[Eds note: this list of postings from http://www.macintouch.com includes some good tips on battery life for portables like the iBook and the PowerBook]

Adrian Langford
There are a few options for Charles Shelor to explore in his quest for longer battery life.

First off is to see what life he gets after calibration i.e. allow the battery to discharge to point where the 'book puts itself to sleep (it's recommended to do this about monthly - regular deep discharges will shorten life of Li-Ion cell). He may also find performance improves after a few charge cycles. Has he turned off Bluetooth and Airport if installed?

What setting is his screen brightness? He doesn't mention it but this is the most significant variable for battery life. Depending on external light the screen is fine at just a few 'bars' on the indicator.

What is the energy saver setting? It should be set to 'automatic' or 'battery power'. Even better he should check if his recording set-up works ok with 'longest battery performance' selected (but I suspect he won't want screen to dim while he monitors recording).

Michael Olshansky
In response to Charles Shelor's issues regarding battery life, one thing he needs to do is Calibrate the battery as soon as possible. To do this, he needs to fully charge the battery, then use the system like normal (without AC) until the system goes into "Deep Sleep." Once this happens, he needs to plug in the AC and let the system fully charge. This will complete the Calibration process and he should see an improvement in overall battery life. This only needs to be done once.

A stock unit like his should net around 3 hours of battery life with the screen at full brightness and the Processor Performance (located in the Energy Saver Pref Panel) set to either Reduced or Automatic. The 5400 RPM drive WILL reduce battery life, so I would strongly advise he check the "Put hard disc(s) to sleep when possible" option, too. The MBox will also put additional strain on battery life. Tips to improve battery life include the above, as well as reducing screen brightness ever so slightly.


Brian Monroney
I also have an Aluminum PowerBook G4 and have been disappointed in the battery life compared to my previous Wallstreet, where I could load up two batteries and use it for an entire coast-to-coast flight without a hitch. I use my G4 PowerBook for remote audio capture as well, with a Metric Halo Mobile I/O which likely draws more power than the previous reader's digidesign mBox. The solution for live concert recording without access to AC power is to buy some sort of extended-life external battery, such as the Valence N-Charge or the Electrovaya PowerPad. They're fairly expensive, around US$300-500. A colleague of mine uses the N-Charge with his TiBook and mBox and has had good results.


Richard Wanderman
Apple recommends "conditioning" the batteries in its portables and this conditioning really does work:
1. charge battery fully
2. run on battery only until machine shuts down (drain battery completely)
3. charge battery fully
4. run as normal, battery, AC, whatever

I do this conditioning thing often.

These days, many people use PowerBooks and iBooks plugged in most of the time and so, the battery doesn't get a complete cycle very often. Conditioning gives the battery a cycle through its complete range of capacity and it really does work.

You can resurect a completely dead battery this way but you can add life to a battery like the one Charles describes by doing it any time.


Mike Cohen
Charles Shelor reports 1 1/2 hour battery life with his new PowerBook G4 but also mentions that he is using a USB powered MBOX audio capture. Connecting any external USB or FireWire powered device will reduce the battery life. I also find that having Bluetooth turned on or the screen brightness all the ways up reduces the battery life on my 12". I find that I get the best battery life (around 3:00+) if I keep the screen brightness as low as possible. The additional RAM & larger drive may also be reducing his battery life, although there isn't much he can do in that case.


Dennis Sweet
I have a 1.25 GHz Powerbook and have also been disappointed by the short battery life. I don't think that I have ever gotten even two hours out of my 1.25 GHz Powerbook. My old iBook (the original 300MHz model) gave me well over three hours of run time on a new battery. I recently replaced its battery with a more powerful model (iGo) and routinely get between four and five hours.

When I first noticed this problem, I investigated why this may be true and found the answer in Mactracker (the Macintosh device database). Between the last 15" Titanium Powerbook and the first Aluminum Powerbook, Apple downsized the battery from 61 WattHours to 46 WattHours. A decrease of 25%! In my opinion, the major problem is not enough battery. I find this disappointing because Apple was one of the first manufacturers to offer dual batteries for extended run time (Powerbook 540c).

