will my 12v battery be alright?

Not sure why your doing it like that. Does it have a full charge green light?

At 3 amps it will take forever to reach full charge 13.6 volts.

but if the best it can do is 12.1 Buy a new battery It’s done imho.

I’m glad you asked I have not tested my 12 volt battery in about 4 months.
I just checked it’s sitting voltage after driving a lot today and it’s 12.4.
Not good.
It’s a optima yellowtop last one I had failed my load test at 2 years 11 months and 23 days on its 3 year warranty. They gave me a new one. This one is at 39 months so is now on my shit list.
I am doing a load test as we speak.
Stand by....

 

I’d second this; it’s toast.

 

Ok so my very benign load test is with the car off measure the sitting battery voltage.
Write that down.
Then with car still off turn on the headlights in high beam for exactly 5 minutes. Then shut the lights off wait 2 minutes. Measure again A healthy battery will not drop one volt after a few minutes of recovery,

Right now mine measured 12.10 so now I know it’s getting tired and should be watched.
I will try a 20 hour recondition mode charge see if that helps but my verdict is yellowtops suck.

Your 12.1 battery will fail this test miserably. Try it and see.
Your 12.1 will measure 11.2 maybe lower which is right in the zone of oh no start. Prove me wrong please with this test.

I try to stay on this cars 12 as it’s mamas car and my methodology works I have never gotten the I’m stuck call in 14 years of g2 ownership.

 

Think I'm going to try a Batteries+ Duracell SB battery this time. Its a got a 48 month warranty and yellowtop is 36 months & more expensive and is doing some sketchy stuff just like my last yellowtop at 3 years.

That's the thing with the Prius G2 12 volt battery you have to be involved and proactive with it or it will leave you at the worst time.
Which is counter to this car as for years its will be just perfect. I try to throw the charger on all my cars every 4 months.

What kills everyone is the Prius G2 12 volt which is and always has been the #1 post on this site. Because lots of stupid shenanigans happen when it fails. Its bolted down in a bad spot.

They also got a nice 24 month cheap 12 volt that fits the Prius if your broke.$139.

I was in my local B+ the other day and the battery display is impressive. I asked the guy if the SB models sell good and he said there flying off the shelf. There must have been 30 fresh of them all lined up on display.

Duracell pretty good warranty 48 months.I'll try it I'm done with Ytops.

Check it out:

Search Results for prius car batery at Batteries Plus Bulbs

 

AFAIK the Duracell AGM batteries are made by Deka/ East Penn- seem to be decent quality.

Posted via the PriusChat mobile app.

 

NO. Not necessarily.
If the battery is getting weak it could fail at any time.
And what if the problem really is a bad main connection and not the battery itself ?

 

NOT good. Start shopping for a new battery.

 

Charged my yellowtop last night it eventually turned on the green full light.

Drove it around today and it measures 12.4 and not doing real good on the headlight test.
So it’s a little sketchy. In my limited experience The problem with ytops when they get past there 3 year warranty they seem to fade fast.