1. AC Question's Avatar
    Hello, I am trying to run my tablet, LG VK815, without a battery. The reason for this is cause the main board can not charge batteries. I have connected 4.2V 2A adapter power to a battery connector while putting a thermistor at the supplied power. I could boot up the tablet but it goes down so quickly. I can see Verizon message. Does tablet checks volts? 4.2V too high? Or I have checked the voltage after thermister to be around 3.2V. Is a thermistor making a trouble? Please help me to fix this problem.
    10-05-2016 12:41 PM
  2. Rukbat's Avatar
    4.2 Volts externally? MUCH too low, it requires 5 volts. 4.2 volts at the battery terminals (with the battery disconnected)? It should work, but the voltage should be about 3.8 Volts. With the battery connected? Not unless the battery is charged. Thermistor? There shouldn't be any.
    10-05-2016 03:22 PM
  3. jhpark3's Avatar
    Sorry, it seems my writing was not clear. My tablet now does not have any batteries. Instead, I have provided a power to my internal battery socket faking I have a battery. In order to fake a battery, I need a thermistor because main board checks temperature.
    10-05-2016 08:05 PM
  4. Mooserman15's Avatar
    Can you post a schematic of what you did? Where is your thermistor? If you put the thermistor in series with the power supply, WRONG! If you put the thermistor between T and GND on the tablet board, CORRECT! Your power supply should be able to output 3.8-4.2 volts with load. Also, is the 2 amp rating running or peak?
    10-05-2016 11:10 PM
  5. jhpark3's Avatar
    I have three cheap testers. Two of them cannot measure 2A. The other one looks broken because the number changes continuously.
    According to my measure, it seems one analog tester 4.0 <= Volt ranges <= 4.2 . Another digital tester's results are 3.95V <= Digital testers <= 4.3 .It seems runnung volts are around 4.0 ~ 4.1 . I could not measure running Ampheres.
    10-06-2016 08:34 AM
  6. jhpark3's Avatar
    My thermistor connection looks OK. I will post Amphere data when I get a better tester. Thanks for your replies.
    10-06-2016 08:58 AM
  7. Rukbat's Avatar
    If the number keeps changing, either it's meaningless (and we can't use it to diagnose anything), or you're drawing a lot more out of the charger than it can supply - in which case the tablet won't work.
    10-06-2016 12:04 PM

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