July 22, 2005 12:18 AM PDT

iPod Special Report: Batteries: Charging, maintaining capacity, maximizing life; more

by CNET staff

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Draining while sleeping Several users have experienced a problem where the iPod's battery becomes drained while the host Mac (charger) is sleeping. The fact that batteries are routinely being completely discharged then recharged (a full, or "deep" cycle) in this manner may have something to do with the large number of short-lived (16-18 months) iPod battery complaints.

Some precursors regarding this issue:

As previously mentioned, Apple's documentation merely states that the iPod will not charge while the connected Mac is sleeping, not that the unit will discharge during this period of time. Knowledge Base article #61127 says "To charge iPod's battery, simply connect iPod to your Macintosh. The computer must be turned on, and iPod won't charge if the computer goes into sleep mode."

Most readers report that the iPod drains more quickly when it is connected to an off or sleeping Mac than if it is not connected and sitting idle (however, these measurements may be inaccurate - see below). Some have noticed that the iPod's hard drive sometimes spins while connected to a sleeping Mac. Thus it would appear that the iPod remains active while connected to a sleeping Mac, and is perhaps using more power to stay active than is being drawn from the FireWire port.

What's odd is that some readers have reported that the drain occurs even while an iPod is dock-connected to a Mac that is turned off. This would appear to indicate that the iPod is constantly "listening" for a signal from the Dock, depleting its battery in the process. This notion is reinforced by the fact that it is not necessary to turn the iPod on when docking it for an update; even if the "hold" switch is active and the iPod is off, placing the unit in the dock will cause an automatic transfer.

For most, the discharge problem is not persistent, occurring once every few sleep sessions.

Some older models not affected Several readers have reported an absence of this problem with older (first and second generation) iPods connected via a FireWire cable; not the dock.

Ryan La Riviere writes: "I have a second generation (non-dock-based) 10GB iPod. I have, on several occasions, actually used my sleeping (and plugged into an outlet) Titanium PowerBook G4 to charge my iPod via Firewire. If I wanted to charge the iPod while the Titanium PowerBook G4 was not plugged into an outlet, the Titanium PowerBook G4 would have to be awake."

John Merritt writes "I have this problem with my wife's newer 10 GB iPod, but not with my older 10 GB, (pre-dock) iPod."

Another reader writes "I have noticed the same problem with my latest generation iPod but not my second generation iPod."

Using an external FireWire hub allows sleep charging Aside from simply using the AC adapter, the only way to continue charging some iPods while your Mac sleeps is to use an externally powered FireWire hub. This way you can still use a single connection for power and data transfer.

MacFixIt reader Eric Westby writes "I ended up using a powered FireWire hub to solve the problem -- since the hub continues to send power to the iPod/dock even when my G4 is asleep, the iPod is fully charged in the morning even though my G4 has spent the night asleep."

AC adaptor may more fully charge iPod batteries Besides not discharging, the iPod AC adaptor may be able to more fully charge an iPod battery relative to the dock in some cases.

"I have a 10GB second generation iPod. I normally charge by hooking the iPod to my laptop or desktop. Around early Jan of this year it would appear that my iPod would not hold a charge. When hooked up to a computer it would seem like it could never reach full charge on the display. If it did, then it wouldn't hold its charge for more than a couple of hours. I thought the battery was toast. On a fluke, I connected it to the wall charger. After it reached full charge, I was again able to get about 8 hours of playing time. Its like having a new iPod!"

Setting startup time to three hours prior for maximum charge Knowledge Base article #61127 also notes that the iPod is "80 percent charged in about an hour, and fully charged in about 3 hours."

If you want to keep your iPod docked overnight (or for another long, unattended period of time), you can use a utility like iBeeZz to automatically wake your Mac up three hours before you'd like to begin using the iPod. This will provide a full charge - based on Apple's claims - in spite of discharging.

Slow charging because of other devices Several users have noticed slow charging when other FireWire devices are connected. Bob Sutryk writes:

"One other issue that frustrated me for months: Shortly after I put Mac OS X 10.3 on my computer the iPod seemed outrageously slow to charge. After months of dealing with this and sending the iPod in to be fixed, a sharp Apple tech finally discovered that my iSight camera was pulling too much power for both Firewire appliances to handle. Once I unhooked the iSight, the iPod ran like new."

Inaccurate charge measurement Some iPods display an inaccurate battery measurement, though MacFixIt reader Jed and points out that this phenomenon is common with other devices as well:

"The battery meter is often inaccurate. I've found this to be true on my Palm as well: after charging, the battery meter continues to show low charge for a while, gradually increasing over time.?

Meanwhile, Ron Skinner notes that, typical of Li-Ion batteries, inaccuracy may increase with time and the constant use of "shallow charges" :

"Devices equipped with Li-Ion charge indicators--such as the iPod--become increasingly inaccurate when they are shallow charged. All that is required to re-calibrate the gauges is to fully discharge the battery before recharging. However, routinely fully discharging these batteries should be avoided. Their useful life is greatest when subjected to shallow charge cycles."

Extending battery life/getting the most capacity Here a few tips for keeping extending your iPod battery's life, as well as maintaining a maximum full charge level:

Apple recommends that you keep the iPod in a temperature range of 32° F to 95° F (0° C to 35° C) when operational, and a range of -4° F to 113° F (-20° C to 45° C) when stored.
Apple also says that users should charge the battery every 14 to 18 days when not in use in order to keep it ready for use, as the iPod will still drain a minimal amount of power when not on.
Backlighting can use a lot of battery power. If you don't need to use backlighting, turn it off. Choose: Settings > Backlight Timer > Off.
Use the hold switch keep iPod from accidentally waking from sleep and playing songs if its buttons are pressed while being stored
If you leave iPod unattended, press Play/Pause to pause the song. If left playing, iPod will continue to play songs until the battery is drained--particularly if the repeat setting is set to One or All.
Finally, Apple says that the iPod's cache works best with songs of average file sizes (less than 9 MB). If your audio files are large or uncompressed (including AIFF format), you may want to compress them, or use a different compression method, such as MP3 or AAC, when importing them into iTunes.

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