1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Battery problems in neutral

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by alanwagen, Jul 2, 2011.

  1. alanwagen

    alanwagen Member

    Joined:
    Dec 15, 2008
    121
    79
    0
    Location:
    FORT WORTH
    Vehicle:
    2018 Prius
    Model:
    Three
    We went to the car wash, the kind that you put the gear shift in to neutral and the car wash pulls you through. So at the end, we receive a message with the warning triangle to put the car in park to charge the battery. We were wondering if our traction battery is dying. We just came from a 40 mile trip and the battery indicated that it was charged.

    It is a 2009 with about 42k miles.
     
  2. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,123
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    The HV battery cannot charge when in neutral so it's best not to leave it in that position for too long. If you have the AC on, that really drains the HV battery quickly. Make sure you shut off your AC first before going thru.

    It can charge via regen or the ICE in all other positions, including Park.
     
  3. firepa63

    firepa63 Former Prius Owner

    Joined:
    Jul 23, 2005
    1,761
    208
    0
    Vehicle:
    Other Hybrid
    Model:
    N/A
    It may have been the 12v battery. If you had your lights on and AC while going through the car wash, you may have dropped the 12v bus voltage low enough to trigger the error code.
     
  4. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,123
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    Seems unlikely. I don't think (but can check later) that the 12 volt battery bus voltage drops when you shift to neutral while in Ready mode. It should remain at 13.x to 14.x volts and continue to be charged/powered by the inverter.
     
  5. Rae Vynn

    Rae Vynn Artist In Residence

    Joined:
    May 21, 2007
    6,038
    707
    0
    Location:
    Tumwater, WA USA
    Vehicle:
    2007 Prius
    Model:
    Two
    I always check the SOC before deciding to use AC in the carwash... if it's green, I go for it.
     
  6. BAllanJ

    BAllanJ Active Member

    Joined:
    Dec 9, 2008
    667
    78
    0
    Location:
    Kingston Ontario
    Vehicle:
    2017 Prius
    Model:
    Two
    If you're waiting in line to get into the car wash and you're waiting with the ac on, then your battery will get low. Check that, and if it's low and your turn is near, then force charge by putting the car in drive, hold the brake on firmly and push the go pedal until the engine starts... hold until the battery has enough in it.
     
    1 person likes this.
  7. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
    3,318
    1,103
    0
    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    Lot's of info on this problem throughout the forum. I too ran into that problem shortly after my wife got her Prius which I take care of for her.

    After doing research here in PC and experiment's on my own, I found this helps me the most.

    If you must go through a car wash with a track and the car MUST be in neutral, hit the climate button on the MFD, then make sure the "Auto" button is off. If it is underlined, then it is on. Simply turn off the "Auto", then manually adjust the fan speed to a lower setting, close to the bottom ie: low or the first speed to the right hand side next to low. As long as you have at least 5 blue bars, you should be Ok and comfortable until you can get through the wash. Once you exit the car wash, then turn the "Auto" back on. The fan speed will resume it's normal operation.

    As other's have stated, the A/C does pull the HV battery down quickly. Once the battery is down to the lower end, under 20% charge, the master alarm will sound, red triangle of death will appear, and a message on the MFD will say "Put the car in Park to charge the battery". That is hard to do when you are being pulled along by a conveyer belt.

    The problem that causes this is the fact that the Prius WILL NOT charge the HV battery when the N is selected. The only other suggestion is this. If you must use a automatic car wash, use a "Laser Wash". With those units, you can sit in the car with the gear selector in P. Then if the battery does discharge while you are using the A/C, the ICE will kick on and recharge it until it reaches a point where there is enough to tell the system to shut down the ICE.

    I do note that one other poster here on PC suggested to slip the car into D which will start the ICE, and lightly hold the brake so the car will still move along with the roller on the conveyer. As I recall that same poster said the car wash attendant will not be very happy with you if you were to do that. To sum it up, make sure you have a good charge before you enter the wash, and try to eliminate the discharge as much as possible while you are in "N".

    Yes, it seems redundant that the Prius being such a smart car as it is that it will not charge the H/V battery when the gear selector is in N, but that is the nature of the machine. All cars are different, and the Prius is no exception. :)

    One last point to consider. The HV Battery is cooled by a fan as well as the A/C system in the car, so if you live in a hot environment like Texas, Florida, and so forth keep this in mind when you are operating your Prius. You could damage the battery if it was to get too hot.

    Hope this info helps everyone.
     
    Classic Car Guy, BAllanJ and Rae Vynn like this.
  8. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    55,270
    38,571
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    The Prius is the first car we've ever had that can't be shut off and in neutral.
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,200
    6,467
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Probably the first car you've owned that doesn't have a real transmission, either...
     
    Classic Car Guy likes this.
  10. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    55,270
    38,571
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Most of our previous cars were traditional automatics, with the exception of our previous HCHII with it's CVT.

