View Full Version : Strange PowerBook battery behaviour?

02-25-2005, 02:22 PM
When I run my 17" G4 PowerBook on battery, the capacity slowly decreases to 50 % or so. But then, in the space of a few minutes, itís suddenly empty and the machine goes into sleep mode. When I connect the charger, it reports Battery: 0 %.

Is this normal behaviour that just have to live with?

Or is there something I can do to fix it?

Best regards,

PS. I recently discovered that I can turn the display off and still continue writing. This is great if Iím on the road; how much can I hope to extend the battery this way? Does the display account for a large part of the battery drainage?

02-25-2005, 02:23 PM
Tried a different battery?

02-25-2005, 02:27 PM
No. I purchased the PowerBook almost exactly 2 years ago. Have never tried a different battery. I recently reset the PMU (Power Management Unit) to solve a different problem. But the behaviour that Iím describing is the same before and after.

02-25-2005, 02:29 PM
Did you take the battery out of the laptop before you reset the PMU?

You need to try a different battery in the laptop, and try your battery in someone else's laptop. This is how to determine if the problem is the battery or the laptop.

02-25-2005, 02:36 PM
You need to try a different battery in the laptop, and try your battery in someone else's laptop.

Yep, when resetting the PMU I followed Appleís instructions precisely, removing the battery.

Iíll try switching batteries as you suggest. Yellow, have you ever encountered this behaviour? It does seem a bit peculiar. :confused:

02-25-2005, 02:38 PM
Nope. Definitely odd. Hopefully it's just the battery flaking out... it IS 2 years old afterall.. it could be getting close to failing completely.

02-25-2005, 05:01 PM
The symptoms you report sound exactly like those of a battery near the end of its useful life.
Search the main macosxhints site for: battery
and you will find articles talking about the lifetime of Lithium batteries and some scripts that report on the detailed status of the battery - in particular the capacity (which decreases gradually with use).

02-25-2005, 05:51 PM
the battery is toast. it'll start cutting out at greater and greater percentages (ie: 50%, then 53%, 55%, etc.) until you'll barely get 5 minutes out of the thing.

2 years is about double what apple admits their batteries should last. if i were you i'd invest in a new battery, and keep that one for emergencies or that last 20 minutes of juice you need to finish a long movie on a plane.


02-26-2005, 02:15 AM
Ok, Iíve been warned. Iíll check with my dealer about the cost of a new battery. And Iíll test the PowerBook, switching batteries with a friend. But what youíre saying does make sense -- and, yes, the battery percentage at which it cuts seems to be increasing.

Well, I guess few things last forever.


03-11-2005, 09:24 PM
I'm having a similar problem with the battery on my 12" Powerbook. Granted I've had it for over 1.5 years and the battery is lasting about as long as I'd expect it to; I just wish the battery estimation utility was more accurate.

My last notebook (Sony VAIO) sucked in a number of ways, but it did at least accurately estimate my battery life, even when my battery only lasted about 20 minutes. I've tried recalibrating the powerbook's battery many times according to the directions at http://docs.info.apple.com/article.html?artnum=86284 but it doesn't seem to help.

I've included a screenshot from the X-Charge utility to show just how the recalibration procedure does NOT work. The thing is, ever since new this battery has very rarely, if ever, kept going below 30%.

Oh well,
- Andrew.