My solution is to wait for a third party to come out with a more powerful battery for the AL Powerbooks. In the meantime, I would suggest trying one of the "powerplate" type external batteries on the market (although I haven't personally used any). They plug into the power supply connector of your computer and sit under the computer in its case.


Harris Upham
I think Mr. Shelor is expecting a bit too much....Running a (potentially) processor intensive, certainly i/o intensive application like most audio software, as well as supplying power to outboard hardware such as an mbox, I would not expect a lot of battery life.

I can run my 17" PowerBook for well over 3 hours, if I've allowed the system to conserve all possible power and (this is the important part) if I do my part in not running particularly demanding software. In a usage scheme like Charles is describing, I would expect that runtime to drop considerably.

Battery conservation measures in the system software do not necessarily mean that power will be saved- they simply give the system more authority to save power when little or no work is being done. This all goes out the window when you are expecting the system to perform more difficult work like continuous recording- then it's just a question of hauling in enough power to do the job.

I strongly suggest using an external battery, something like the n-charge unit from Valence. I don't own one, but have seen them used with great results.


Mike McCarthy
Just saw the question on PowerBook G4 battery times on a new machine being rather low. Are you sure the Wireless and/or Bluetooth is turned off? If I don't do that on mine, I get about 1 and a half hours. Once turned off, it's closer to 3, although I haven't rigorously tested it.


Jerry Hom
For what it's worth, I have a 15" Aluminum PB which gives me 2 hours max with intensive use (any modern 3D game). Purchased in November, 2003, the specs are: 1GHz, 256MB, 4200 RPM disk, built-in display at half brightness, 2nd display at 1024x768, without backlit keyboard, with USB keyboard/mouse, with external self-powered speakers. I can't say definitively, but I think Charles' PB battery life is within the ballpark.

Some factors to consider are the faster RPM disk, faster CPU, display brightness level, backlit keyboard, Airport Extreme, and Bluetooth. Turning these factors off or to lower levels will help battery life. To a lesser degree, reducing the RAM (just enough to avoid disk swapping) also reduces current draw from the battery. There are also differences in battery build quality. They're very imprecise devices.


Jack Dietz
The runtime of 5 hours that Apple quotes is in my opinion based on normal airplane laptop usage: typing in one application for a long time without using the wireless capabilities of the laptop. With the hard disk spun down, the wireless ports off, the brightness reduced, and no peripherals attached I can get close to that figure.

The MBOX, from a quick look at the spec sheet, specifies that it shouldn't be attached to a passive USB hub. That implies that it draws a significant amount of +5 volt power to run, perhaps close to 5 watts. I'm assuming that when it's recording it also keeps the hard disk active, which adds to the power consumption.

My suggestions from observations on my 12" Powerbook:
1. More memory than applications helps a lot. That extra DIMM could make a big difference. Quit any applications (including menu bar frobs) you aren't using.
2. Make sure the Energy Saver control panel has you on the Reduced CPU Performance setting when you're on battery power. (You may have to
experiment to see if the software runs correctly on this setting.)
3. Turn off AirPort and Bluetooth. This can get me an extra hour of battery power.
4. Reduce the screen brightness. I can get an extra half hour of battery power if I turn the brightness down below half.

Other ideas, if those simple solutions don't get you up to 3 hours:
1. You could find a Firewire hard drive with its own rechargeable battery, allowing your laptop's hard drive to spin down and save power. (MPD AMS 2.5" Rechargable FireWire enclosure Fast Oxford 911 chip appears to be one.)
2. The FAQ for the ProTools software suggests using a hard disk without Mac OS X 10.3's Journaling feature enabled for the media drive. That might increase write speed and decrease disk seeks.
3. You could find or build remote power for the MBOX. One method would be a powered USB hub with battery power; another would be a box with batteries that feeds the USB +5 power wire going to the MBOX and passes through the data wires and ground wire from the laptop.


