Am I mistaken to assume that you're just trying to think of other sources of power that can be used to power up a machine, and only thought of a CMOS battery as a possibility? If So, a Power inverter (or even, for short periods, a UPS), would facilitate that. However, Ithink you're also asking whether a computer can be remotely powered up without having it's power cord plugged in.
I think I now know that if you leave a desktop plugged in and you have it hooked to a router with a wireless network enabled, somebody can tap into the Network card, wake the machine up and access the PC.
I'm not sure, but I don't think a Wireless network card can be used as a WOL source, since the card itself needs to be connected to the network (facilitated with wires in the wired case) to be accessed by other computers. a more likely method would be to access the router that that wireless card is connecting to, and (possibly, if the card can recieve packets while the computer is off) somehow get it to turn on. It's possible with wired NICs, simply because their is no extra device (antenna) to power, it just needs a little standby power to monitor the network. However, a wireless card needs to essentially have full-power just to facilitate waking the computer, since it will need to remain connected to a wireless network.
More recently, I was using a laptop that I would power down and unplug at night, only to find odd things in the morning. So I was suspecting a secondary battery might allow the startup and access as I specified above.
So- are we actually talking about the laptops main battery? because that is designed to power up the laptop. In addition, bear in mind that a desktop PC, in almost all cases, requires far more power then a Laptop (for obvious reasons, not the least of which is the fact that, for the laptop, power conservation is critical to good productivity. On the other hand, Power management in desktop computers is more of a green initiative, (one with the side effect of possibly reducing electricity bills).
I'm not sure if it has been mentioned, but the best way to secure a wireless network from access is to use an encrypting protocol, such as WPA or WEP. (I can't recall the good one off the top of my head. I want to say WEP, though).
What about a ¨... bridge battery. This battery is only found within portable computers and is used as a temporary backup for the main battery. This allows you to remove the main battery and replace it with a good battery without having to turn off the computer.¨
Problem with that is that the secondary battery requires that the computer be put on standby/suspended (most do it automatically), to conserve power draw.
I believe it was said before, but I believe your looking in the wrong direction. Features used to remotely boot computer can always be disabled, wireless networks can be secured, and so forth, what you're looking for (and your comments on your networking experience) sounds like you've skipped checking those alternatives(you believe that networks are capable of much more then they really are, as well- researching things on the net almost surely results in some bad information).
