This hydrometer measures Specific Gravities in the range 1.1 to 1.3 (range given as 1100 to 1300).
It consists of a glass float weighted with lead shot that sits in a plastic cylinder, which has a large rubber bulb at the top end to allow the pipette to draw acid from a lead accumulator through the tube at the bottom end.
The SG reading indicates the charged state of the accumulator, around 1100 when flat, and around 1300 when fully charged. The scale is colour coded to indicate that the accumulator is GOOD FAIR or needs a RECHARGE.
The low reading indicates that sulphuric acid has been converted to Lead Sulphate on the electrodes. The accumulator needs to be charged as soon as possible to reverse the sulphating, and increase sulphuric acid SG to a higher value.
