Reviving a "dead" phone?

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  • mammynun

    Master
    Rating - 100%
    10   0   0
    Oct 30, 2009
    3,380
    63
    New Albany
    I have two LG 920 Spectrums that I would like to use as ballistic calcs, GPS, camera, etc... basically everything that doesn't involve Verizon.

    Both batteries are fully discharged (I metered them), but will not charge... at least while they're in the device. Neither phone will boot with either the OEM charger or a 2 amp charger attached with the battery in or out of the device. I tried holding the both up and down volume controls and then plugging in the charger; no joy. These phones have SIM cards and microSD cards and I tried booting w/o the sim card, which didn't work. Both phones were working when they were replaced, and they've just sat in a drawer since.

    If y'all can't help me, I guess I'll have to find a geeky teenager....
     

    indiucky

    Grandmaster
    Rating - 100%
    12   0   0
    Where you been? I got a smartphone now and need you to download the cool stuff...Plus my wife has your wife's Christmas present down here and it's making the shop look girly...Well that and the sundress I am wearing today...(I didn't realize how "breezy" sundresses are at 15 degrees...):):
     

    K_W

    Grandmaster
    Rating - 100%
    8   0   0
    Aug 14, 2008
    5,385
    63
    Indy / Carmel
    I have two LG 920 Spectrums that I would like to use as ballistic calcs, GPS, camera, etc... basically everything that doesn't involve Verizon.

    Both batteries are fully discharged (I metered them), but will not charge... at least while they're in the device. Neither phone will boot with either the OEM charger or a 2 amp charger attached with the battery in or out of the device. I tried holding the both up and down volume controls and then plugging in the charger; no joy. These phones have SIM cards and microSD cards and I tried booting w/o the sim card, which didn't work. Both phones were working when they were replaced, and they've just sat in a drawer since.

    If y'all can't help me, I guess I'll have to find a geeky teenager....

    Buy a $10 prepaid Android smart phone at the drug store, you do not have to activate them to use camera, apps, GPS sensors, ect.
     

    mammynun

    Master
    Rating - 100%
    10   0   0
    Oct 30, 2009
    3,380
    63
    New Albany
    Where you been? I got a smartphone now and need you to download the cool stuff...Plus my wife has your wife's Christmas present down here and it's making the shop look girly...Well that and the sundress I am wearing today...(I didn't realize how "breezy" sundresses are at 15 degrees...):):

    I can fix that... but the non-cis transgender thing makes me want a safe space. See ya in a few...
     

    indyjoe

    Master
    Rating - 100%
    8   0   0
    May 20, 2008
    4,584
    36
    Indy - South
    Charge them for a while. (Hours)

    Lithium charging circuits have a few modes. Typical is constant current charge to a certain voltage, then constant voltage until the current drops to about 10% of the constant current level. If you have a voltage far under as certain value, it does an essential trickle charge to get the voltage up to a level that is safe to start the constant current.

    Typical lithium cells for tablets and cell phones will be at 50% capacity in 18 months. If these are years and years old, the batteries could be gone. If they have something left, they may need to be trickled for quite a while until they really start charging fast.

    It varies between systems if they can run exclusively on charger or if the need a little battery voltage, then pull most current from the charger. (Power Path charger or not)

    The tablet I designed and produce for work is a non-power path design. So it will charge the cell at 1.7A. If the tablet is running, then the charging current will be 1.7A minus whatever the tablet is pulling. But in a situation of total discharge, the tablet will not turn on until the trickle mode of charging is over and we are into full current charging. I believe that is what you have occuring here.

    It is also possible that the battery design protection circuitry is poorly designed and the disconnect MOSFET is powered by battery voltage. If there isn't enough internal voltage to power the gate on the transistor, it will be like the path to the battery is open and nothing will charge. I've seen this on early battery designs that we were given and I required a redesign.

    If trickle charging for a few hours doesn't fix the issue, you can purchase one new battery and see if it fixes the issue. If the batteries are fairly old, you are probably going to want to do this anyway.
     

    littletommy

    Grandmaster
    Rating - 0%
    0   0   0
    Aug 29, 2009
    13,015
    113
    A holler in Kentucky
    Where you been? I got a smartphone now and need you to download the cool stuff...Plus my wife has your wife's Christmas present down here and it's making the shop look girly...Well that and the sundress I am wearing today...(I didn't realize how "breezy" sundresses are at 15 degrees...):):
    I was just telling somebody the other day that you were one of the few people I knew that didn't have a smart phone. What is the world coming to?????
     
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