Why no temperature sensor on 12V battery in Prii?

Discussion in 'Gen 3 Prius Technical Discussion' started by srivenkat, Jan 26, 2013.

  1. srivenkat

    srivenkat Active Member

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    Actually I meant to ask why is there a temperature sensor on the 12V in my 2007 Camry Hybrid but not on my 2010 Prius' nor on any of the 2004 and later Prii and now if some reports are to be believed neither on the 2012 Camry Hybrid.

    There's no separate "Technical Discussion" forum for the camry hybrid at ToyotaNation and GreenHybrid so I thought I would query here, since there are many Hybrid experts on this forum.

    Where I am getting to ultimately with this discussion is the plausibility of using the Optima Prius 12V in my 2007 TCH when the time comes for it to be replaced. The main advantage is the ready-made vent on the Optima. So, what if it's of lesser capacity, as long as it can sit in my garage a couple of weeks without being totally discharged I would be alright. But what gives me pause is the need Toyota saw for a temperature sensor on the 2007-11 Camry Hybrid 12V but not on any of the Prii (?) nor on the new 2012 and later Camry Hybrids (if some reports are to be believed). Many thanks for any input.

     
  2. szgabor

    szgabor Active Member

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    I think there is a temperature "factor" if not a sensor in the 12V battery charging algorithm ... I am pretty sure there is sensors ... see my pictures on an other thread ...
     
  3. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Thermistors cost money.
     
  4. szgabor

    szgabor Active Member

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  5. El Dobro

    El Dobro A Member

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    The air that cools the traction battery also blows over the 12v battery too, so maybe it's a sensor for the cooling air.
     
  6. jdcollins5

    jdcollins5 Senior Member

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    The temp sensor on top of the 12V battery controls the charging algorithm, 14.5V up to a certain temp then drop back to 13.5V.
     
  7. szgabor

    szgabor Active Member

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    sorry to be this blunt ... but do you KNOW this is a temp sensors controlling this or you THINK ..(I think to be clear)
     
  8. bisco

    bisco cookie crumbler

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    how do you know the hycam has one, scan gauge?
     
  9. jdcollins5

    jdcollins5 Senior Member

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    I have the Repair Manual. What is this "I think to be clear" crap ! That is totally unnecessary.
     
  10. srivenkat

    srivenkat Active Member

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    As pointed by others earlier in the post, and specifically mentioned by Ken in his below post, I realize now that the Prii (at least 3rd gen onwards) do have the temperature sensor albeit on the clamp as opposed to on the battery itself; the latter is the case with my 2007 Camry Hybrid which is what threw me off (made me think my 2010 didn't have one).

    Ken's post:
    Should it be 13.7 or 14.7 volts. | PriusChat

    So it seems like Toyota started putting sensors in as early as the 2007 ( in the Camry Hybrid) and later modified it to be on the clamp itself starting as early as 2010. They seem to have gone the clamp route on the 2012 Camry Hybrids as well, which is why some folks on the Camry Hybrid forums thought it didn't exist on the 2012 model.

    This all makes me fee much better with the idea of using the Optima Prius battery in my 2007 Camry Hybrid as and when the need arises.

    Thank you all.
     
  11. szgabor

    szgabor Active Member

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  12. jdcollins5

    jdcollins5 Senior Member

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    OK, I understand. The Repair Manual shows the Auxiliary Battery Temperature Sensor and lists the range as -40 to 215 degrees C. So it is a true sensor.

    I have not seen a ScanGauge XGauge to read this temperature directly but I can read the auxiliary battery voltage. Most of the time mine reads 14.5V but I have seen it drop to 13.5V in hot weather. Ken from Japan had a post, referenced above, that explained the monitoring of the battery temperature to determine when to reduce rate of charge.
     
  13. vincent1449p

    vincent1449p Active Member

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    It had been decoded in Torque's spreadsheet but I have not published it in XGauge. Here it is:
    Column 1
    0 [TH]XGAUGE[/TH][TH]TXD[/TH][TH]RXF[/TH][TH]RXD[/TH][TH]MTH[/TH][TH]NAM[/TH][TH]Notes[/TH]
    1 [TR][TD]Auxiliary Battery Temperature[/TD][TD]07E22141[/TD][TD]010702EA0321[/TD][TD]1808[/TD][TD]00090005FFD8[/TD][TD1]tAb[/TD1][TD]F[/TD][/TR]
    Vincent
     
  14. jdcollins5

    jdcollins5 Senior Member

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    Thanks once again Vincent ! I will check it out this afternoon.
     
  15. El Dobro

    El Dobro A Member

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    What exactly is the sensor sensing?
     
  16. jdcollins5

    jdcollins5 Senior Member

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    Auxiliary battery (12V) battery temperature. If the battery temp exceeds a setpoint the battery charging voltage drops from the normal ~14.5V to ~13.5V.
     
  17. El Dobro

    El Dobro A Member

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    Since there's no physical contact between the sensor and the battery, is it sensing the ambient air around the battery?
     
  18. jdcollins5

    jdcollins5 Senior Member

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    I do not see a drawing showing the exact location of the battery temperature sensor. The Parts Catalog describes a sensor bracket and it appears to be a battery hold-down bracket or at least clamped to the edge of the battery casing.

    Have you seen exactly where it is located?
     
  19. El Dobro

    El Dobro A Member

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    There's a link to a pic of the sensor on post#4 of this thread. I went out to the car and looked at it. It sits in the battery clamp and hovers above the battery. You can wiggle it around, so it just sits on a pivot and doesn't touch the battery at all. That's why I'm wondering if it senses the ambient air.
     
  20. jdcollins5

    jdcollins5 Senior Member

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    Either measuring ambient or the temp of the metal clamp that is in contact with the battery case?
     
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