Antique Battery Tester Restoration

This time I'm restoring an antique battery tester, used to measure the current in early car battery .

Why no final test ?
The early car batteries was 6V and made of 3x 2V cells ( you ca see it in the video a 0.20min)
The device is designed to measure current in each cell.
The wire beteween the two leads act as a resistor to simulate a load in the cell tho ensure that the cell will deliver 2V at the required amperage.
But if you connect the tester to a DC power supply, the wire will create a short circuit.
As the original batteries are no longer produced since decades, I can't do a proper test of the device.
Hope you still enjoyed the video and thanks fort watching.