I use LTSpice, and vaguely remember there was a way to make a voltage (or current) source depend on either another source in the circuit, or to follow some function of time. I think it's either a source parameter, or a command line placed in the schematic. Does anybody know how to do this? I tried searching the LTSpice Yahoo group but didn't find what I'm after. TIA, RB FYI, I am trying to model the behavior of a NiCd battery in a charger. I have an equation for battery voltage vs. charge state.