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Mac Forum / General / Hardware / February 2010MacBook Pro Battery/Charging Issues
Lately I've been seeing some odd behavior when it comes to battery life and charging for my MacBook Pro (MB133*/A). None of the behavior is perfectly consistent, but here's a few things I've seen more than a handful of times: 1) Battery life indicator estimates don't seem to be particularly accurate: I may start with an hour and a half of charge, and find 20 minutes later that I'm being given the 10 minute warning. Subsequently, I may find that the battery operates for another half an hour. 2) Sometimes when I operate it unplugged, the battery life indicator simply says "10:00" and doesn't change for some time. 3) Sometimes (in fact, at the moment) even though the machine is plugged into a working outlet, I get "Not Charging" from the battery indicator. I might expect "Charged," given that the power cord is giving me a green light and the battery's hardware indicator lights up to all five levels when pressed, but that's not what I see. 4) Sometimes even when battery hardware indicator shows full charge and/or the software indicator shows time remaining, I'll see sudden hard shutdowns, like you would from a desktop that's suddenly unplugged, rather than the sleep process you usually see from a drained laptop. The machine's just about 20 months old, original battery, so I wouldn't be surprised if the battery needed replacement. However, some of the symptoms here seem unusual compared to past experiences I've had when batteries inevitably wear out. Could I have a problem with either (a) my charger or (b) some kind of on-board hardware that regulates charging behavior? + Weston C <notsew-reversePreceedingAndRemoveThis@canncentral.org>: > Lately I've been seeing some odd behavior when it comes to battery > life and charging for my MacBook Pro (MB133*/A). Are you aware that you can get a bit of info on your battery's health from the System Profiler (About this Mac, then More info)? Under Hardware there is Power, and there is listed your battery information. Have a look and see if it contains a clue.  Signature* Harald Hanche-Olsen <URL:http://www.math.ntnu.no/~hanche/> - It is undesirable to believe a proposition when there is no ground whatsoever for supposing it is true. -- Bertrand Russell > Are you aware that you can get a bit of info on your battery's health > from the System Profiler (About this Mac, then More info)? Under > Hardware there is Power, and there is listed your battery information. > Have a look and see if it contains a clue. The battery "Health Information" lists a "Good" condition and 738 cycles. The same status panel tells me that the battery is fully charged... but if unplug it, we're showing 10:00 again in the Toolbar... and based on several experiences in the last 24 hours, if I leave it unplugged for a few minutes, it'll hard power-off despite the full charge. The inconsistent behavior seems to have consolidated to this sequence. I poked around a bit and found a recommendation to reset the System Management Controller: http://support.apple.com/kb/HT3964 I followed those instructions and zapped the PRAM for good measure. Still have the same behavior. If I had to commit to a guess at this point, it'd be that the SMC hardware has indeed failed in some way, but I'd be happy to hear if there are any other pointers, particularly on two fronts: 1) Is it possible to mess up the SMC reset process? Seemed simple, pretty sure I followed the instructions, but I thought I'd ask 2) Could this be a firmware problem? If so... what's the process for grabbing the current firmware and reflashing the hardware? >> Are you aware that you can get a bit of info on your battery's health >> from the System Profiler (About this Mac, then More info)? Under [quoted text clipped - 27 lines] > 2) Could this be a firmware problem? If so... what's the process for > grabbing the current firmware and reflashing the hardware? The usual reason for behavior like this, especially the sudden shutoff, is that one or more, but not all, of the cells in your battery are dead. It has something to do with the way the battery reports its charge to the computer, it thinks it has more power left than it actually does, so your Mac doesn't have time to shut itself down gracefully. Other people who had similar problems with their computers reported that a replacement battery solved that problem completely. Probably not a firmware issue, but the latest firmware files are all located at http://support.apple.com/downloads/ > > Are you aware that you can get a bit of info on your battery's health > > from the System Profiler (About this Mac, then More info)? Under [quoted text clipped - 3 lines] > The battery "Health Information" lists a "Good" condition and 738 > cycles. 738 cyclyes for an early 2008 MacBook Pro is way past the normal lifetime of the battery. If it says Good with 738 cycles then something is lying. My guess is that the battery microcontroller has false information, either the cycle count is wrong or its condition checking algorithm has misleading inforamtion which makes it produce the wrong result. Given the symptoms I suspect you have a faulty cell and the batter microcontroller isn't reporting things properly. At a minimum, you should try recalibrating the battery, but I expect you will need to replace it. For comparison, mine (mid 2007 MacBook Pro with original battery) is up to 437 cycles and condition says "Replace Soon" but it is still working reasonably well (no sudden dropouts, in the order of two hours of useful life). I'm monitoring it, and expect I will need to replace it once it starts to exhibit worse behaviour. > The same status panel tells me that the battery is fully charged... > but if unplug it, we're showing 10:00 again in the Toolbar... and [quoted text clipped - 10 lines] > I followed those instructions and zapped the PRAM for good measure. > Still have the same behavior. Battery lifetime information is stored in the battery's internal processor, not in the PRAM. > If I had to commit to a guess at this point, it'd be that the SMC > hardware has indeed failed in some way, but I'd be happy to hear if > there are any other pointers, particularly on two fronts: > > 1) Is it possible to mess up the SMC reset process? Seemed simple, > pretty sure I followed the instructions, but I thought I'd ask Not likely. The SMC is only indirectly involved. It is getting bad information from the battery microcontroller. > 2) Could this be a firmware problem? If so... what's the process for > grabbing the current firmware and reflashing the hardware? No. In any case, your model has never had a firmware update so there is no way to reflash its firmware. SignatureDavid Empson dempson@actrix.gen.nz On Feb 17, 6:00 pm, Koronis <kor0...@hotmail.com> wrote: > The usual reason for behavior like this, especially the sudden shutoff, > is that one or more, but not all, of the cells in your battery are > dead.... it thinks it has more power left than it actually does, so your >Mac doesn't have time to shut itself down gracefully. > 738 cyclyes for an early 2008 MacBook Pro is way past the normal > lifetime of the battery. > At a minimum, you should try recalibrating the battery, but I expect you > will need to replace it. It turned out that it was hard to execute the recalibration process in any other manner than "rocky" with the given battery behavior, and this discussion steered me towards confidence that the battery was the problem, so I replaced it. Things generally look pretty good. I'm still seeing the odd "Not Charging" message and a few wide swings in battery life, but I'm not sure it's outside the normal realm. > Lately I've been seeing some odd behavior when it comes to battery > life and charging for my MacBook Pro (MB133*/A). None of the behavior [quoted text clipped - 28 lines] > either (a) my charger or (b) some kind of on-board hardware that > regulates charging behavior? Have you tried recalibrating your battery? Some of those symptoms might be due to the battery controller having the wrong concept of the battery capacity, especially if you never recalibrated it since the computer was new. See <http://www.apple.com/batteries/notebooks.html> for background and links to the calibration procedure. SignatureDavid Empson dempson@actrix.gen.nz |
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