I want to power 9V DC guitar pedals using a 12V lead acid battery and would like some advice on this. I guess that I need to know the impedance of the pedals at the power input in order to make an accurate potential divider. I am concerned that if the power input impedance of the pedals is low then I will need a low value resistor shorting the positive battery terminal to the negative and this will then drain the battery quickly and heat the resistor. Any suggestions welcomed. Thanks