2005 Prius replace Auxillary battery

I doubt that you will be able to order the 12V battery from an online Toyota dealer parts dept due to concerns about shipping hazardous material. Battery MSRP is $139.

The battery is AGM, hence it should have little or no free electrolyte inside, and is packed in so much shipping material it is a bit ridiculous. Nevertheless I believe that most dealers selling parts over the web will not ship the battery.

 

The Prius 12V battery has non-standard battery terminals that are much smaller in diameter as compared to a regular 12V battery. You will not be able to find an exact replacement battery anywhere (in the US) other than at a Toyota dealer.

If your husband is willing to mess around with installing replacement battery connectors, then a yellow-top Optima battery of the correct physical size could be considered as an alternative. However the total cost including connectors will probably be greater than $139.
For example, see: http://www.elearnaid.com/12vo1topraub.html

 

You can also see my method, which now has been intalled for 10 months with no problem. It also requires modifying the connectors. This is a little more DIY then the Yellow top, but a lot cheaper. Some auto stores stock the yellow top, but not the adapter kit. You can order it on line.
http://priuschat.com/forums/gen-ii-...66601-battery-replacement-economy-method.html

 

I just replaced the original battery in my base 2006 Prius (98K miles) with the Optima 51 Yellow Top and the elearnaid adapter kit. The elearnaid kit came with everything needed and was shipped in 3 days . It cost $16 more than the dealer battery (which was quoted as $139 + tax = $149). The kit came with detailed instructions including a list of recommended tools, which was very helpful.

My mileage was 52-54 mpg last week (with the original battery reading 11.9 - 12.0 V in accessory on mode) and was 54 yesterday with the Yellow Top (reading 12.6 - 12.9 V in acc mode).

So far, it's working well and I'm glad I chose the Optima.

 

There's almost always a 20% off parts coupon available at my two local dealers. After trying to get one installed by CarX (and failed due to the idiots swearing they had the proper size and had done it many time before on a Prius II). I eneded dong the install myself (dealers wanted $100). Took me 15 easy minutes (not at all the usual a nasty job, because the battery is perfectly clean,inside the car, in the right rear trunk area).

 

Really dumb question. How do you know when it is time to replace the battery? Is it like on a regular car where the internal combustion engine will not start?

 

I'm sure other more knowledgable people can answer this for you. I don't think the Prius works like this. Greetings from Vista! Heading out to Cardiff beach with my dog today.

 

Almost every battery I have ever tested, later proved to me that it was going to fail IF it only read the rated voltage. ie: 12 volts. With a flashlight it is not so critical but a car it definitely is.

 

Hi All,

The battery that Elearn-aid sells is also sold at Advance Auto. It took some on-line detective work to figure that out. I had bought the adapter kit some months before, from Elearn-aid, to be prepared. Then found one of the local Advance auto parts stores with a newer stock battery. It was definately more than $135, altogether, however. But, I had it done in a few hours on a weekend.....

 

Eventually, but first you'll most likely get any number of random symptoms of other phantom problems. The two things that will *not* happen are the rr-rr-rr of slow cranking or the click-click that happen with conventional drive cars; this is because the Prius 12V battery does not directly crank the engine.

If the battery is more than 4 or 5 years, or if it's ever been drained for whatever reason, test it. E-Z do-it-yourself procedures are given here:
http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html

 

The voltage on my scanguage usually reads 13.2 volts. Would the scanguage show the voltage dropping to 12 volts indicating the battery needs to be replaced?

 

In "Ready Mode" (ie when you are driving your Prius) the voltage should read about 13.8 volts (the inverter is charging the 12v battery). When in ACC (Power on without touching the brake) the voltage should read about 12.5. Your 13.2v is a strange reading. Use your MFD in maintenance mode or a digital voltmeter to read the battery voltage directly.

JeffD

 

I am guessing that you are using the scanguage in ready mode, if so, you are looking at charge rate. Use either the self check on the car, or buy a multi-meter, digitals are available for less than $10.00. Incidently no instrument drops voltage, they read voltage. Voltage is only dropped across a load ( a resistor, lamp, radio, etc. ) In the quiessent state, that is no load, not in ready, the battery must read something more than 12 volts.