12 volt battery question

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Opensesame, Jul 7, 2019.

  1. Opensesame

    Opensesame New Member

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    2007 Prius
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    History-
    Car has 130k. Battery is a 4 year old Duracell ultra (listed as an option for my Prius from a few different shops) that I purchased new and installed myself. It has worked fine since installation 4 years ago. 2 years ago I added a trailer hitch light kit that has its own ground screw.

    Symptoms: About 1/2 the time when I start up, radio presets have reset to default and clock has reset; occasionally the key fob doesn’t work to unlock the car or communicate with the start button; once, on startup, the gas gauge was blinking one bar even though the tank was full.

    Diagnostics run-
    the onboard battery test using the MFD indicates battery still producing enough voltage (both when cold for a few hours and with a load)
    Autozone battery tester indicates battery is fine

    I dropped car at dealer as we were going away for a while and I wanted someone else to look at it. Dealers response was:

    “Hello, xx here from Toyota. So what is going on is the auxillary battery that is in there currently is too high voltage for the vehicle to handle. The battery should be around 345 cold cranking amps and the battery is showing 450 cold cranking amps. So what it is doing is causing the instrument cluster to short out thus making the key fob not work. Once it is able to level itself out that is why then the key fob will work. So we need to start with a new OEM battery $360 and continue testing from there ,but this where we need to start. Also, technician noticed the water pump is leaking pretty good so while we are in there I would recommend getting it replaced. Cost of a new water pump is $570. It does also need some preventative maintenance, spark plugs $”

    Is that a possible explanation for my problem? That too many CCA are shorting the instrument cluster? The Duracell is listed as producing 325 CCA, and even if it did produce more, could that even be a problem? It has worked with no issue the last 4 years, including the 2 since I installed the trailer hitch light kit.

    Any thoughts appreciated.

    Thanks.
     
  2. fmerkel

    fmerkel Member

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    Complete BS.
    Think of it like a bucket of water with a hole in it. The CCA is the SIZE of the bucket (contents/amperage), and voltage is the size of the hole (delivery) + the 'fill'. You can have a big bucket but if it does not have a decent fill it won't work.

    The CCA just sit there, doing nothing unless there is demand for them, then they deliver what is needed as long as the battery is in sufficient condition to do so. Does not matter if it is larger than 'required'. That's just insurance.

    I think you need a different dealer. Sounds like you got a short somewhere.
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Did their tester show the measured CCA?

    You can cut through a lot of the Gordian Knot of battery condition, with something DIY level like Solar BA5. The new iteration is BA9, around $52 (US) on Amazon.
     
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Open,

    The dealership is totally full of crapola. No 12v battery in the world is going to have a CCA that is too high and shorts out the dash. This is absolutely ridiculous and makes no sense at ALL. A brand new toyota "sks car" 12v battery is rated for 325 cca and will test at around 475-525 cca. I have a 2015 non-sks Prius battery in my garage that I keep as a "just in case" spare. It's rating is for 272 cca. This morning, I happened to test it while cleaning the garage. It tested at 350. My actual battery in the 2007, an hour ago, with a 325 cca rating, tested at 425, and it was manufactured 10/26/2011. I would love to see them do a load test on a NEW battery and then explain why it tests higher than 450, as I know it will.

    Since they tried to tell you the battery voltage is too high, ask them to explain why the battery is at ~12.8, but when you ready the car it goes to about 14.1 due to the inverter powering the 12v bus. Why doesn't that cause a problem? OMG, I would have a field day with these fools. I would have that service advisor crying and begging for help.

    ALL your symptoms are exactly what happens when 12v is disconnected from the car. I would think the more likely problem is a poor connection between one of the battery terminals and the car. You are losing the (-) connection at the battery or where the cable connects to the chassis, OR you are losing the (+) at the battery connection or at the underhood fuse box where the cable connects to the jump point.

    If you disconnect 12v from the car you will...
    lose radio presets
    lose the auto up/down function of the driver window
    gas level indicator will default to one blinking dot until it calibrates itself.

    I would also have them show you the water pump leak. Typical evidence of seepage is a small amount of dried up pink residue on the inside of the water pump pulley. This is SEEPAGE and is insignificant. I've seen it on MANY prii. All I do is let the owner know to look at it now and then, like when they check oil and coolant levels, to make sure it's not wet. If they can show you DRIPPAGE, then I would look at replacing it.

    They're trying to soak you for $1200 so far and haven't even solved the problem you went there to have them look at.
     
    #4 TMR-JWAP, Jul 7, 2019
    Last edited: Jul 7, 2019
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  5. jb in NE

    jb in NE Senior Member

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    This is a load of nonsense. The voltage is separate from the cranking amps, and they didn't specify the voltage. The only way the voltage could get too high is if the charging system were malfunctioning, and that would happen to either the currently installed battery or to a replacement battery.

    I would just step away from this dealership, and find a shopt that is competent. These guys are fishing through your wallet.
     
  6. bisco

    bisco cookie crumbler

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    another poster with detailed 12v data of 'fine'
     
  7. Opensesame

    Opensesame New Member

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    Yes, true I didn’t post the hard data, but you can trust it was all in the “fine” range.
    Thanks for the input, all. I’ll take it back from the dealer and start by looking more closely for loose connections on my own, and if I still can’t solve it I’ll find another shop. And I’ll look at the water pump to assess for seepage vs drippage too. Appreciate the help.
     
  8. edthefox5

    edthefox5 Senior Member

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    My goodness the horseshit the dealer can come up with. Sorry you battery is bitchin' and has loads of current available if need be. That's a terrible thing as that great capacity will sometimes hurt you, because its a monster just waiting to get out.



    Sorry.
     
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  9. AzWxGuy

    AzWxGuy Weather Guy

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    I remember several threads from back in my Gen II days concerning the short negative terminal cable that runs from the battery to a ground point on the inside tailgate below the hatch. I would remove the negative cable clamp from the battery and then remove and clean - if need be - this connection point to the vehicle body. Any rust or contaminants here or a loose connection can result in poor charging and a host of other electrical problems.
     
  10. Skibob

    Skibob Senior Member

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    Not to be nosy but are you a woman? This seems to be the type of behavior dealers do with women.
     
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