Do I need a new 12v battery?

If you were in the US, I would recommend one of the following:

Optima DS46B24R Optima battery direct fit replacement for Prius 2004 + , Prius v & Plug-in Prius with Instructions has detailed instructions

Exide AGM Car Battery (Group S46B24R)

List: Battery - Automotive - 2010 Toyota Prius | O'Reilly Auto Parts

I do not know my Australian retailers, but I would think S46B24R is still the buzzword for the battery you want.

It should be an externally vented AGM battery with JIS posts, although adapters exist for SAE posts.

http://ep.yimg.com/ca/I/elearnaid_2271_490138

 

Yes, the 12V battery needs to be immediately replaced. After that is done your car should behave normally again.

 

Except maybe for checking the main cable connections at the battery, no further testing is required as the numbers you are seeing clearly shows a failing battery. I'm surprised that the car still runs at all.

I'm not sure about the standard test voltages that you quoted but your numbers are WAY low.

If it will make you feel better, find a place that sells new batteries that fit your model (an AGM type is highly recommended) and then ask them to test your old one before replacement. It should fail the test miserably.

 

Since the computers test the car before it is READY, all tests are done using the 12 volt battery. So there are no tests OF the 12 volt battery. The techs just look for errors in the tests. They will almost never diagnose a 12 volt battery issue. (before we realized this, a lot of issues went unresolved, then when we did, we tended to over diagnose 12 volt issues. I thinks we have a better balance now)

 

The car is throwing the big red exclamation point on the dash when you make the car ready too. Its the only warning you get the battery is dead.

And yes when my original battery stated to failed it went rather fast within 2 months.

How many times have you had to jump start the car?

 

Sort of. What you are measuring while the car is running is the charging system voltage, NOT the battery voltage.

One sign of a weak battery is a rapid voltage drop to below the nominal 12.6-12.8 volts after the car is turned off.......and it stays down there.

And shops typically don't check 12 V batteries.......in any vehicle.
You would think they would wise up and start checking all the hybrids that come in.
After all, they stand to make a few bucks on the deal.

 

Your very stubborn lol.

Yes as Pat posted you need to replace that battery asap. Only measurement that really is important is the load measurement as thats when the car requires that batteries participation. Its measuring very dead. Your first post measurements are ridiculously low and surprised the car boots. Next step is it will leave you somewhere. Be very very careful if you have to jumpstart this car.
Hundreds of posts where people have damaged the car to $4000 worth of electrical damage. Its the car's achilles heel.

Replace now.

 

if it makes you feel any better, a 7 year old battery will need to be replaced sooner than later. it will be money well spent to do it now, rather than after you've broken down on the side of the road in the middle of nowhere. all the best!

 

Wow....$2500. Understandable to make sure. In the meantime try to find a decent mechanic other than the dealer as about 75% that the car needs is just basic maintenance and my dealer here gets $125 an hour. My mechanic is $75 but at least I get to talk to the guy and tell him whats going on directly. Ask around for a good local guy.


What did the dealer do for $2500 please?

 

Well if you care, then take the battery out and look at it. The original battery is made by GS Yuasa and has a date sticker on top (hidden by the battery bracket) in DDMMYY format. And if you are able to take the battery out yourself then you can replace it yourself and save the dealer labor charge.

Regarding the 80K km and 90K km services costing $2,500, that sounds like an extreme overcharge situation since the service primarily consists of inspections. In the US, new tires would be ~$500 while the front brake job would be ~$500 (in USD). It is also unclear why a front brake job was even needed at 90K km (which is 54K miles) unless the front discs were extremely rusted due to lack of use.

 

i guess someone from down under would have to chime in here. perhaps it's just more expensive than u.s.?

 

It is certainly possible that auto repair prices in Australia are higher than in the US. Regardless, the OP's car needs a new battery and that need will not change just because the OP may have recently paid an excessive amount for service.

Maybe the high repair prices will motivate the OP to learn to DIY.

 

Right now $1AUD = $0.94USD

 

That's not a bad conversion.