This circuit can measure the capacity of individual cells as well as battery packs with an open circuit voltage of up to 35 V. The only requirement is that the discharged cell voltage has to be between 0.5 V and 2.5 V. During the discharge period, the instantaneous voltage is measured at one minute intervals and stored in memory. This allows the voltage curve to be drawn once the discharge process is completed.As can be seen from the title photograph, the appearance of the battery discharger is simple and clearly arranged. There is a small keyboard with 12 keys for the input of data. All information is displayed on a 16-character LCD. The battery is connected to the two instrument terminals, a black one and a red one. In addition there are two slide switches, one is for on/off, the other one we will describe later. On the back is a sizeable heatsink onto which the discharge transistor is mounted. There are also eight large holes in the front panel, because the enclosure contains a cooling fan that blows air over the heatsink during the discharge period. This allows the power dissipation capacity to be nearly doubled.