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Is it possible my car is reducing the charge in my cell?

  1. Apr 15, 2015 #1
    When I plug attempt to charge up my cell phone by plugging the cell phone charger in the cigarette outlet in my car, the cell phone charge icon will light up like it does when it is charging, but the charge on my battery will decrease fairly quickly at the same time. I suppose it's possible that my charge is just decreasing due to the power being on on my cell phone, but it sure appears to me like the battery's charge reduces much faster than when my cell phone is on but not plugged in.
    Is it possible that my car is actually decreasing thee charge on my cell phone's battery when I have my cell phone plugged in to my car's cigarette outlet?

    I don't think that this will help, but just in case, I will say that I have a 2012 Toyota Corolla.
  2. jcsd
  3. Apr 15, 2015 #2
    I reckon everything is OK here.
    Your phone says it is charging .. good.
    Your car battery says it providing additional charge to something .. good
  4. Apr 15, 2015 #3
    Why does the charge on my cell phone decrease rather than increase then?
  5. Apr 15, 2015 #4
    You mean it say's it is charging but in fact it does not charge?
    I would try and try to see if it charges normally from some other source.
    It could be the battery in your phone is breaking down.
    I doubt that the battery in your car is broken.
  6. Apr 15, 2015 #5
    The cell phone says it's charging, but not only is it not charging, the charge actually decreases rapidly.
    The cell phone charges normally from the electrical outlets in my house.
  7. Apr 15, 2015 #6
    Weird, well anyway if you can't charge it from the car battery then you can't.
    If it doesn't work then it doesn't.
    Either your phone battery is about to die, or your car battery is.
  8. Apr 15, 2015 #7


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    Long shot: It is possible that your phone is using a lot of its charge while in the car. If you have some features running, such as navigation, or other apps that update in the background, they could be having trouble communicating with cell towers inside what is essentially a radio signal insulator - especially true if the phone is resting near the radio. The poor signal may cause the phone to boost from a low power mode to a high power mode, draining its charge faster.
  9. Apr 15, 2015 #8


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    Staff: Mentor

    It's pretty common for cell phones to burn energy faster than they receive it from a charging cable, when they are active/the screen is on (mine does). Turn the screen off and let it sit idle for a few minutes and it should charge.

    Also, make sure you are using a 2 amp charging adapter, not a 1 amp adapter.
  10. Apr 17, 2015 #9


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    Is the car charger an oem charger, or a "compatible" charger.

    There are signalling protocols between phones and chargers to determine charger capacity. For example, a USB port will supply 100ma. If the phone connects to USB (data-wise) it can request 500ma. If a dedicated charger has D+ and D- shorted, then that indicates it can supply 1.5A. There are other protocols as well.

    Some phones will only charge correctly with certain chargers.

    It could be that the car charger is charging at a very low rate, and also the phone is keeping the screen on, so the charger can't keep up.

    By "car charger is charging at a low rate" I actually mean the the phone is deciding to only draw a small amount of current from the car charger because of what it thinks it is connected to.

    The other possibility is that the car charger is not functioning correctly. But it is unlikely that it is actually drawing battery power from the phone.

    I'll guess that if you connect the phone to a USB port on your computer you will see the same behavior. (but that's just a guess)
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