How to discharge a battery onto a load with constant voltage/current while battery output voltage decreases.

Hi, I am looking for a solution to discharge a battery. I want the battery to be constantly applying 300w to a load, even as the battery discharges and is reducing its output voltage. Would a buck dc-dc converter give a constant voltage/ current output?

Answer 1

[Xiangchun]

Hi Cathal,

To maintain a constant discharge power from the battery, it would be necessary to increase discharge current progressively as voltage decreases during discharge. A closed-loop feedback control would be needed to adjust the current for maintaining a constant power.

Best wishes,

Xiangchun

[SALAH alatai]

@Xiangchun if possible please share a demo or any reference to describe more of closed-loop feedback control to adjust the current for maintaining a constant power. thanks

[Xiangchun]

@SALAH alatai.

Hi Salah, here is an example which contains a closed-loop feedback control to maintain a constant voltage by changing the charge current. It can be easily modified to maintain a constant power (i.e. current times voltage).

Smartphone Battery Charging - MATLAB & Simulink (mathworks.com)

Best,

Xiangchun

[SALAH alatai]

@Xiangchun thanks for the response. This model has been built by the foundation library (blue lines) and I am working with a specialized library (black lines), much different even the battery and the powergiu block.