Hi,
Recently, I attempted to use the ADALM1000 (M1K) to discharge Ni-MH batteries and obtain their discharge curves.
The experiment setup was very simple: I connected the battery’s positive terminal (Bat+) to CHA and the negative terminal (Bat-) to GND, without any limiting resistor in between.
However, I encountered an issue where the discharge process seems to stop when the battery voltage drops to approximately 1.23V. The battery I used was a Panasonic Eneloop AA size Ni-MH battery with a nominal capacity of 1900mAh. As you can see in the attached data, when I was using a -200mA discharge current to sink the battery, the datalogger logged samples once per second. The discharge curve ran for about 18 hours (65485 seconds), which is obviously much longer than the expected duration based on the nominal capacity.
My goal is to fully discharge the Ni-MH batteries to understand their complete discharge characteristics. I understand that the current sink loop circuit should not be able to sink the voltage to near 0V, as there seems to be a load resistor of about 4 ohms, which would drop about 0.8V at -200mA.
I wonder if there is any way to achieve this goal? There are hardly any similar applications available. I only found one example, “Active Electronic Loads,” but it seems not set up for low voltage applications.
Any suggestions would be much appreciated.
Thanks,
Calvin
