Electronic load question

[jayk]

I'm thinking about getting a benchtop electronic load like an itech 8511A+ or Rigol DL3000.  Most electronic loads are specified with a minimum voltage at two different ranges: something like 0.14V @ 3A or 1.4A @ 30A.  If I'm on the 30A range, will I be able to get to a lower voltage if I'm below the rated current (i.e. 0.7V @ 15A)?  Has anyone tried this? 

[KrudyZ]

Very likely as most (all?) modern electronic loads use MOSFETs as pass transistors. The forward voltage drop will therefore be limited by Rdson plus the current balancing series resistors and sense resistors.
This should be documented in the manual for the load. THere usually is a VI graph that shows the range of load voltages and currents that the instrument can handle.

[JohnPi]

You can go to 0 (and below) by just putting an external supply (with the current handling capability) in series with it, and setting that supply's output to a low value (e.g. 1 V).