Reverse currents

Hi,
I am setting up to characterize the charge/discharge performance of some LTO batteries for a client. To do this I need to insert the JS between the charger and load, and the battery. Charge current should be in the range of 200-500mA and a similar range for the load to discharge the battery during that test. I think I only need JS to accurately log either charge or discharge, however, my concern is if the magnitude of the reverse current is OK for JS.

What I plan on doing is setting up some automation to cycle the batteries between charge and discharge. I have no problem reconfiguring the JS connection when I need to change between charge and discharge characterization.

Does that sound OK?

This exercise also means I need to have JS sample the current at a low rate. I seem to remember reading about doing that, but cannot recall where. Any pointers would be much appreciated.

Should have read the manual first :frowning: It appears JS will be fine with the level of reverse current that may flow during testing.

Looks like I need to study pyjoulescope to understand the kind of logging I need to do. If you had a sample to help bootstrap the process that would be outstanding :slight_smile:

1 Like

Hi @SidPrice

Yes! As you noted, your Joulescope can measure in the reverse direction down to -1.5 A. While your Joulescope will autorange in the negative current direction, the super-fast hardware autoranging is only in the + direction. Autoranging on negative current overflow takes around 10 µs, which is typically more than fast enough for battery charging.

Check out the pyjoulescope_examples. If you are looking to record a JLS file, see capture_jls.py. If you only want the 2 Hz statistics data, then see statistics.py and trigger.py.

Hi @mliberty

Thanks for the links the examples look like a great starting point :slight_smile:

Hopefully they help! If you run into any issues or have questions, please feel free to post here or under a new topic.