Thank you for your post.
The ADC-11/12 is a 12 bit unit that has an accuracy of 0.5% over the 2.5 volt range. To measure the 1000 amps we do have a 2000 amp DC current clamp, however the voltage to current ration is 1mV to 1 Amp, with the accuracy the error factor could be ±12.5 mV or 12 A's.
To measure the 120 DC volts you will need to use a contact free attenuator to bring the voltage down and into the ADC-11's voltage range 0 - 2.5 volts.
To measure the 15 volt DC you motor speed you will need to reduce this with a potential divider. This could be achieved by using the terminal board available for the ADC-11/12. It has screw terminals to allow ease on cable connection to the ADC-11.
The ADC-11 has a maximum sampling rate of 10,000 samples per second, what is the maximum sample rate you require? If it is greater then 1 ms, you could use two ada loggers ADC-11, and ADC-16.
The ADC-16 unit is a high resolution datalogger with an accuracy of 0.2%, and resolution of 16 bits plus sign. Therefore the error factor would only be approx 5 amps.