With the ever increasing demand for deep cycle batteries, suppliers need to be able to confirm if the battery has indeed got the specified capacity. Battery capacity is typically expressed in Amp hours (Ah), but it can also be specified in Watt hours. To test the capacity, the battery needs to be discharged at a constant current, it can not be measured by loading the battery with a resistor.

The discharge process needs to be stopped at a set minimum voltage to prevent permanent damage to the battery.

This instrument does it all and stores the data in CSV format to a standard SD card. Plug the card in your computer and after a few mouse clicks, EXCEL will provide you a smart looking graph. 

The discharge current can be set between 1A and 20A. A model of 30A is also available.

As an additional feature, the instrument offers a quick crank test. Download the pdf datasheet to get all the information.

Discharge curves plotted in Excel

This graph shows discharge curves at different currents of deep cycle batteries which were specified to be 200Ah. The tests were performed on a battery age of only 2 years old.

The fact that the voltage dropped so fast in the beginning shows a relatively high internal resistance.