This type of information can be found on the Technical Product Specification for each NUC and you can also find more information in regard to power in the BIOS. Is there any specific NUC that you want to get this information?
To answer your question, there are no current sensors in the system; there are only voltage sensors. Yea, I know that voltage sensors can be used to measure current, but it takes multiple voltage sensors to implement a single current sensor and there are precious few voltage sensors available. If you really want to measure Current, you are going to have to do so using a meter at the external DC input point or at the brick's AC input point (using, for example, a Kill-A-Watt device, which is what I use).
With regards to the voltage sensors, there are many tools that you can use to monitor these sensors. The only one that properly displays them is AIDA64. There are free tools that you can use (Alfredo's SpeedFan, CPUID's HWMonitor, HWiNFO32/64, Open HW Monitor, etc.), but remember that you get what you pay for. These tools might understand how to program and read the registers of the Super I/O chip, but they rarely understand how the sensors in the Super I/O chip are actually being used by the board - and this regularly results in the display of improperly-interpreted temperature and voltage sensors - and, in fact, often the display of non-existent (or unused) sensors.
Hope this helps,
That was sad to hear. Had hoped that such an advanced machine as the NUC, should have some concept of energy usage.
If I add a simple power sensor would it be possible to add the sensing internally over say USB or are there any other ports available inside the case that could be used an I2C bus for example?
Here's a summary of the SMBus and I2C exposure across the various NUC models:
NUC6i7KY Exposes only CEC and front panel buttons and LEDs.
NUC6i5SY Exposes I2C via NFC Header.
NUC6i3SY Exposes I2C via NFC Header.
NUC5i7RY Exposes SMBus via NFC Header.
NUC5i5RY Exposes SMBus via NFC Header.
NUC5i3RY Exposes SMBus via NFC Header.
NUC5i5MY Exposes SMBus and I2C via Low-Speed Custom Solutions Header.
NUC5i3MY Exposes SMBus and I2C via Low-Speed Custom Solutions Header.
NUC5PPY Exposes SMBus via NFC Header.
NUC5PGY Exposes SMBus via NFC Header.
NUC5CPY Exposes SMBus via NFC Header.
DN2820FY No exposure.
DE3815TY Exposes SMBus and I2C via Custom Solutions Header.
DCP847SK-DY No exposure.
D54250WY No exposure.
D53427RK-HY No exposure.
D34010WY No exposure.
D33217GK-IY No exposure.
D33217CK-BY No exposure.
As you can see, only three models support Custom Solutions Headers and make access to these buses easily available. I am thinking it will take a lot of work to make use of the exposures via the NFC headers.
Hope this helps,