I have a similar issue with my unit. I purchased it used and it was very off on the low end. I emailed their tech support and they sent me a document on how to calibrate. below is the procedure.
Array 3715A Electronic Load Calibration Methods
1. Calibration Equipments
PC 1PC;
3311 1PC;
Power Cable 1PC;
Large Current Power Source NL08-30;
High-voltage Voltage Source ARRAY 3665A;
DC Electronic Load ARRAY 3721A;
Flat Head Screw Driver 1PC;
Fastening Adhesive Glue 1Bottle;
Standard Current Sampling Resistance 1mΩ;
Digital Multi-meter;
2. Calibration Methods
A. Current Regulation
Connect the Large Current Power Source NL08-30, the 3721A Electronic Load, the Standard Current Sampling Resistance and the 3715A in series.
Hold down the decimal point “.” on the keyboard, press the switch of the power supply and select the calibration current option.
a. Input 0.5A in CC mode of the 3721A, read the current value on the voltage meter, input it into 3715A and confirm;
Input 2.5A in CC mode of the 3721A, read the current value on the voltage meter, input it into 3715A and confirm;
Input 25A in CC mode of the 3721A, read the current value on the voltage meter, input it into 3715A and confirm;
b. Read the current value on the voltage meter directly, input it into 3715A and confirm; (This is the low point of the calibration current DA.)
Read the current value on the voltage meter directly again, input it into 3715A and confirm; (This is the high point of the calibration current DA.)
B. Voltage Regulation
Connect the High-voltage Voltage Source ARRAY 3665A, the voltage meter and the 3715A in parallel.
c. Regulate the voltage value of the voltage source to 0.3V, read the current value on the voltage meter, input it into 3715A and confirm;
Regulate the voltage value of the voltage source to 3.6V, read the current value on the voltage meter, input it into 3715A and confirm;
Regulate the voltage value of the voltage source to 4.5V, read the current value on the voltage meter, input it into 3715A and confirm;
Regulate the voltage value of the voltage source to 38V, read the current value on the voltage meter, input it into 3715A and confirm;
Regulate the voltage value of the voltage source to 42V, read the current value on the voltage meter, input it into 3715A and confirm;
Regulate the voltage value of the voltage source to 200V, read the current value on the voltage meter, input it into 3715A and confirm;
d. Read the voltage value on the voltage meter directly, input it into 3715A and confirm; (This is the low point of the calibration voltage DA.)
Read the voltage value on the voltage meter directly again, input it into 3715A and confirm; (This is the high point of the calibration voltage DA.)
3. Current Accuracy
0~2.999A should meet the requirements ±(0.2%±5mA); and 3~30.00A should meet the requirements ±(0.2%±30mA). Otherwise it is unqualified.
4. Voltage Accuracy
0~3.999V should meet the requirements ±(0.2%±3mV); and 4~35.99V should meet the requirements ±(0.2%±30mV); 36.0~360.0V should meet the requirements ±(0.2%±300mV). Otherwise it is unqualified.