> For example If I use a 100A 50mV shunt how can I tell the software that a 50mV drop = 100A? I
Currently, you can’t (AFAIK). But there have been already more requests in this direction, so perhaps it will get implemented someday.

Just some days ago, I made a similar, but more generic suggestion for external shunts, sensors, etc.:

As it seems impossible to consider all possible external sensors and devices, I suggest a flexible concept of some (say, 10 or 16) user-definable and -nameable “profiles” where free math conversion formulas (and/or even filenames of user-stored lookup tables) can be entered and saved. The already existing temperature conversions could then be made a (pre-defined) part of this concept. (see here)

Anyway, please be aware that even if some kind of such feature would be implemented, it would only work at app level, so it would influence the app display, but not the logged data. (Otherwise, it would have to be implemented at firmware level, but the small firmware memory would surely not allow that amount of extra functionality.) So logging stores always raw data (for example, temperature always in Kelvin); you need to apply your own conversion/postprocessing if necessary.