Was just working on another one of these iMacs and this one won't even power up. Tested everything I can...had to bring it in the office and they replaced the battery. I assume this is that little 3.5v battery I've seen.

My question is, does that render a iMac powerless if it has no juice left? I'm still learning about the Mac everyday, but from what I know the main thing that causes no power (can't even power up) is if the analog board is bad. I thought that small battery was only used to hold other settings like the clock time.

Thanks.

The battery is only used when the power cable itself is unplugged, in my comp (not an iMac though), when you turn the power off there's still a small current running through my motherboard which keeps the settings and time alive. When I'd plug out the cable the battery should start taking over. So when you don't have a battery it shouldn't matter. Not sure if this is the same with iMacs though.

I am not sure about the new Intel iMacs with the EPI loader, but the section of that keeps system time ALSO controls the start up process. So if the battery dies, the system won't start. This is not unheard of, but rare. Usually if a system won't boot it is because:

1) Not plugged in
2) Logic board is bad

98% of the time...its #1.

I assume this is only if it's plugged and powered on right? The user usually turns it off at the end of the day...

I usually replace batteries only when the time and date is not saving properly. We check whatever we can (and yes cable is plugged and tested to make sure it's good ). Usually it's the analog board failing when these old iMacs don't have power though. So this is a first for me also. Oh well, learned something new again

Thanks.

Nope... there's always a slight current going through your motherboard that keeps settings alive. That slight current is also used to wake up your powersupply for it to really power on and start your pc when you press THE button