Mahboud Zabetian
In response to the PB15" user who only gets an 1.5 hours of battery life, I typically get over 3 hours on my 1GHz 17". I get 2.25 hours if the LCD brightness is set all the way. I get a little over 3 if I set the LCD panel to one notch from off.

Running QuickTime via QT Player or a JPEG viewer usually kicks on the fan and then battery life drops to the lower part of 2 hours.

I also try not to run too many apps if I care about battery life. Some apps seem to make the CPU drain more power.


Kynan Shook
Though the capacity and energy density of batteries continues to increase, so does the amount of power needed for your computer. Screens are bigger, backlights are brighter, processors are faster, hard drives run at higher RPMs, graphics cards drink more power, and your memory has more bits. Add to this new technologies like Airport, Bluetooth, backlit keyboards, and bus-powered USB and Firewire devices, and batteries don't stand a chance against today's laptops!

Anyway, there are a million and one ways to save power, I'll list as many as I can think of offhand.

First of all, dim your screen. I take notes in classes all day, and I can easily hit 3 or 4 hours if I keep my backlight on only just 1 notch. If I really need to squeeze a lot of time out of a battery, I'll even turn the backlight completely off and type blind, assuming I don't have a lot of complex mathematical formulas or anything like that. I then turn it on briefly every few minutes to check for major typos, etc. Also, have your backlight set to turn off after 1 minute of inactivity. If all you're doing is recording music, you can probably just turn the backlight off, and maybe check back every 10 minutes or so to make sure that things are still working properly. I have gotten used to always having the backlight only barely on in the interest of saving power, even if I know I can plug in easily; I've just gotten used to normally keeping my display dim. Those with older eyes might not adjust to this as easily; in that case, there are external batteries that have a capacity several times larger than that of the normal battery. The disadvantage is they are much larger, and have to be carted around separately.

The next big power-hungry monster in your computer is the CPU. In Energy Saver, set processor performance to Reduced. This will slow your clock speed somewhat, and will disable the L3 cache on some machines. If you have the CHUD tools installed from the Dev Tools CD, you can manually enable and disable your L2 and L3 caches, and turn on or off processor napping. I'd recommend turning on processor napping and the L2 cache (which gives a nice boost to performance), and turning off the L3 cache if you have one (which doesn't have a very large impact on performance). This should be the same as what Energy Saver does automatically at the "Reduced" setting, except Energy Saver will automatically adjust it back up to full speed when you plug in again.

Also in Energy saver, allow the hard drive to sleep. The hard drive is also a big consumer, especially the 5400 RPM drives, such as the one Charles has. The stock 4200 RPM drive will probably get you a few more minutes, depending on your usage. If you want, you can even edit the appropriate plist at

/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist.

You can also use the command line tool pmset to adjust power settings to ranges outside what Energy Saver allows. You might consider turning the disk sleep time down to 1 or 2 minutes; just be sure that once the drive spins down, it stays spun down for several minutes. If it is spinning down and back up very frequently, you'll end up drawing even more power than just letting it run.

The optical drive will draw a lot if you have a disk in the drive. Remove any disk you're not using, and if you're going to be using the hard drive anyway, you can save power by imaging the CD or DVD to your hard drive while on AC power, and using the image instead of the disc itself.

If you're not using them, turn off Bluetooth and Airport via their menu items or the appropriate preference pane. You'll save a little bit of power by doing this.

Also, you can save a fair amount of power by removing anything you don't need; USB and Firewire devices, for example. Don't use the modem if you don't need it, turn off your keyboard backlight, mute your sound (and try to prevent sounds from being triggered; after 20 seconds, the sound circuitry will deactivate in most Apple portables, but in general, it will power back up if an application generates a sound, even if sound is muted).

Also, use your battery as little as possible; your battery life is limited, typical is 2-4 years, but it depends largely on how much you run off your battery. However, battery care is another looong topic, so I won't even start to go into it now.