eMacs have a 3.6V PRAM battery and some sources indicate that when the voltage starts to drop that they may have trouble booting. Will an eMac work without a battery?


No. I measured the voltage across the power pins before and after installing a new battery and observed a change from 0V to 3.6V. The three pins for the power switch are 3.6V, ground and ground, with this potential difference coming from the PRAM battery. Without a battery installed (or with a battery that's severely depleted) closing the switch does nothing and the machine will not power on or show any signs of life.


Yes, I pulled both dead pram batteries our of my emacs, they boot fine, just don’t keep settings when unplugged.

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    Wonder if there's differences between models then. Will have to get the model code for mine
    – Matt Lacey
    Jan 19 '20 at 5:48

I just started an eMac that has not run for 2 years. Even at that time the battery was kaput; it couldn't keep time and you had to set the time.

It started just fine for me, several times over and over.

However when I plugged in this eMac, the power strip happened to be in a location that is very dark. I could see a minor arc flash as the plug made contact. Something is powered up 24x7, and it has a capacitor!

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