multimeters of this sort cannot accurately measure such low voltages and amps since they by design inject low amounts of their own battery power into the system and measure what comes back.
multimeters of this sort cannot accurately measure such low voltages and amps
That's an interesting point. I've used similar multimeters for many years and was not aware of that limitation.
But for this particular design it would be trivial to determine both the voltage and the current to within about 1% accuracy.
V = I * R
Most of the voltage drop is across the 24 megohm resistor string. Measure the voltage across that, and you get the current flow, since you know the resistance is nominally 24,000,000 ohms. Most voltmeters have an impedance in the 1000+ megohm range, so measuring across the resistors won't introduce much inaccuracy.
The resistors themselves appear to be 5% tolerance. But by measuring the resistance of the string (open circuit) with the multimeter you should be able to determine their actual value to better than 1%.
