Battery Questions

Discussion in 'Gen 2 Prius Main Forum' started by beach247, Nov 23, 2008.

  1. jayman

    jayman Senior Member

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  2. SalLema

    SalLema Sal's Pride

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    I have a question in this area as well. I am only leaving my prius for two weeks? Should I have someone start it while I am gone as well?
     
  3. jayman

    jayman Senior Member

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    No, leave it alone. You're far more likely to have problems with a trustworthy - but clueless - person attempting to start the Prius, than just leaving it alone. For example, instead of going into Ready, they'll enter Acc and drain the 12 vdc battery

    Disable SKS if so equipped.
     
  4. Emmanuel Isaac

    Emmanuel Isaac Junior Member

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    Hi Guys,

    I know this is an old post but seemed appropriate for my question regarding the 12v battery on my '06. My battery (almost 3 years old) currently shows a voltage of 11.3-11.4v on cold start after over a day sitting idle. With headlight load the voltage drops to 10.9v. Temperatures have been in the low 30s-high 20s this past week. With car in IG-ON, voltage is steady 13.8v. There are currently no issues with the car and I just crossed 150K miles this week.

    I've had VSC, BRAKE and ABS warning lights come on a couple of times spread out over the past year. They always seem to go away if I turn off the car and turn it back on, except one time that it took a couple of restarts to go away. I've had a local dealer look at it twice, the most recent being a couple of months ago and they say that the battery health is in good condition when they connect it to their tester.

    The battery was purchased and installed at the dealer in 02/15. I'm trying to get them to replace the battery under the 84 month warranty, prorated since its past the 24-month replacement warranty. The dealer says that they cannot replace it under warranty unless their test says that the battery needs replacement. He also said that if I claim warranty it would need to be installed by the dealership and I will have to pay 100% of the labor cost. The previous owner had replaced the battery every 4.5 years when it died.

    Here are my questions:
    1. Do you have any insights/suggestions about the health of my battery and if there's anything I can do to save it?
    2. Is it true that they cannot give me a % off a new battery that I can install myself while claiming the warranty?
    3. Do Toyota parts require installation at a dealership to be covered under warranty? For example if I purchase a new battery from another dealer offering a discount off the list price and install it myself, would I be able to claim warranty on it if ever my battery goes dead again?

    I appreciate your help and suggestions about approaching this situation I'm faced with. I have a decent relationship with this dealership but would like to know some facts before I try pushing them to a warranty claim.
     
  5. bisco

    bisco cookie crumbler

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    welcome!
    it is certainly worth putting a smart charger on it, then keeping an eye on the cold voltage to see how it holds up.
    does the car sit idle for more than a few days at a time on a regular basis?
    a jump pack would also be a handy thing to have.

    you would need a copy of the warranty to ascertain the terms, i wouldn't trust the dealer.

    they are probably correct about the battery having to test bad for warranty. going dead doesn't mean too much.
     
  6. Emmanuel Isaac

    Emmanuel Isaac Junior Member

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    Yes, the car typically sits for a couple of days at a stretch. Do you have any recommended chargers for the AGM battery?
     
  7. WilDavis

    WilDavis Senior Member

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    Sears DieHard #28.71219 Charger/Maintainer (~$20 on sale) use the supplied pig-tail and connect every time car is garaged!
     
  8. edthefox5

    edthefox5 Senior Member

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    Jesus the 12 volt battery is all we see here...or the hybrid battery.

    Having been on this site for 10 years I can definitively recommend that you get a new 12 volt battery.
     
  9. dolj

    dolj Senior Member

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    These voltages indicate that the battery definitely needs to be charged. If the dealer is saying the battery is good, and hopefully they are correct, then this is all that is needed.
    This voltage seems a little low given the 12 V battery voltages you mentioned above. I would have expected it to be more in the realm of 14.0-14.4 V.
    Even with the lights going off there still chould still be at least DTCs in history or pending, if not current. You should ask your dealer what codes they saw and post them here. Possible, P0A08-254 (not to be confused with P0A80) and maybe the nefarious C1241.

    My suspicion is you are experiencing an intermittent inverter or DC/DC converter problem.

    I would be keen to know the outcome of this. Keep us updated and let us know you get on.
     
  10. edthefox5

    edthefox5 Senior Member

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    10.9 is done. The battery is probably hammering the dc dc converter. The car has been flashing a red exclamation point at you for probably quite a while on boot up.
    That means replace the battery.
     
  11. dolj

    dolj Senior Member

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    That is one explanation, but not the only one.
     
  12. Emmanuel Isaac

    Emmanuel Isaac Junior Member

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    Yes the first time the lights came on last year, I took it to the dealer to get it checked it out. They told me it had the C1241 code but upon further diagnosis of the other ECUs they did not find any errors. He said there was no problem and cleared out the codes.
     
  13. dolj

    dolj Senior Member

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    Probably of more relevance is what codes are there now. Even if it is still only the C1241, it is still relevant. It could go to show a pattern.
     
