MacBook Pros suddenly shutting down when disconnected from power adapter (#2): Bad batteries
MacBook Pros suddenly shutting down when disconnected from power adapter (#2): Bad batteries
We continue to report on on an issue where the MacBook Pro suddenly and unexpectedly powers off when the unit is disconnected from external power while a battery charge remains.
When this failure occurs, systems generally refuse to operate from the battery. When they are powered on while disconnected from an external power source, they briefly begin to startup then power down immediately.
We previously noted that, for an in-house MacBook Pro experiencing this issue, the fix that eventually worked was resetting the PRAM with a twist. Apple indicates that resetting the MacBook Pro's PRAM requires holding down the Command, Option, P and R keys at startup until two restarts occur. However, we found that waiting for three or more startup chimes while resetting PRAM resolved this issue where waiting for only two chimes did not.
It now appears that, for some systems where the above workaround and another previously mentioned workaround, resetting the PMU, are not effective, a problematic battery may be at play.
Some readers have reported that after obtaining replacement batteries for MacBook Pros under warranty, the issue disappeared.
MacFixIt reader Mark writes:
"After talking to Apple about my MacBook Pro sudden shut down when disconnected from power adapter, I was simply ask about the serial number of the battery and few minutes later a free battery replacement was suggested."
Another reader, Simon Leemann writes:
"I just wanted to report that i have experienced similar issues with my MacBook Pro 2.0 GHz (manufactured week 12). Two weeks ago, the unit's battery time suddenly decreased rapidly while capacity went from 5800 to a mere ~3900. in addition the MacBook Pro would give the low battery warning and then suddenly shut off without going to sleep and without writing RAM contents to disk as you'd expect from safe sleep.
"I tried resetting the PMU and re-calibrated the battery but it didn't solve the issue. Finally, i called apple and asked them for a replacement battery. They wanted to know if i had already applied the firmware and SMC updates and if had tried resetting the pmu. When i mentioned that the battery's capacity had decreased by so much they agreed to send a replacement. The new battery just arrived yesterday. It's made in Japan and was manufactured in week 19. the original battery was made in China in week 12. now with the new battery everything seems fine and the capacity (after calibration) is at ~5600."
Finally, Joshua Ochs writes:
"After two months, mine started shutting off at 20% or so remaining - I took it to the Apple store and left with a new battery. No problems since."
Feedback? Late-breakers@macfixit.com.
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