motor free amps at voltages less than 12

[Ether]

Does anyone out there have data to share about the free-speed current of FRC motors being operated at voltages less than 12?

For example, let's say you have an unloaded CIM with 12 volts applied. Per the spec, the free current is 2.7 amps. Now, as you reduce the applied voltage, what does the plot of free amps vs applied voltage look like?

... and how might this differ from a Fisher Price 0673, which has a very high free speed and an internal cooling fan pumping air.


PS - yes, I already know that a first approximation is that the ratio of free current to applied volts is constant, equal to the ratio of free_current_at_spec_voltage to spec_voltage.