Archive: October 31st, 2004

Let sleeping iPods die

After a Friday afternoon meeting over at Semantico, I decided to swing by the local Cancom shop and browse through whatever Apple goodies they might have in stock.

I spent a little while sitting in front of the new 17 inch G5 iMac. One of the first things I tried to do was to push the screen upwards. I forget that the screen can now only be tilted but not raised or lowered. Maybe I’m just spoilt by the G4 iMac but I’d really miss the ability to adjust the display height.

Overall, the G5 iMac is a very neat machine. If you were switching from a Windows machine, it would be a whole new world of comfort and ease of use. But if you were upgrading from a G4 iMac, it may seem like a step backwards in terms of ergonomics.

I had my iPod with me and I took my earbuds out long enough to ask about skins and speakers. Once I had finished pestering the shop assistant, I plugged up my ears once more and resumed walking around Brighton.

The iPod had been playing for a total of maybe an hour when it suddenly stopped. The screen showed the image of a battery with a superimposed exclamation mark, international symbol for "you’re out of juice".

This struck me as somewhat strange because I knew for a fact that I had charged it up the previous day. Either my iPod’s battery was giving me less than 10% of its advertised life or else the battery was somehow losing as much power when it was off as when it was on.

There seems to be a whole black art to understanding batteries. You’d need a degree to understand all the vagaries of the science of cells. Nonetheless, I endeavoured in my entirely amateurish way to apply the scientific principle to my particular conundrum.

The first thing to determine was battery life. I charged up my iPod and, once it was charged, I set it to playing.

I’m happy to report that after more than the advertised 12 hours, the iPod was still going strong. I ended up squeezing close to 13 hours of continuous play out of it. Admittedly, that would be considerably shortened in a real-life situation involving starting and stopping as well as forwarding past songs. Still, it was pretty clear that the battery itself was in tip-top shape.

So my problem must be related to how I was charging the iPod. Sure enough, I noticed the following strange behaviour:

I plug my iPod into its dock. The dock is connected to my iMac by FireWire. The iPod charges and remains charged. At the end of the night, I put my iMac to sleep. The iPod also goes to sleep. The next morning, I wake up the iMac. The iPod also wakes up and begins charging again. This is to be expected: some charge is lost even when the iPod is not in use. However, when it continues to charge for hours and hours, it’s clear that something is wrong.

A bit of googling turned up some reports of people with the same problem:

"If he leaves it connected to his G4 overnight (computer turned off), the iPod battery is dead in the morning. If he unplugs it at night the battery is fine in the morning."

There is also an explanation:

"When the computer is off the current flow is reversed and dissipates into the computer via the Firewire port."

So that’s what’s happening. As long as the dock is connected to the Mac and the Mac isn’t awake, the iPod is actively draining its battery down the FireWire cable.

Apple are somewhat economical with the truth when they describe battery charging over FireWire:

"The computer must be turned on. iPod won’t charge if the computer goes to sleep."

They don’t mention that power could actually be drained if the computer goes to sleep.

At least I now have a solution to my problem thanks to my keen detective skills… and Google of course. I need to disconnect the iPod (or the dock) before putting my Mac to sleep. Dashed bothersome, that.