Computer Pulsed shutdown Command on low voltage

[toxsick]

Hi,

I have built a small ITX system which I have running on DC,
I have made my own Lithium ION Battery Pack which is configured to run at 24v,
and sometimes I use it on a 12v battery.

Can anyone help design a circuit which automatically detects my input voltage (12/24v)
and the shutdown voltage can be adjusted by a variable resistor for both voltages.
send a pulse to computer to shutdown...

I could always reconfigure my Lithium Ion battery.. to run at 12v, but higher voltage is good for me.

thanks

 

[crutschow]

Can anyone help design a circuit which automatically detects my input voltage (12/24v)
and the shutdown voltage can be adjusted by a variable resistor for both voltages.

How would you select which shutdown voltage the circuit should operate at?