MacBook Pro shuts down when starting up from battery
I have a MacBook pro from 2009 (2,8 GHz Intel Core 2 Duo, 8 GB 1067 MHz DDR3, Crucial MX500 SSD, NVIDIA GeForce 9600M GT 512 MB).
Many times when starting up from battery the system shuts down prematurely unless the battery is fully charged. When the battery is not fully charged this happens even when the charger is plugged . But when the battery is fully charged it never happens.
I have replaced the battery with a new one but this problem still exists.
I have done SMC and NVRAM reset but it didn’t help. I see some other people reported the same issue but no one could figure out the issue. I did AHT test and it didn’t detect any hardware issues.
Can somebody tell me why this is happening?
MacBook Pro 17″