Released October 2008 / 2.4, 2.53, 2.66, 2.8 or 2.93 GHz Core 2 Duo Processor

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MBP will not run on battery power

Late 2008 15" MBP Unibody 2.53 Core Duo

Upgraded to 8GB RAM

Running 10.8.2

My MPB shuts down immediately if I remove it from AC power, even though I have a fully charged battery. No Water, drop or squeeze damage. Coconut Battery and OSX System Profiler both state that the battery is Normal, 100% charged at 176 cycles. Coconut says the battery is 84% capacity, which i think is normal for its age.

A few other things of note:

1) The battery charge indicator button does not respond at all when I'm off AC power. When I plug into AC power, the battery indicator light works perfectly, showing that the battery is fully charged.

2) My fans are firing up at very odd times, such as start up. The MBP has been running hot since I installed Mt. Lion. Apple says this is not related to Mt. Lion.

3) RIght before this AC/battery issue started, I noticed that my battery was only lasting One Hour (!) off of a full charge. I could have sworn it was at least two hours life since I switched to Mt. Lion. The battery useage problem seems to have cropped up with the latest Mt. Lion update.

4) I did upgrade my MPB to 8GB of RAM. Apple doesn't officially support it for this model, but multiple users reported it's fine to do from Lion, upwards. I've attributed my extra fan activity to the 8GB Ram upgrade, which could be wrong :)

5) this is not a charger issue, same behavior on two other chargers.

6) I don't have access to a diff battery, as it's New Years Day & our Mac Repair store isn't open. If I can get access to another battery for testing I will update this post.

Many thanks for any help or advice!

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1 Answer

Chosen Solution

Give SMC reset a try here first: Apple TN on SMC Reset

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Aloha Dan,

I just redid the SMC reset. Sleep was ok, but possibly odd that I was not prompted for my password. Otherwise OK. Restart and Full shut down were fine too (as long as I was plugged into AC of course).

Then it got scary. MPB started up, green light on AC charger. Got to the grey apple screen, completely shut off. no green light on magsafe charger, nothing. Try again, Same thing. On the third try, it did start up. Holy smokes I need to go change my shorts.

My dad just reminded me that the magsafe indicator light malfunctioned a few times these last two days. It would be lit, then turn off, but OSX showed still charging. If i unplugged/replugged at the MPB the magsafe light would come back on, indicating the level of charge correctly (amber or green). I figured it was schmootz in the magnetic area, but now thinking it's another symptom of my mystery issue.


Well I was hoping i was just a messed up SMC.

Do make an effort to clean the contacts on both the charger & system with some isopropyl (if you think they are dirty).

Starting to sound like the power transistors which control the DC feed from the charger Vs the Battery are having problems. Sorry to say this model has them on the main logic board Vs the DC-in board.


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Erin will be eternally grateful.
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