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wjlafrance
Jun 28, 2010, 10:16 PM
Hey folks. I just bought a PowerBook G4 off of craigslist today. 1.67GHz G4 processor, 15" screen, etc etc. The battery shows 99%, and when I unplug it I can count one Mississippi, two Mississippi, three Mississippi, four.. oops, it's dead. In the menu bar I can see it recognizing that it's switched to battery a split second before the screen goes black.

An excerpt from System Profiler, leading me to believe the battery is fine:
Battery Installed: Yes
First low level warning: No
Full Charge Capacity (mWh): 3615
Remaining Capacity (mWh): 3587
Amperage (mA): 0
Voltage (mV): 12494
Cycle Count: 274

Any ideas?



DesmoPilot
Jun 28, 2010, 11:04 PM
Wow, it's even under the 300 cycle count for warranty's. Have no idea what could be wrong, tried the Apple hardware test?

flopticalcube
Jun 28, 2010, 11:08 PM
Reset the PMU (http://support.apple.com/kb/ht1431)?

The Power Manager is an integrated circuit (computer chip) that is usually on the logic board of the PowerBook and iBook. As the name implies, it is responsible for power management of the computer. It controls backlighting, hard disk spin down, sleep and wake, some charging aspects, trackpad control, and some input/output as it relates to the computer sleeping.

Over time, the settings in the Power Manager may become unusable, which can result in operational anomalies with the computer. Examples include not turning on, not waking from sleep, not charging the battery, or not seeing the AC Adapter, among others.

iThinkergoiMac
Jun 28, 2010, 11:10 PM
Replace the battery and you'll be set, it's just a dead battery. I know system profiler tells you it's fine but it's just a bad battery.

wjlafrance
Jun 28, 2010, 11:15 PM
Reset the PMU (http://support.apple.com/kb/ht1431)?

First thing I tried. I also tried reset-nvram, set-defaults, reset-all to no avail, followed by a triple PRAM reset. No dice.

I'll ask one of my instructors who's an Apple fanatic if he happens to have a spare battery laying around.

wjlafrance
Jun 29, 2010, 02:43 AM
When I restarted, it had rolled the time back to the epoch, even after I previously set it to today. I believe this indicates a dead PRAM battery? I don't have much experience with PRAM, but I know that when a CMOS battery dies, you can kiss your PC working as expected goodbye until it's replaced.

Does this sound reasonable? The previous owner said this was happening before he bought the new battery (although that doesn't explain how he cycled it 274 times, maybe he bought it used?). I figure it's worth the $5 to try it.

EDIT -
I'm giving it the Apple suggested four hours of running off the power supply without a battery installed, since the PRAM battery is apparently rechargeable. Meanwhile installing Leopard combo upgrade. I really hope the logic board isn't a lemon. Backlit keyboards aren't cool on desktops.

Hrududu
Jun 29, 2010, 08:20 AM
Sounds like one of the cells in the Battery is dead. When the Mac tried to pull power from it, it thinks the battery is dead. I've got a battery in my 12" Powerbook that is similar to that one. It'll last for about 45 min or so, but as soon as it hits about 68% remaining, it goes to sleep and won't come on again until I attach power. When I plug it, it shows the battery discharged.

zen.state
Jun 29, 2010, 10:58 AM
I would guess dead cell also. If so it would be about a $100 fix.

wjlafrance
Jun 29, 2010, 03:53 PM
I left it running over night to recharge the PRAM battery and no dice, so I'm guessing that needs to be replaced. What's really interesting is that if I close the lid and unplug the power cable, then plug it back in somewhere else, it'll awake from sleep but has forgotten the system time and my wifi network, leading me to believe that main power may be fine but the PRAM is just shot.. but then main power should be holding the PRAM for me.

I can't afford a new battery right now, so I'm just going to get a new PRAM battery and see where we go from there. Anyone have a guide for cracking an AlBook open?

666sheep
Jun 29, 2010, 04:19 PM
http://www.ifixit.com/Guide/Repair/Installing-PowerBook-G4-Aluminum-15-Inch-1-67-GHz-PRAM-Battery/635/1

kbfr08
Jun 29, 2010, 09:23 PM
If you feel comfortable doing so, you can disassemble the battery and replace the cells. It's an easy job, I did it to my macbook.

Your battery probably has a dead cell, you can actually see an air bubble in the Li-Ion cell if it has gone bad. The cells should not have any air in them unless they're dead.

To replace a cell, cut the wires for + and - and dispose of the battery properly. Find a similar mAh and Voltage battery on ebay, then solder it into place making note of the polarity. I think you need 6 cells for the battery, you could try only replacing the dead cells though. Individual cells cost about $7 each on eBay depending on the seller.

wjlafrance
Jun 30, 2010, 02:52 AM
If you feel comfortable doing so, you can disassemble the battery and replace the cells. It's an easy job, I did it to my macbook.

Your battery probably has a dead cell, you can actually see an air bubble in the Li-Ion cell if it has gone bad. The cells should not have any air in them unless they're dead.

To replace a cell, cut the wires for + and - and dispose of the battery properly. Find a similar mAh and Voltage battery on ebay, then solder it into place making note of the polarity. I think you need 6 cells for the battery, you could try only replacing the dead cells though. Individual cells cost about $7 each on eBay depending on the seller.

Although I love being able to tell stories about potentially killing myself, I'll pass this time. I found a few on ebay for around $30.

wjlafrance
Jun 30, 2010, 11:51 PM
Just as mysterious as the problem itself, I tried starting the computer today with it unplugged (I've been doing this every so often, with a teaspoon of wishful thinking) and it started up just fine. The battery is at 62% and falling, and I'm getting great battery life.

If I had to speculate, I'd say something inside the computer was extremely discharged and took forever to recharge.. or something like that.

EDIT -
The issue is back. An Apple Genius basically told me "Yeah, when a logic board is failing, it'll work sometimes and not other times."

The computer has been admitted to the Macintosh nursing home, also known as eBay. Someone else's problem. (I stated that it doesn't run off the battery)