12" Powerbook Question

[white89gt]

I'm kind of new to the Mac scene so please forgive if this is a stupid question. Do the 12" G4 Powerbooks have CMOS of BIOS batteries? If so, is it easily accessible or will the guys at an apple store have to change it for me?

 

[mkrishnan]

I'm kind of new to the Mac scene so please forgive if this is a stupid question. Do the 12" G4 Powerbooks have CMOS of BIOS batteries? If so, is it easily accessible or will the guys at an apple store have to change it for me?

They have non-volatile ram, and they do have a battery of some sort, I think, which is not easily user-accessible, that helps them remember the date and time. I have a service manual for the 12" iBook...the layout is fairly similar. I'll dig and see where it is for you.

EDIT: Actually, now I'm not so so sure. I think there is a battery of some kind, besides the main system battery, that handles the clock. But I don't know where. You know you're not going to have to replace it very often, right?

 

[macEfan]

yes, they have batteries and they last 5- 10 years. I believe they are called P-Ram batteries. Powerbooks also have a capacitor inside them that lets them run for about 1 minute so you can switch out batteries, etc. I find that feature really cool. And bios/Cmos are windows terms,as I said earlier, the mac term is PRAM.

Oh and BTW the ibook has NO internal clock battery as far as I know. It relies on the ibook's main battery to store clock time, system preferences, etc.

 

[mkrishnan]

Powerbooks also have a capacitor inside them that lets them run for about 1 minute so you can switch out batteries, etc. ... Oh and BTW the ibook has NO internal clock battery as far as I know. It relies on the ibook's main battery to store clock time, system preferences, etc.

Two minor points:

1) This came up before, and I'm fairly sure that only the two larger PB's have this switch-out reserve battery feature, and not the 12".

2) I don't know about the last point you made, regarding the iBook. I can say that it doesn't forget what time it is or get off in time if you shut it down, take the battery out, and put it back in at a later time. It has some sort of mechanism to retain at least system time. System preferences, though, are stored on the HD in all these cases. And any open firmware options are stored in non-volatile RAM. So the battery isn't needed for either of these things.

 

[mduser63]

Two minor points:

1) This came up before, and I'm fairly sure that only the two larger PB's have this switch-out reserve battery feature, and not the 12".

You are correct. The 12" PB doesn't let you switch batteries in sleep mode like the 15" 17" models do.

 

[white89gt]

The reason I was asking is because the battery on my girlfriend's g4 powerbook ran all the way down over the weekend while we were out of town. When I turned it back on after charging it back up the system clock had been reset to December 31, 1969. Coming from a PC background, I thought that it was the BIOS battery. I guess the question I was really asking was if the battery goes completely dead will the system clock reset?

 

[mkrishnan]

The reason I was asking is because the battery on my girlfriend's g4 powerbook ran all the way down over the weekend while we were out of town. When I turned it back on after charging it back up the system clock had been reset to December 31, 1969. Coming from a PC background, I thought that it was the BIOS battery. I guess the question I was really asking was if the battery goes completely dead will the system clock reset?

This is strange... I've never done this to my iBook G4, but let me tell you what happens on current Macs. I don't know if this is an aluminum or titanium PB G4. What I'm saying applies to the Alu one and may or may not apply to the Ti one.

1. When running on battery, you should get a warning window at approximately 5%, to go to charger.

2. At approximately 0% the computer will automatically go to sleep. Mid-cycle, the powerbooks, at least, got the ability to go to "safe sleep" -- which is to say, that when it goes to sleep, it prepares for the possibility of hibernation (saves RAM content to disk). Macs don't have a separate hibernate mode. They do this automatically without user intervention.

In either event, the battery has additional capacity to last, typically, about two days in sleep mode, I think? But it won't turn back on until it's plugged into a power source. This is at 0%. So you should really never end up in a situation where it completely runs down.

3. In principle, though, with older G4 Powerbooks or iBooks, if it stays in this state too long, it will eventually basically crash, and have to be rebooted. I guess this is what you're describing. I have personally never done this, but you can set your Mac to get system time from the network during boot (presuming it is available). I think what you're describing was actually a fluke.

The thing is... Macs use disk journaling and so on. You really don't ever want to let what you're describing happen. They give you plenty of options to avoid it. Resetting the clock isn't the reason. You're just putting your Mac in danger of corrupting important data, if you let this happen.

I don't know if any of this helps. It's possible that what you're describing happened because of a dead clock battery. I think it might also be a fluke unrelated to that. In either event, hopefully, it helps you know how the process is supposed to work on Macs. But what you're describing should basically never be an issue on a current Mac laptop, or on an MBP.