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820-2915 Charging slow

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  • 820-2915 Charging slow

    MacBook came in with a swollen battery a few months ago and not holding a charge. Replaced battery and sent customer on their way. Customer comes back a 2 months later with the replacement battery no longer holding a charge and only had 1 cycle count. Considered it a defective battery and replaced under warranty. Customer comes back in again with the same issue of the battery not holding a charge, stuck a 1 cycle count.

    Ran coconut battery and discovered that the MacBook was charging that battery at 0.1 Watt. Discharging with 6.8 Watts

    On U7000
    PP5V1_CHGR_VDD= 5V
    PP5V1_CHGR_VDDP= 4.9V
    Resistant between pin 27/28 : 20.5 ohms
    Resistance between pin 17/18 : 2.8 ohms

    I replaced Q7055.

    MacBook now begins to charge at 15 Watts, but then drops to charging at 6.8 Watts

    Measured
    R7050 : 0.3 ohms
    R5441 on SMC_DCIN_ISENSE : 4.5k ohms
    R5420 on CHGR_BMON : 0 ohms
    R5422 on SMC_BMON_ISENSE : 45.3k ohms
    These reported normally.

    Replaced Q7055 again to rule out defective mosfet. No change.

    I then measured around Q7080
    R7085, R7086, R7080, R7081 were all reporting the same measurements when compared to a working board.

    I replaced Q7080.

    MacBook is still charging at 6.8 Watts.

    Just to make sure that the SMC was not screwing with the charging, I replaced SMC from a working donor.

    Still charging at 6.8 Watts.

    What I have determined is that something is limiting the charging current to the battery because the board will begin to take 15 Watts but then drop to 6.8 Watts. I installed another battery just to make sure that I don't have a defective battery only to have to same results.

    I know it is in my face, but what else is responsible for battery current sensing?


  • #2
    Did you try known good working battery???
    New chinese batteries are nightmare.
    Find an old original battery, just for test...

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    • #3
      I just tried 4 other batteries all from the same vendor and they were reporting different charging values from 6.2 watts to 9.8 watts. Being that the main parts of the board look perfectly fine leads me to believe I got a really bad batch of batteries.

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      • #4
        Just installed a used battery and now getting 22 watts. Being that I had multiple batteries report a similar reading, I assumed the issue was with the board. But it turns out that the issue was all around a bad batch of New batteries. Thank you.

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