A shunt resistor would be the most accuracy, until the power resistor becomes to much. Above say an amp then a current clamp would be a better option.
The most accuracy logger to do this would be the ADC-24. Has 24 bit ADC, with multi voltage ranges.
( 7 ranges from ±39 mV to ±2500 mV)
If you need a fast current logger you could use the picolog 1216, upto 1kS/s and has 0-2.5v inputs.
We don't sell shunt resistors. There are terminal board that are sold with logger to make it easier to connect the inputs. Are is user guide for each of the terminal boards, depending which logger you use.
Picolog 1000- https://www.picotech.com/download/manuals/DO161-SmallTerminalBoardUsersGuide-3.pdf1. Do the dataloggers have a calibration certificate?
These can order in addition to the datalogger. Our certificates are traceable to UK national standards(UKAS).
We can only issue certificates for the loggers themselves not with the sensors. If you need the logger with the sensors calibrated, you can get this done by a calibration house.2. Can they be used for compliance testing?
I would expect so, if our or another lab's calibration certificate would be accepted for the compliance testing.3. How reliable are they?
As these are PC based, its really about the reliability your PC. Our picolog software has been tested logging data for weeks at a time.