Ampere-Hour Meter:

An ampere-hour  meter  registers  ampere-hours  and  is  an  integrating  meter  same  to  the watt-hour meter used to measure electricity usage in a home.  Classical ampere-hour meters are digital indicators same to the odometer used in automobiles.  An ampere-hour meter is a direct current meter which will register in either direction depending on the direction of current flow.  For instance, beginning from a produced reading, that will register the amount of discharge of a battery; while the battery is placed on charge that will operate in the opposite direction, returning once again to its beginning point.   While this point is reached, the battery has received a charge equivalent to the discharge, and the charge is stopped.  It is generally desired to provide a battery a 10 percent overcharge. This is accomplished through designing the ampere-hour meter to run 10 percent slow in the charge direction.   Those meters are subject to inaccuracies and cannot record the internal losses of a battery.   That attempt to follow the charge and discharge, but inherently do not denotes the correct state of charge.  Same to an ammeter, the ampere-hour meter is linked in series. While the ampere-hour meters were used quite extensively in the earlier, they have been largely superseded through the voltage-time method of control.