oh and here's a simple test while measuring at the front jump point and car OFF turn on the headlights in high beams. Whiile lights on and car OFF what does the battery voltage now measure?

 

buy the oem and install it yourself, it's pretty straightforward. +labor is never a good option, how much $$$?
and that is not full coverage for 84 months, it's pro rata after 2 years.

 

Batteries can be load tested for free at most auto supplies. Low voltage does not necessarily mean a bad battery. An excessive parasitic load from many sources or the hatch light left on will reduce the overnight voltage but is not the battery's fault.

On the other hand, any battery over seven or eight years old is suspect. Load testing tells the tale in either case.

 

You might be able to find the Yuasa other places, besides the dealership. Not saying for sure, nor the dealership is more expensive, but shop around.

 

The Prius charging system doesn't just "charge it right up". It is quite slow, and even slower on Gen2 than on Gen3. The car needs many many hours to bring the 12V to anywhere near full charge.

This is why Prii that are normally driven only short distances very commonly have chronically undercharged 12V batteries.

 

Very true.

 

Our yearly driving has dwindled down to around 3000 km.

I keep a CTEK 4.3 connected pretty much constantly. If we've used the car one day, I'll leave it till the next day, but if we're not going to driving, and likely not for a few more days, on goes the CTEK, it starts it's charging regimen, then settles down to maintenance mode, and I leave it thus.

Seems to be working: current battery went in September of 2015, tests like new.

I appreciate for some, say street parkers in particular, this isn't doable.

 

If you are mechanically challenged take it to a parts store that advertises free replacement. Not a tough job after you have done a few but ugly on the first try. More little bits to be removed that you would believe.

 

I bought this battery from Amazon 2 years ago for $140 delivered (Prime Member).
Its absolutely crazy what it costs today.

 

wow