Can someone tell me if these voltages are OK (12 Volt Battery)

Discussion in 'Prime Technical Discussion' started by schja01, Mar 3, 2019.

  1. schja01

    schja01 One of very few in Chicagoland

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    2018 PP Advanced 7 months old 1800 miles (18 hundred not 18 thousand).
    I probably don't need a second car but the "GeeWiz Factor" of the Prime was something I couldn't pass up.
    I got the infamous 12 volt Battery Low message yesterday. I recovered by putting my 1amp maintainer/charger on until it's indicator turned green. About 12 hours.
    Short of taking mostly short trips (2 to 3 miles each) I can't explain why the 12 volt battery ran down. I run mostly in EV mode but but a few miles each week in HV to keep the engine lubricated.
    So I went and purchased a digital VOM and a Voltage display gizmo that plugs into the Cigarette Lighter.
    The voltages taken at the 12 volt battery posts with the VOM were very close to those with the Cigarette Lighter device.
    Here is what I got. I wonder if specifically the IG ON voltages are good in that they are below 12 volts.
    I don't have any readings for when the car was in 12volt battery low status.
    Thanks in advance.
    Car OFF
    12.42 volts
    ACCESSORY
    12.07 volts
    IG ON
    11.74 volts Headlights ON
    11.84 volts Headlights OFF
    READY (EV Mode)

    14.28 volts Headlights ON
    14.44 volts Headlights OFF
     
  2. bisco

    bisco cookie crumbler

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    Everything looks normal except car off, which is low for a newer battery.

    You are experiencing the infamous prime 12v conundrum, which has yet to be solved.
    Have you read any of the threads?
     
  3. schja01

    schja01 One of very few in Chicagoland

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  4. schja01

    schja01 One of very few in Chicagoland

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    I never start a thread without searching PC and Google. That said, it’s sometimes difficult to formulate a search argument until you know the answer. Sort of a chicken and egg syndrome.
     
  5. bisco

    bisco cookie crumbler

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    the latest conclusion I've read is inconclusive. seems to be a bad batch of batteries, bad charging routine, or too much quiescent draw
     
  6. schja01

    schja01 One of very few in Chicagoland

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    FWIW now that I have a Digital Volt Ohm Milliammeter it dawned on me to check my Venza’s battery. It shows 12.34 volts with the car off. It’s colder outside where it’s parked compared to the attached garage the PP is in. The Venza’s battery was replaced in September. According to some battery web sites this is a somewhat low reading but not all that different than the Prime’s.
    I’m bringing the PP in tomorrow for it’s first post sale visit and have the ICS Service Campaign performed. The Service Rep will get a bit of an earful from me regarding the failure to start and 12 volt battery issues.
    Thanks,
    J
     
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  7. lextoy

    lextoy Active Member

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    car off measuring, at battery terminals preferred...
    you gotta pop the hood and come back the next morning to check it. after a drive, it will read artificially high, and after you open the drivers door, it reads artificially low for a while because opening that door wakes up the computers.
    my guess is you are not driving enough. thats not alot of miles at all. this car guaranteed has some parasitic drains on the battery even when off. all newer cars do.
    if that is a good charger/maintainer aka correct for car batteries, aka ok to leave on for a week or longer, then leave it on charge overnight, or for a few days/weeks. while you arent driving. try to top it off with extended charging.
    if not the right type of charger (and 1 amp is very small) get a better one. and try to get that resting voltage back to 12.6 or better.
    if you continue to drive so few miles, then stick the charger on once every 2 weeks to keep the 12V in better condition.
    also you could have just drawn it down by sitting in accessory mode, one time, or leaving a light on, one time, etc.
    also cold weather tends to make battery harder to charge and voltage drops over time as a result.
    combination of all this is why batteries die in the winter.
    yours seems to be ok at the moment after the recharge, but i would recharge for a few more days, and then keep an eye on it. monitor the voltage monthly, see if it drops back down to 12.4 or 12.2, which it shouldnt if you top it off regularly.
    would be interesting to know what the voltage was BEFORE you recharged it...
     
  8. lextoy

    lextoy Active Member

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    your PRIME is sitting as much as some peoples classics or exotics...they keep those on battery minders at all times !!
    i have a cadillac XLR it sits on the minder 24/7 and has had more than 1800 miles in the last 7 months...
    you could install a quick connect wire directly to the battery, and fish it through the grill or somewhere, so you could plug in the maintainer without opening the hood. they also make some that will plug into the cig lighter. but you gotta be sure the cig lighter stays hot all the time. welcome to the exotic car club maintenance world ; )
    XLRsunset.jpg
     
  9. schja01

    schja01 One of very few in Chicagoland

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    I brought the Prime in this AM primarily for the ICS Service Campaign and asked they look at the 12volt low problem.
    As expected nothing was found wrong with the battery etc.
    He did say they see this fairly often with cars driven infrequently eg. Corollas etc. and not limited to Hybrids.
    He offered the suggestion to put the Maintainer on once a week to keep the battery charged well.
    I'm going to watch the resting battery voltage closely now that I can and if it starts dropping off I'll follow his suggestion.
    upload_2019-3-4_9-10-37.png
     
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