    I don't know much about our Prius' transmission, just that it's almost like a manual, very simple, and the "gearing" is governed by computers working with the 2 electric components in it.

    So maybe one of the trade-offs is that Neutral is just not feasible with engine off?

    I did watch a very informative video online about the Prius transmission, linked by someone here. I don't know why, but try as I might I kept nodding off while watching it. Worse than the New Yankee Workshop, my other sleep-aid, LOL.
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,200
    6,467
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Neutral is normally not feasible when the car is IG-OFF (this has nothing to do with whether the engine is running or not.)

    The reason for this is because the various shift positions are not based upon mechanical components being arranged in a certain way, but rather are based upon an electrical state. Therefore, if the car has no power (i.e., IG-OFF) then the electrical state will not be retained.

    Neutral basically means that the motor generators are not electrically connected, which allows the axle shafts to freely rotate.

    Drive means that, under low speed stealth mode, MG2 is rotating the axleshafts. MG2 speed is always directly related to axleshaft speed.

    When the engine is running, MG1 is also rotating in a direction that allows the engine to run as well as enabling MG2 to spin at an appropriate rate, given vehicle speed.

    Prior to the car becoming IG-OFF, the parking pawl will be engaged, whether or not you press P prior to pressing the POWER button. Hence, the car cannot be moved when IG-OFF, unless you drag it so that the front tires slip, or raise up the front axle.

    One way to engage N when the car is IG-OFF is to put the car in N when IG-ON. Then remove the PCON relay (which provides power to the parking pawl.) When the car is made IG-OFF, it will remain in N and can be rolled around.

    However this is too much trouble for the casual owner who is going through a carwash.
     
  12. Gary in NY

    Gary in NY Member

    Joined:
    Jul 18, 2009
    153
    20
    0
    Location:
    Poughkeepsie NY
    Vehicle:
    2010 Prius
    Model:
    III
    As you can tell, there's not a technical reason why the car could not be powered off (IG-OFF) with the parking pawl disengaged. Toyota has obviously decided to be helpful and prevent driver error by automatically engaging park even if you don't press P before powering off.

    We could use a way around this for cases like the car wash or service. For example if the shift lever were held to N while powering off, park would not be engaged (then the display could warn that the car remains in N, not P , and the driver given a suggestion to press P if they really want Park). Unfortunately Toyota apparently hasn't considered this case., or chose not to make it possible. Good suggestion though on the PCON relay, but as you note, that's too much trouble for the car wash.
     
  13. Classic Car Guy

    Classic Car Guy Active Member

    Joined:
    Dec 23, 2018
    396
    114
    0
    Location:
    Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    II
    I have a question for my 2007 prius. Whenever I have the car on a long stop lets say on a drive thru station sitting for more than 12 minutes, the battery bar goes down to the last 'purple bar' then it charges. I'm not quite sure if its suppose to go down that fast for I cant even sit on the car longer than a normal gas engine car. I am struggling more or worried while waiting inside the car on a hot summer day that I'm force to run the ac even in the lowest fan position on 68 deg setting 'manually.'
    Do you think there is something wrong with the hybrid battery? If so.. what do you suggest?
    or
    if that is normal, is there any suggestion that I can change my battery pack to a much higher reserve capacity so I can at least survive on a good 35 minute wait inside the car with ac on rather than driving around to cool down and charge the the car at the same time.
    By the way the car is 150k miles and its well kept and driven normally. hybrid battery is original.
    Thank you!
     
  14. alanwagen

    alanwagen Member

    Joined:
    Dec 15, 2008
    121
    79
    0
    Location:
    FORT WORTH
    Vehicle:
    2018 Prius
    Model:
    Three
    I don't think that is normal either.
    If you go to a auto supply, they can pull codes for free. I've done before, they don't mind.
    But it is not only the miles that takes a toll on your battery, it is also time. 16 years is a long time for a battery.
     
  15. douglasjre

    douglasjre Senior Member

    Joined:
    Sep 13, 2008
    1,836
    640
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    He vacuum your car before going through so your battery is at two bars and then you go in and you put your car in neutral. This is how you destroy a battery
     
  16. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,859
    4,639
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    This is normal behavior. As the hv battery gets weaker it will discharge faster. Mpg will get worse.

    A sure sign of end of life is when you can't wait at a traffic light without the engine engaging to charge the battery. Sometimes if it is drained and you start moving, the power is noticeably less because the hv battery is not helping.

    The thing to do is get ready to buy new cells, preferably Toyota. Not refurbished. You will notice the difference and mpg will improve.

    With a new hv battery you could sleep in your car all night with the ac on. The engine will startup often but power to drive off normally will always be there. Discharge times at McDonalds will be longer. 35 minutes with ac? No.
     
    #16 rjparker, Jul 31, 2023
    Last edited: Jul 31, 2023