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Question: 2009 MBP won't boot unless power adapter is connected


I found a similar question in the forum from a couple years back but there were no solutions offered. I think this is an uncommon problem and am posting in case any here have encountered it before.

It's an early 2009 17" MBP (5.2) and the battery was replaced about 3 years ago to try addressing this problem. It's currently running El Capitan.

The computer will instantly power off just after the appearance of the Apple logo if booting without the power adapter connected. A couple times the progress bar made it half way. Apple menu -> Restart will sometimes successfully restart, about 1 out of 5 attempts. The success rate may be a little higher if I boot in safe mode but I wasn't keeping a count, it just seemed that way.

The computer often won't wake from sleep either. The sleep light is blinking, open the shell and tap a key to wake and the computer just dies. I can turn the computer on with the power cable attached, disconnect it and then run out the battery with out any troubles.

Coconut Battery reports the battery to have 17 cycles and 13100mAh capacity. I drained / charged the battery a few times over the past couple days using a webgl sample and 'yes > /dev/null &' to tax the CPU. The computer would run for about 3 hours before shutting off. Each time I did this I reset the SMC as per the Apple support docs (disconnect the battery, etc.). I would them fully recharge the battery (~5 hours??) before booting.

Any ideas what this could be? A flakey battery - but the problem started with the original battery and persisted with the new one; intermittent logic board problem or perhaps even a firmware issue that's affecting some power management setting?

I appreciate any suggestions people may have. Thanks!


MacBook Pro, OS X El Capitan (10.11.6), MBP5.2 - Early 2009, 17"

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Mar 5, 2018 3:17 PM in response to _jayryan In response to _jayryan

A little addendum...

I've been trying to boot in verbose mode to see if I can catch an error message and it's all over the place. Interestingly, Out of about a dozen boots into verbose mode 2 booted normally into the desktop.

For the rest, about half finished the cli output, went to the progress bar, and then the computer shut down at some point in the progress bar. The other half just booted a few seconds into the sequence where it started to print PCI info then shut down.


Mar 5, 2018 3:17 PM

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Apr 10, 2018 8:18 AM in response to _jayryan In response to _jayryan

I have this same problem.

MacBook Pro 5,2 (17-inch unibody, early 2009; 2.93 GHz processor). Upgraded to 8GB RAM & 7,200rpm 1TB hard disk drive.

Currently on the third battery, if memory serves.

I never had problems with booting prior to updating to El Capitan. Now, on El Capitan, it won't boot unless connected to AC electrical outlet, even if the battery shows a full charge. And even when connected to AC outlet, it usually needs to be allowed to sit plugged in and allowed to "warm up" for several minutes before I start attempting to boot, or it will almost certainly fail to boot.

I use FileVault to encrypt the whole drive, so there are two steps in the boot process. After pressing the boot button, there is a pause while the screen boots to the Apple logo. Then the password field appears, and after the password is entered, the decryption occurs.

The boot can fail at either stage.

Even when the MBP is connected to an AC outlet, if it is not allowed to sit and "warm up" for several minutes before pressing the boot button, it will almost certainly fail to boot to the Apple logo; it will just turn off, usually with a loud click sound. If it does make it to the Apple logo and accept the password, more than half of the time the boot will fail about 1/3 of the way into the decryption process, and the computer will just shut off. (This usually occurs around 30%-40% into the decryption, but there have been occasional times that the progress bar has made it as far as 80% of the way across before the process fails.) If I allow the MBP to sit plugged in to AC for several minutes before attempting to boot, and then to sit another several minutes after getting to the Apple logo but before entering the password, it seems to have the best shot at booting through completely to the desktop without failing (but even then, it's not a 100% guaranteed sequence).

It isn't 100% mandatory that the MBP be connected to AC power to boot, however. During a power outage, I was able to eventually boot it off the battery alone, but it probably took three-dozen tries.

Among the possible causes of the boot problems, I have considered:

- The upgraded RAM and/or hard drive causing a greater power drain at boot up than the MBP was designed for

- Some glitch in the FileVault decryption process (but that wouldn't explain why the first stage of booting, before the password is entered, fails on battery)

- Faulty battery

While I can't completely rule out the possibility of a faulty battery, I did try 3 different new batteries, and the boot problems occurred with all 3.

At this point, I don't think any of these possibilities is the cause (although I don't know).

Once it does make it to desktop, it runs absolutely fine until shutdown.

Apr 10, 2018 8:18 AM

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Question: 2009 MBP won't boot unless power adapter is connected