I have the same problem, but with a MacBook Pro8,1 Early 2011
I replaced the already dead swollen battery for a new one from a seller in Amazon, it came with 78% charge, but it won't charge, I already troubleshoot for bad AC cords, which they work fine with other MacBooks, without any luck, tried resetting the SMC, force shutdown, disconnect battery and press the power button while no battery present, checked physically if the battery was not connected properly, so far nothing has worked, I even run Terminal with the next info:
-g batt
Now drawing from 'AC Power'
-InternalBattery-0 (id=4915299) 42%; AC attached; not charging present: true
Do you have any other suggestion that might help?
On the other hand, vents are always on a medium to high level with only one app run
[image|3095049]
[image|3095052]
ning, I also replaced RAM and upgrade to a SSD. Could any of these changes affect the battery charging?