  14. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Here are my answers:
    1. You need to use a 4A battery charger, and charge up the battery overnight. See if that helps the battery voltage measurement.
    2 and 3. Look up the terms of the Toyota True Start battery warranty.
     
  15. Emmanuel Isaac

    Emmanuel Isaac Junior Member

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    So I went ahead and purchased a charger and connected it overnight. I had also taken a long trip about 5 hours a couple of days ago.

    I took readings at the battery prior to charging and to my surprise the voltmeter read 12.72v. The reading in the car's MFD was 11.7v at IG ON.

    After charging at 4A overnight the meter said it was full. Checked voltage at the battery and it now showed 12.69v on the voltmeter. The reading in the car's MFD is 11.8-11.9v at IG ON.

    I'm now wondering why the reading at the battery is different from what is showing up at the MFD. Is this normal? Or is there a ground leak somewhere?
     
  16. Prodigyplace

    Prodigyplace Senior Member

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    Make sure the connection between the negative battery terminal and the chassis is good.
     
  17. Emmanuel Isaac

    Emmanuel Isaac Junior Member

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    Okay so yesterday as I was heading home the ABS and Brake lights came on just as I exited the freeway and hit the brakes. As I knew this could be part of the same electrical drop issue from earlier I turned off the A/C and immediately the warning lights turned off.
    I got home safely and today I got the codes read. It was the C1241 again. I took a screenshot of the voltages for IG1, IG2, BS1, BS2, VM1, VM2, +B1, +B2 that are displayed in techstream and attached it for reference.

    I would like if someone here could help me figure out were I can find these live voltages in the software, as I'd like to see what they are when the error is not thrown. So far I am only able to find this info when the error is thrown through the Freeze Frame Data tab.
     

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  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Have you looked at the inverter coolant reservoir when the Prius is READY, to see if there is fluid turbulence which shows the inverter coolant pump is working?

    The voltage readings in the screenshot definitely are abnormally low.

    Also, check the battery cable connector tightness especially the negative cable where it bolts to the body.
     
  19. Emmanuel Isaac

    Emmanuel Isaac Junior Member

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    Yes there is turbulence in the inverter coolant reservoir and the battery voltage measures 12.86V after resting 24 hours and 14.03V when ready. In the MFD the signal check voltage shows 12.5-12.6v after resting and 13.8V in ready.

    I'm beginning to think its an issue with the Brake Assy Power Control Unit but wanted to know where I could check these voltages live in techstream so I can monitor it and see if there's any difference after replacing it. Does anyone happen to know where I can find the IG1 and IG2 voltages?
     
  20. dolj

    dolj Senior Member

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    The
    There is a difference between the the voltage reading on the MFD and when you measure at the battery terminal, just the same as if you measure at the 12 V plug in the centre console. It is not really significant that they are different, just accept that is the case.

    What matters now is just choose one methodology for measuring the voltage and stick to it. The easiest place to measure voltages is at the jump point in the fuse box under the hood. Connect your DVM up and place it so you can see the display from inside the car.

    I'm not convinced the 12 V battery is in good condition.

    To decide whether the 12 battery is good or not, you need to do this load test. With the car off, you need to measure the OCV (open circuit voltage). Make a note of it. Then, with the car still off, switch on the headlights on high beams. Observe the voltage and note how many seconds (or minutes) it take for the voltage to settle at a steady value and make a note of that. Measure how long it take to drop to 10.5 V and make of that time too. If your 12 V battery is not in a good state, you could be chasing your tail trying to diagnose this C1241

    Now to the C1241. The description of this code and also the related C1242 is:

    These codes are memorised when the power source voltage for the skid control ECU drops or the voltage for the ABS NO. 1, ABS NO. 2 relay operation drops.

    Codes may be memorised when the voltage of the auxiliary battery temporarily drops.

    When the power source voltage is too high, the skid control ECU stops functioning and outputs no DTCs, and the ABS and BRAKE warning light remain on.

    HINT:
    DTC C1256/56 (accumulator low voltage malfunction) may be memorized if the power source voltage drops.

    Your Techstream FFD data shows that you have a detail code 83. The repair manual says this about the C1241-83:

    DTC No. Detailed Code DTC Detection Condition Trouble Area
    1 C1241 83 Capacitor mode signal is received from brake control power supply for 3 sec. or more when READY is on.
    • Brake control power supply assembly
    • Brake control power supply
    • Hybrid control system


    This could indicate that something is drawing the 12 V bus down hence the capacitor mode signal.

    Also note the statement "Codes may be memorised when the voltage of the auxiliary battery temporarily drops." from the above DTC description for the C1241. If the 12 battery can be proved to be 100% good, then you will need to uncover why the 12 V auxiliary battery temporarily drops.

    I wouldn't be trying to diagnose this DTC unless you have proved the 12 V battery to be 100% good.
     
    #40 dolj, May 29, 2018
    Last edited: May 29, 2018
    Raytheeagle likes this.
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