X1202 not charging batteries

• D

  DR

  11/3/25, 3:11 PM

  Hi,

  My X1202 stopped charging the batteries. The battery indicator is always 4 bars on the LED. I checked the batteries invidually using a multimeter and they all have 4+ V, however battery volatage is always very low. Here is the output of vcgencmd pmic_read_adc
   3V7_WL_SW_A current(0)=0.10540040A
     3V3_SYS_A current(1)=0.06636324A
     1V8_SYS_A current(2)=0.18249890A
    DDR_VDD2_A current(3)=0.01073523A
    DDR_VDDQ_A current(4)=0.00000000A
     1V1_SYS_A current(5)=0.83442020A
      0V8_SW_A current(6)=0.34059960A
    VDD_CORE_A current(7)=1.35736000A
     3V3_DAC_A current(17)=0.00018315A
     3V3_ADC_A current(18)=0.00036630A
     0V8_AON_A current(16)=0.00439560A
        HDMI_A current(22)=0.01978020A
   3V7_WL_SW_V volt(8)=3.61347600V
     3V3_SYS_V volt(9)=3.31652900V
     1V8_SYS_V volt(10)=1.82124300V
    DDR_VDD2_V volt(11)=1.10622600V
    DDR_VDDQ_V volt(12)=0.60402870V
     1V1_SYS_V volt(13)=1.10036500V
      0V8_SW_V volt(14)=0.79706880V
    VDD_CORE_V volt(15)=0.71936430V
     3V3_DAC_V volt(20)=3.30127900V
     3V3_ADC_V volt(21)=3.29853100V
     0V8_AON_V volt(19)=0.79765500V
        HDMI_V volt(23)=4.99150000V
       EXT5V_V volt(24)=4.99820000V
        BATT_V volt(25)=0.00341880V

  When I try to read the status of the battery using python I get this error -"OSError: [Errno 121] Remote I/O error". Any thoughts on how I can debug this?

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• d

  dipakos

  12/23/25, 10:02 AM

  This almost always points to a hardware / communication issue, most commonly with I²C, SMBus, or SPI battery monitors.

  • I²C / SMBus (very common: fuel gauge ICs like MAX17043, BQ series)

  • ACPI / system battery unblocked games (laptops)

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• l

  lindasmile116

  12/29/25, 2:37 PM

  This is very likely a hardware issue in the battery path, not a software problem.

  Key signs:

  • BATT_V = 0.003V → the PMIC does not see the battery at all, even though each cell measures ~4V

  • Battery LED always shows 4 bars → stuck / false indication

  • Python error OSError: [Errno 121] Remote I/O error → the battery gauge IC is not responding on I2C

  Quick debugging steps:

  1. Check the battery connector, cable, and socket (very common failure point).

  2. Inspect the battery protection circuit / MOSFET / fuse on the X1202 board.

  3. Test with a known-good battery pack (the BMS may have tripped).

  4. If unchanged, the charger or fuel-gauge IC is likely damaged → board replacement needed.

  If the cells are OK but BATT_V ≈ 0V, it almost certainly indicates a hardware fault in the battery circuitry.

  
  Edited by lovemoney a day ago

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