How do you replace the 12v battery?

Try running the test and post all three values. The 14.3 test only shows the voltage on the bus while the DC to DC converter is running (ready mode). The test is best performed after the car has set for a few hours not running.

Three steps in test.

1. Accessory Mode
2. Ig On Mode
3. Ready Mode

DO-IT-YOURSELF TEST PROCEDURE (thanks to jdenenberg):
- Without brake pedal, press the Power button once and release to enter ACC mode
- Press and hold the MFD Info button, then turn the headlights on and off three times to enter Maintenance mode; release Info button
- Press “Menu” (on screen)
- Press “Display Check”
- Press “Vehicle Signal Check” - the battery voltage is shown and should be about 12.4 to 12.8 Volts (normal for an unloaded battery)
- Again without brake pedal, press Power button and release to put a current load on the battery - the voltage should stay above 12.0V (if less than 12.0V the battery is not well, or there is a fault or unusual load somewhere)
- Press brake pedal and press Power button once to enter "Ready" mode - the battery is now charging at about 14V (if less than 13.6V or more than 14.4 there may be a problem with the charging circuit)
- Turn car OFF to leave Maintenance mode

Source: Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

Thanks for the reply.

 

I hear ya.

Post all three values that you get in the morning after the car has set overnight.

FYI, a fully charged Optima should measure 13.1 volts as per Optima Jim (Optima rep who post's here on PC) straight out of the box with a digital volt meter measured at the battery post's. I don't doubt they told you it was fully charged when you bought it.

Do you ever get up around Columbus? I was raised in Gahanna, born in Cleveland. Class of '73 Lincoln High School "Go Lions!"

 

That's a fairly reasonable price for the Yellow Top. The price was raised here recently, but it does seem to fluctuate. I see it for $209.99 plus the $15 core charge without using a online discount code from Advance Auto

Advance Auto Parts: Shopping Cart

If you use the discount code A124 the price drops to $184.99. The discount code is only good till the end of the month.

Source of codes: Advance Auto Parts Coupons and 40% off Promotion Codes – 2013

 

Ok, based on the knowledge I have obtained here on Prius Chat and elsewhere I will say this.

A fully charged AGM battery should read at least 13 volts measured at the post's with NO load with a digital volt meter. Note: The Prius does require a AGM type battery AND the "yellow top" is a AGM type battery.

Furthermore, normally a fully charged AGM battery usually reads close to the following figures when running the test on the MFD.

Accessory Mode: 12.6 volts or higher
Ignition On Mode: 12.4 volt or higher
Ready Mode: 13.6 to 14.4 volts

Based on that information, it is my opinion that your battery is simply not fully charged. It would be a good idea if you were to connect a battery charger to the battery at the post's or simply connect one under the hood at the jump post in the fuse box. However you do it, make certain that the polarity is correct BEFORE you start the charging process. Also, if you do charge the battery use a "smart charger" that has a AGM setting on it. Some folks will say to charge it slow, other's will say charge it fast. I recommend you charge it at 4 Amps and let the charger run until the charger says the battery is fully charged.

I know you said that the folks who sold you the battery said it was fully charged. However, it does appear that the battery is not fully charged, otherwise your readings would be much higher.

FWIW, the number's I posted above are what I see on the MFD in our 09 Prius after it has set overnight. The battery in that car is a OEM battery that was purchased and installed in January of this year.

Finally, as I posted earlier, Optima Jim who post's here on PC from time to time is a representative for "yellow top". He too has said that the "yellow top" should measure 13.1 volts with no load when fully charged. With that said, it sounds like your battery is not fully charged.

 

Here in the UK its not to expensive to have Toyota fit the correct battery at £90 inclusive but as I needed the car and they could not do it that day I decided to do it myself. A national retailer euro parts has a website where you enter the car registration and it recommends the correct battery. Bosch have a good reputation and at £58 not too expensive. After removing my battery I discovered the new Bosch battery was too small so back to the store where they recommended an Exide Excell battery which matched the original but now cost £69. When I returned to my car which I had left unlocked the rear door/lid had locked itself so I had to fit from the rear seats! The battery is now installed but it does not have a suitable vent hole to fit the vent pipe in fact the battery has vents at either end neither of which are designed to fit a pipe of an sort. Am I or the car in any danger?

Galaxy Nexus ? 2

 

You can buy battery chargers at most auto supply and a lot of retail outlets. There are quite a few out there. The main thing is you want a charger that has a AGM type setting and adjustable amperage. Pep Boys might have one, and if you were to ask them nicely they might even exchange the battery you have for a brand new one. What happens with batteries is if they sit on a shelf for a long period of time they will discharge.

I see online that Wal-Mart list's a store in Cincinnati. You might try there, and see what they have on the shelf. As long as you buy one that has the AGM setting and has the switch to adjust the amp's, you should be Ok.

 

This reply is in answer to Mathew jg above.

Although I can appreciate the merits of an Optima or other non-OE battery, whether these are superior 'spec. or same 'spec but lower cost, I find myself in agreement with the 'fit an OE battery' view. I just can't see that the gains are that worthwhile in doing anything different (though I appreciate that superior designs of battery from an electrical point of view are available).
If the battery that you have fitted has no vent pipe then the hydrogen given off as the battery operates will accumulate somewhere, rather than be routed outside the interior of the car. The will be a safety valve of some sort if there is no vent. Probably not talking large amounts of H2 but the best option is to have a vented battery - as effectively it is positioned in the passenger compartment, and it is also near to the main NiMH hybrid traction battery.

 

Definitely specially in the UK where the price is quite reasonable and given the hastle that I had getting the right size etc. My message to anyone in the UK is get Toyota to supply and fit the battery to avoid my experience

Galaxy Nexus ? 2

 

Its not a major job but it is a bit awkward. Not worth doing in the UK unless you can get the battery really cheap. It took about 45 minutes to fit but many hours to find a battery with the correct terminals, correct physical size, correct terminal layout so that the strange connector can fit and fie whatever reason I ended up using several tools. Definitely recommend a magnetic pick up tool for when the screws fall into the bottom of the battery shelf.

Galaxy Nexus ? 2

 

I think you pretty much answered your question, the longevity of the life span will probably be reduced.

12 volt batteries naturally discharge if they are allowed to sit idle. If they are allowed to discharge considerably, then there is a chance of sulfate forming on the plates. This causes even more problems when trying to charge or recharge a battery to 100% SOC (state of charge).

I understand everyone has a budget and I do respect that. Take the time to do some more research on 12 volt batteries, maintenance of said batteries, and when you can afford one get a decent charger to add to your arsenal. You will probably find it will be used more than once.

 

Wow, that sucks for sure. First time I have seen that posted here on PC. I haven't a clue of what to say, but it is obvious that water appears to be entering there.

I know you bought the car used. I would have to wonder if there is hidden damage due a possible collision that happened before you got the car.

Most folks are reporting the water coming in around seams in the sheet metal around where the struts for the hatch are connected. Some are also reporting cracks around the molding on the roof close to the hatch area. There are also a few reports of the rubber seal leaking on the hatch as well as water coming in around the tail lights.

Hopefully someone else here on Prius Chat can help you with the leak. Like I said, that is the first time I have seen that posted here, but there are other's who have been here a lot longer than myself.

Glad to hear that Pepboy's helped you with the charge.