A current measurement system for determining the no-load offset of a circuit, the system comprising: an amplifier having a first input (V +) and a second input (V -) and configured to provide an output (V out) in accordance with the first and second inputs thereto; a shunt resistor (R shunt) having an input and an output, the input of the shunt resistor being configured to be connected to the first input (V +) of the amplifier and the output of the shunt resistor being configured to be connected to the second input (V -) of the amplifier; and a microcontroller configured to receive the output (V out) from the amplifier; characterized in that the system further comprises: a switch (S 1) connected to the microcontroller, a first side of said switch being configured to be connected to one of the input and output of the shunt resistor (R shunt); a small value resistor (R cal) being of three orders of magnitude greater than the shunt resistor (R shunt), a first end of the small value resistor (R cal) being connected to the other one of the input and output of the shunt resistor (R shunt), and a second end of the small value resistor (R cal) being connected to a second side of the switch (S 1); and in that the switch (S 1) is configured to be actuated by the microcontroller to selectively break the connection between its side of the shunt resistor (R shunt) and one of the first and second inputs of the amplifier such that the other side of the shunt resistor (R shunt) is connected to the other one of the first and second inputs of the amplifier as normal, and is also connected to the said one of the first and second inputs of the amplifier through the small value resistor (R cal). an amplifier having a first input (V +) and a second input (V -) and configured to provide an output (V out) in accordance with the first and second inputs thereto; a shunt resistor (R shunt) having an input and an output, the input of the shunt resistor being configured to be connected to the first input (V +) of the amplifier and the output of the shunt resistor being configured to be connected to the second input (V -) of the amplifier; and a microcontroller configured to receive the output (V out) from the amplifier; characterized in that the system further comprises: a switch (S 1) connected to the microcontroller, a first side of said switch being configured to be connected to one of the input and output of the shunt resistor (R shunt); a small value resistor (R cal) being of three orders of magnitude greater than the shunt resistor (R shunt), a first end of the small value resistor (R cal) being connected to the other one of the input and output of the shunt resistor (R shunt), and a second end of the small value resistor (R cal) being connected to a second side of the switch (S 1); and in that the switch (S 1) is configured to be actuated by the microcontroller to selectively break the connection between its side of the shunt resistor (R shunt) and one of the first and second inputs of the amplifier such that the other side of the shunt resistor (R shunt) is connected to the other one of the first and second inputs of the amplifier as normal, and is also connected to the said one of the first and second inputs of the amplifier through the small value resistor (R cal). a switch (S 1) connected to the microcontroller, a first side of said switch being configured to be connected to one of the input and output of the shunt resistor (R shunt); a small value resistor (R cal) being of three orders of magnitude greater than the shunt resistor (R shunt), a first end of the small value resistor (R cal) being connected to the other one of the input and output of the shunt resistor (R shunt), and a second end of the small value resistor (R cal) being connected to a second side of the switch (S 1); and in that the switch (S 1) is configured to be actuated by the microcontroller to selectively break the connection between its side of the shunt resistor (R shunt) and one of the first and second inputs of the amplifier such that the other side of the shunt resistor (R shunt) is connected to the other one of the first and second inputs of the amplifier as normal, and is also connected to the said one of the first and second inputs of the amplifier through the small value resistor (R cal).