The ampere – hour meter or Amp Hr Meter or AH Meter is similar to the watt – hour meter which is used to calculate the total usage of electricity at households and commercial establishments. However, ampere – hour meter takes into account the ampere hours and just like the watt hour meter, it is also an integrating meter. In the typical sense, the ampere hour meters are similar to the digital current meter, just like the odometers which are present in your automobile. In this article, we attempt to understand the working mechanism and behind an ampere hour meter and its applications.
The most typical applications of Ampere Hour Meters in modern times have been in Electroplating, Battery Testing and Solar charging systems.
The plating thickness achieved in electroplating is directly proportional to the current flowing through the plating electrodes and the time for which this current flows. In older times, the current was kept reasonably constant and the time for which that current flows was noted. Integrating the current over the time gave an idea of the plating thickness. However, in practice, the current would vary with power fluctuations and changes in load leading to incorrect readings.
Modern day ampere hour meters, measure the instantaneous current and integrate the current over time for which it flows. Since the instantaneous current is being measured, the variations in current are automatically taken into account leading to a accurate measure of the plating thickness. This becomes increasingly important in precision electroplating applications like rhodium/platinum/gold electroplating where the cost of the plating is very high. Latest Ampere hour meters also help in automating systems where dosing pumps are used to add brighteners and other additives after every plating cycle using time relays on the AH meters which control the dosing and time for which the dosing is done.
Whenever we buy a battery, there is a voltage rating and in addition to that is an Ampere Hour rating known as the Ah rating of the battery. This defines the ability of the battery to supply the charge to the load at the rated voltage. Basically, it means that the battery will be able to supply current to the load for a certain period of time without its voltage level falling below its rated voltage.
In battery testing applications, a fully charged battery is discharged through a load. An Ampere Hour meter is connected in series with the load and the current is monitored. The current is integrated to calculate the Ampere Hour till the battery voltage falls below its rated value. This Ampere Hour represents the true AH of the battery.
Solar Charging Applications:
In solar and wind charging systems, the charge created by the solar cells and wind turbines are used to charge batteries. This stored charge is then used to run loads like fans, bulbs, motors etc.
In such systems, an Ampere Hour Meter is used to monitor the charging AH and the discharging AH of the battery. This helps for users to know the current status of the batteries and the charge currently available. Such systems also help to automate systems where a generator set may be used to charge the battery in case the AH level of the battery falls below a certain level.
Modern day Ampere Hour meters integrate a host of additional features like displaying voltage & current and control output relays for monitoring and controlling the AH application for which it is used. They may also offer logging facilities for AH being measured.