iBook clock—won't hold date or time

My school has ~15 iBook G3's(600 MHZ, 128 MB RAM, OS X 10.2.8) that are suddenly unable to hold the date or time. They are plugged in constantly, batteries in, and are always on. I know that with the Pismos, there are PRAM batteries that you can replace, but if I read Apple's support pages right, there aren't any in the iBooks. How does this happen? How easy is the fix?

TIA. I appreciate it.

mick4394 said:

Is it possible that they are set to automatically set the time and date via network, but do not have a network connection?

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It may be. I haven't been able to poke through System Preferences lately. And I do know that when they are asleep( i.e. 97.5% 0f the time), they lose the network connection even though the AirPort is, oh, three feet away . I'll have to look into this come Monday.

WildCowboy said:

If I recall correctly, those iBooks do not in fact have a PRAM battery and instead rely on a small capacitor to provide just enough juice to retain that data for a short time in the absence of any other power source.

Try resetting the PMU. Do the batteries work?

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The menu bar says two or three hours for most of the batteries, but I say different for a good hunk of them. A few probably last that long, but most are lucky to get a half an hour to an hour.

WildCowboy said:

I have an iBook 500 that gets 10 minutes of juice on its battery. I'll sometimes unplug while it's sleeping if I need the outlet for something else, and forget to plug it back in when I'm done. It of course dies pretty quickly even though it's sleeping, and when I turn it back on a day or so later, it's forgotten the date and time. But it quickly connects to my wireless network and straightens itself out.

And yes, they will of course lose the AirPort connection while sleeping...they're asleep.

But if your machines are powered the whole time, I don't know why they'd be losing the date and time.

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I couldn't figure this quite out either...Yes, after three or so years of being heavily battery-used, it would make sense that they would lose the date and time after dying on the battery, but now that they're stationary and plugged in, it would make sense that they would keep the date—the capacitor would be constantly charged, no? So unless there are spontaneous power outages only during the night, it doesn't make sense unless the PMU is becoming unusable. However, wouldn't that also prevent them from booting? I think as a temporary fix we'll just reset the PMU and set them to set themselves by the network.

Thanks again.