Chosen Solution

Hi, hoping someone can give some advice. I’ve done a lot of research on battery / charging issues, but I just wanted a further opinion before I proceed as I’ve seen a lot of variance on these problems both in their issue and the fix. My Macbook Pro A1502, board 820-3476-A, has an odd issue that I’m not sure how to approach. This laptop was left with absolutely no charge in the battery for a time, and on returning to it, the magsafe went orange, and never came back on, and will not wake-up the device. I did manage to charge it by leaving the magsafe there until it started, but now it only charges to at most 49% before the charger supplies 0Watts. If I run it down low, the laptop will report a normal charge, until it approaches 49%, after which it drops to 0.1, and finally 0Watts. The laptop will then run off the battery without issue. It will also run with the magsafe attached, and will maintain the 49% charge until I begin using it on battery. All battery information from Coconut Battery (or equiv) reports normal operation. OSX battery indicator states “not charging”, however has lightning bolt symbol and does indeed charge. My question is: Could it be a calibration issue (the battery is 5years old) and the 49% is in fact the new 100%, and the laptop just isn’t aware of this? Could it be a magsafe DC board issue - the board is slightly corroded, and the magsafe adapter itself does not light up. Could it potentially be a component (J7000, U5000, U7100)? The main reason I ask is because I’ve seen conflicting advice, and if I re-calibrate the battery (letting it die completely etc) it might never come back on again. I’m also not hugely experienced with the specifics of what readings I should get from a multimeter should I need to do that with the board. Any advice would be appreciated.

OK, computer is now fixed and working. Magsafe DC-in was dead. If anyone has a similar issue, these are the steps I took (schematic naming convention may vary for you).

  1. Measure power rails to see if they are all present. If you have PP3V42 your ISL most likely isn’t dead.
  2. Green light / charging issues are most commonly caused in the current sense circuit. Firstly check U7100 for CHGR_ACIN (4v).
  3. Check to see if the ISL is talking to SMC - Pin 11 SMBUS_SMC_5.
  4. Check for SMC_BC_ACOK on a probe point (3.42v).
  5. Check to make sure U70001 has both SMC_BC_ACOK (3.42v) and PP3V42 power rail. Check your pullup resistor on U7000 (R7029).
  6. Check all your resistors in general - R7110, R7111, R7122, R7121 etc. If your issue is like mine however these will probably be OK.
  7. WHERE MY ISSUE WAS - Check your voltages on ADAPTER_SENSE and SYS_ONEWIRE. These should be 3.42v, mine measured at 1v. Issue was traced back to faulty magsafe DC board. For further help, check out Louis Rossmann’s YouTube series. Measure your rails and work backwards to find the problem. For current sense (i.e. battery not charging, no light) it’s going to be DC-in, the ISL (U7100), a resistor on the circuit, or if you’re really unlucky, the SMC. Oh, and don’t go ripping your battery out like the guy below suggests. Figure out the problem with your board first before you start making assumptions.

Lithium batteries suffer most when left drained for good. In such condition they deteriorate and might get swollen and die completely. Given you battery history, it would be reasonable to replace it before concerning about anything else.