2012 Prius V would not start without being 'forced'

Try changing the fob batteries.

 

It's obviously the semicranial auxiliary ambidextrous flux gate. A dealer will charge you $7000 to repair it. I'll give you $500 cash for the car today!

Obviously just kidding. If changing the fob batteries doesn't work, the next candidate is the 12V battery. You have a few options with that: a) charge it, b) disconnect and charge it, c) replace it. None of these are hard but after reconnecting and/or replacing the first start will be unusual quite possibly.

 

how is the 12v health?

 

I forgot about a bad brake switch. The method you use may bypasses it.

 

Is there a website describing that method; sounds interesting.

tongue-in-cheek “idea”: solar wind?

 

Today’s electronic load testers are good for testing, not only voltage, but the overall viability. DIY level testers are available, and battery retailers will often have a pro-level version, be willing to run the test for free. It’s a 5 minute procedure. Dealerships have them too, and independent garages. Dealerships more’n likely will ding you a half hours labour for this test though.

I use a Solar BA5; see the current iteration is BA9, comes in at $75 CDN for me on Amazon. That’s probably around what the dealership would charge, for ONE test, if you want to rationalize the purchase.

The tester requires direct connection at the posts, and “needs some information”: the battery format (conventional lead acid, conventional case AGM (Absorbent Glass Mat), spiral-wound AGM, Gel, or…), and the specified CCA (Cold Cranking Amps). It can also work with Cranking Amps, some other ratings.

You hook up, enter the info, run the test, and it shows actual CCA, plus a verdict. With the Solar tester the verdict can be Pass, Pass-But-Recharge Needed, or Fail.

Typically you want to see as-measured CCA well above spec’d. CCA. Voltage, while not as critical, will be at least 12.5 with a healthy/viable battery, and a really good shape battery 12.7~12.9, with AGM’s towards the higher end.

Thanks! here’s a link for that:

How to Re-Start Your Second Generation Prius | YourMechanic Advice

 

Auto Zone has poor management and that rolls downhill.

 

FWIW, my final bottom line on testing: pull the ground to get an accurate result.
(Sadly, none of the places I went to for a test did that. Not even the dealer.)

 

I am wondering what the downsides are to running with a weak battery? Recently, my sister's 2014 Prius V would intermittently not respond when pressing the start button (a problem solved by installing a new battery) but it always ran well when it did start. How frequently is battery testing advised? How long should a battery be expected to last for a Prius driven 10k miles per year?

 

No real consequences of a weak 12v battery once you replace it. Running a weak 12v battery means it will discharge quickly when not used for a short time. This may cause occasional no starts. In extreme circumstances, a weak 12v battery can lower mpg until you replace it. A 12v battery life is determined more by age than miles. Seven years might be an average life.

 

I agree with others that there isn't much of a downside to a weak 12v battery. I would recommend a smart charger like the CTEK multi us 7002 that I bought off Amazon in 2013. I'm sure there is a newer version now, but mine cost $96. It has successfully charged many batteries without fail so far ten years later. Our 2014 prius is driven less than 10k a year and is still on its original battery. That is the norm and not the exception for the Prius. One time my wife turned off the car and then pressed the start button without pressing the brake and ran down the battery by using the heater, but the CTEK easily charged the battery and got her going again. Years later, no issues. AGM batteries like the Prius has can be deeply discharged multiple times and brought back to life by a smart charger. Just hook the charger up and let it do the work as it analyzes everything. It has saved me thousands of dollars in battery expenses.

 

We use a CTEK 7002 smart charger and charge state LED telltale connectors on the ‘fleet’.

 

As per instructions, I had disconnected my 12 V battery a few years ago to install a backup camera in my 2012 Prius. I had some problems with hardware in the kit and had to get back to the source to get replacement hardware. I think the battery was disconnected for about 3 days. Upon completion I reconnected the terminals and tried to start the car to check the new camera install. Well NO go. I had a message on the display regarding an issue with the hybrid battery. I freaked out knowing how expensive they are. Mind always goes to worst case scenario. Shortly after I got the car to start and the message did go away. I have no idea what happened there but apparently the Prius does not like its 12 V battery disconnected for long periods. Scared me. Is that normal? And yes I have had local shops refuse to work on my Prius. They say management won't allow it.

 

Pretty normal. Requires a couple tries to let the system initialize.