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I have an early 2008 Macbook Pro (not sure on the exact model as I do not have it with me) which is having some interesting (annoying) power issues.

When the laptop runs flat and the machine turns off, I plug in the charger, and attempt to boot. Nothing. The machine will not turn on for roughly 30 mins, or until the battery is 20-25% charged.

Alternatively if I take out the battery and attempt to boot with the charger plugged in, but still no response.

I have recently purchased a new battery but the problem remains.

Any suggestions would be great!

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Are you using the charger that came with the laptop? Smaller 60W chargers from the 13" MPBs are not guaranteed to work with 15" MPBs (which require an 85W charger). –  Peter Gibson Nov 30 '10 at 5:26
    
Spot on! Thanks very much! –  JT.WK Nov 30 '10 at 8:28

2 Answers 2

up vote 5 down vote accepted

Power adapter

Are you using the same MagSafe power adapter that the system came with? The early 2008 MacBook Pro needs an 85W power adapter to work properly. If this isn't the original power adapter, check it to make sure it is 85W. Some MagSafe adapters, especially ones built for the MacBook Air, may not provide enough power. It is also possible that your power adapter has failed somehow. If your power adapter is 85W, try charging your computer with another power adapter.

Power Manager

The Power Manager in your notebook can cause strange power behavior like this, and it may need to be reset. To do this, disconnect the power cord, remove the battery, then hold the power button for at least 5 seconds. Then reinsert the battery and reconnect the power cord, and check whether the problem has been resolved.

PRAM

It is also possible that the PRAM has become corrupted or has bad settings, many of which you cannot access directly. You can reset the PRAM to its default settings without losing any data. To reset the PRAM:

  1. Make sure the computer is shut down and plugged in.
  2. Press the power button and immediately hold down the Command, Option, P, R keys simultaneously.
  3. Hold the keys until you hear the startup sound a second time.

Apple Hardware Test

If the problem persists, you can instruct your MacBook Pro to perform a full self test to try to determine the problem. To do this:

  1. Disconnect everything connected to your computer, leaving only the power adapter connected.
  2. If the computer is on, shut it down.
  3. Turn on the computer while holding the D key down.
  4. When the Apple Hardware Test chooser screen appears, release the D, then select your preferred language.
  5. Press the Return key or click the right arrow button.
  6. The Apple Hardware Test main screen should appear in about 45 seconds. When it does, follow the onscreen directions.

If the test detects a hardware problem, it will display an error code. If it displays an error code, write it down. Call Apple support or bring your computer to a Genius Bar, and tell them what error code you received, or search for the error code online.

If you cannot find the answer yourself

If none of the above steps solve your issue, the best thing to do is to call Apple or visit a Genius Bar.

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Thanks TuxRug. I'll try these tonight and report back! –  JT.WK Nov 30 '10 at 5:38
    
So, the charger that I use is from my girlfriend's Unibody 15.4". As it isn't a 13", I almost dismissed the smaller power charger issue without even checking. But, it turns out that the chargers is in fact a 60W! Not sure if this came with her machine, or it was accidentally swapped with a friend's. Either way I will try with the 85W just to make sure, but I'm fairly certain that this will solve the issue. Happiest man on earth! Thanks for your help! –  JT.WK Nov 30 '10 at 8:27
    
Yep - The smaller charger was definitely the problem! Thanks for your help! –  JT.WK Dec 1 '10 at 23:03

A few of the old Macbooks had the problem where if they were left running, the CPU would move out of the socket due to heat, so when it shut off, you had to wait for it to cool down before the machine would start working again. It's possible that you have a defect on your Logic Board, ergo you having to wait awhile before using your machine. I would recommend taking it to an Apple Authorized Service Provider so that they can run ASD. I would also recommend you bring your charger so that they can ensure that it is charging your battery properly and so that they can run the Battery Diagnostics.

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Cheers for the response Madison. A couple of things to note, if I put the laptop away for a couple of days after it runs flat, I still have to wait for it to charge up to ~20%. Secondly I use the same charger for another MBP which does not have the issue. I may take it into the Apple place and see what they can do for me. Thanks for the suggestion. –  JT.WK Nov 29 '10 at 21:03
    
I wonder if your CMOS battery is still good. Also, is the place where the battery actually connects to the machine(completes the circuit) clean or has any obstructions? –  Madison S Nov 29 '10 at 21:11

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