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12V battery how long does it last?

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by whodat, Apr 19, 2010.

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  1. whodat

    whodat Member

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    I've got a 2006 Prius that gets driven almost every day. How many people have never replaced their 12V battery yet and have older Priuses?

    Thanks
    Dave
  2. oxnardprof

    oxnardprof Member

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    My 12V battery died just two weeks of the anniversary of my pruchase.

    I bought the car March 31, 2004, and it died shortly before that.

    The mileage was about 99,000 miles; I was planning on replacing it at my next oil change.

    I had to replace it myself. As you have seen from other threads, this is relatively easy, but for me it took about two hours. I am only moderately handy.
  3. bisco

    bisco cookie crumbler

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    our 04 has 70,000 and the original battery and currently getting 56 mpg.
  4. jdenenberg

    jdenenberg EE Professor

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    Dave,

    As in most things, it depends. If you take good care of the little 12v battery, it can last a long time. My 2004 Prius is at 172,000 miles and still has the original 12v (and traction) battery.

    Things that shorten 12v battery life are:

    • Full discharges - a small number of full discharges will destroy most lead acid batteries.
    • Storing the battery at less than a full charge - leads to "plate sulfation" which weakens the battery, but can be reversed using a "Battery Tender" (~$60) as long as the battery is not too far gone.
    • Not driving on long trips - Our Prius charging system is a constant voltage system which safely avoids overcharging, but is a very slow charging system. Short trips tend to discharge the 12v battery.
    • Using a high current battery charger - Don't charge our little 12v battery at a current higher than 2 amps. Again, a "Battery Tender" is a good purchase.
    JeffD
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  5. qbee42

    qbee42 My other car is a boat

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    Pre-dead. That must be a dealer installed option. :D

    Tom
  6. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Jeff, if you use the diagnostic menu on the MFD, what voltage do you see from your 12v battery?
  7. jdenenberg

    jdenenberg EE Professor

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    Usually 12.4 volts with no load and just over 12v with accessory load (second press of the Power button without the brake). I have seen it a little lower after a short trip.

    I can't actually do the test right now, my MFD just exhibited the classic failure mode this week. :(

    I'm considering an Optima yellow top in the fall as a preemptive measure, but maybe I'll stick with the original to see how long it will actually last (that's the engineer in me talking).

    JeffD
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  8. halpos4

    halpos4 "Taxi"!

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    I changed mine on my 06 Taxi at 240,000km [150,000 miles]it started displaying the traits of a dying 12v,but i believe i was to blame for it's early demise in that,when i'd pull up to a hotel to pick up passengers instead of turning off the lights i'd just power off,headlights would turn off but parking lights would remain on,i did this for three years but when i noticed dashboard display lights were really dim it was then i started to turn off my lights when leaving the car even for short periods,since replacing the 12v,i'm now in the habit of switching off my lights all the time when leaving the car..so we'll see how long this 12v will last,
    I replaced the original for a Genuine Toyota 12v,my 06 now has 288,000km on the odo.
  9. rcf@eventide.com

    rcf@eventide.com Member

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    I changed mine after five years and 85,000 miles of "normal" driving in NJ, where we have winters and summers, although neither is extreme. There was no sign of trouble with the battery, but I felt that it was unlikely to live for the next two years that I expect to keep the car, so why not replace it now instead of waiting 'til there was a problem.

    After the exchange, I tested the old one and found that it had about 2/3 of its rated AH capacity remaining.

    Richard
  10. whodat

    whodat Member

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    Agreed. I've got 120K miles and my commute is 1 hour (50 miles) one way. (2 hours 100 miles round trip). I only use a battery tender which I have observed takes about 3-4 hours to charge the battery fully before going into float mode.

    Dave
  11. James Luckett

    James Luckett New Member

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    Mine is a 2008 and I think it's time for replacement. Well over 100,000 miles. Cold (20-deg F) it's reading about 10 volts on the dash display. After driving short distance, it comes up to 12.0, never higher, and when it sits it returns to 10 volts, and drops into the high 9s if I go into accessory mode.
  12. JC91006

    JC91006 Senior Member

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    You are most definitely due for replacement.....yesterday!
  13. dorunron

    dorunron Senior Member

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    10 volts and dropping to 9 signifies a shorted cell, probably sulfated. You should replace this battery now.

    A fully charged AGM type battery should read a minimum of 12.8 volts measured at the battery posts with a digital volt meter with NO load attached.

    Running the test with the MFD the screen should read as follows with a fully charged NEW AGM type battery.

    Accessory Mode: 12.6 volts or higher
    Ignition On Mode: 12.4 volts or higher
    Ready Mode: 13.8 to 14.2 volts

    Battery SOC Chart.jpg
    toddrav and GrumpyCabbie like this.
  14. anotherOne

    anotherOne New Member

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    Our 06 went six years before that battery died. Oddly enough, it was just after a 2 hour trip. The replacement (done by Toyota), died two years later.
  15. toddrav

    toddrav Junior Member

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    I have a 2007 and think the battery has been poor for some time. After recently experiencing several unexplained 'failures to start' with the red triangle on, I rediscovered Priuschat and tested the battery and it dropped quickly down into the 10V range with the lights on. I quickly ordered a Yellowtop off Amazon and am waiting for it to arrive.

    After swapping I'll try using a 'battery tender' to see if I can recover the OEM battery and keep as a backup.
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I suggest you fully-charge the Optima prior to installation as several members have recently posted that their new batteries arrived in a discharged state.
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  17. toddrav

    toddrav Junior Member

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    My foray into DIY battery replacement isn't going smooth.
    I bought the D51R off Amazon, which I swear I had read was drop in replacement.
    To the auto store tomorrow to get the proper sized clamps, wire, etc.
  18. dorunron

    dorunron Senior Member

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    Not a fan of the "yellow tops", but I think the D51 is not the correct battery.

    If you are going to deal with Amazon and use the "yellow top", the battery listed below is the correct battery for the Prius.

    It has the JIS posts that are reversed with the negative post being to the right hand side when the posts are closest to you. It should also have the vent hole in the correct location.



    The battery part # is DS46B24R

    It is a true drop in battery with the correct post configuration. The D51 has standard SAE posts on it. That is why it doesn't work with the existing clamps on your Prius.

    If the Prius you have has the original battery in it, the DS46B24R should fit it without having to change anything. One other thing, if your car doesn't have the SKS (smart key) on it, the tray should be changed or you will have to mod the hold down clamp as the new battery is larger than the OEM.

    Hope all of this helps you.
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  19. toddrav

    toddrav Junior Member

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    Your comments are spot on.
    However, I went ahead and installed the D51 - it was a DIY beast because of the post placement. Fortunately I already had the larger tray.

    Strongly recommend nobody else try kludging in the D51 since I had to flip the battery around to get posts in right position and overflow drain, which then required longer cables. It was difficult to place and I needed to add several bits of insulation to keep safe.
  20. howardc1

    howardc1 New Member

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    What are you trying to say?? You bought the car on March 31, 2004 and it dies SHORTLY BEFORE THAT....really, your battery died before you bought the car?? You also talk about "two weeks of the anniversary...." WHAT anniversary? 1 year, 10 years? Not clear what you are trying to say,.
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