Seeking USB-C PD breakout board suggestions - Page 1
Forum section: electronics / general

author: Rasterist
author_rank: Contributor
timestamp: October 19, 2024, 08:55:12 pm
content: I need to create a load on a 100W USB-C PD port (to periodically discharge a portable power station). I'd like to just connect a power resistor to a USB-C PD breakout board, but all the boards I'm finding either top out at 2A or don't specify their limit. Can anyone recommend one that will handle 100W? I won't go that high, more like 20W - 50W, but I'd like the margin. Thanks for any pointers.

author: nctnico
author_rank: Super Contributor
timestamp: October 19, 2024, 09:17:32 pm
content: Is this for long term use? If this is for experimentation, it is safe to assume the USB-C connectors are rated for 5A as this is what they are supposed to be rated for by the standards.

author: Rasterist
author_rank: Contributor
timestamp: October 19, 2024, 10:08:58 pm
content: I'm working on a system that will discharge/recharge the power station every three months, to preserve battery health, so long-term (though each discharge cycle should take 2 - 3 days). The specs claim the USB-C port is rated at 100W, so I figured I'd configure a USB-C trigger board for 20V and draw 2.5A or so.

author: nctnico
author_rank: Super Contributor
timestamp: October 19, 2024, 10:13:49 pm
content: I'd keep the battery between 50% and 70% as this is the best charge level for Li-ion batteries when stored. Charging & discharging means wear so I wouldn't recommend doing that. Assuming your system uses some kind of Li-ion batteries.

author: Rasterist
author_rank: Contributor
timestamp: October 19, 2024, 10:21:47 pm
content: The chemistry is LiFePO4 and it's recommended to store them at 60%. The charging level is user-programmable, so I'm planning on using a timer that will just charge a little longer (maybe 2X) than it takes to reach that level from 0%. I'll need another timer, though, to switch in the load for a period predetermined to fully discharge the battery. This is the load I'm trying to find a PD board for.

author: shabaz
author_rank: Frequent Contributor
timestamp: October 19, 2024, 11:38:00 pm
content: By USB-C PD Breakout, I couldn't tell if you meant a USB-C connector breakout, or a board with PD sink capability on it.If the latter, there's aMikroE STUSB4500 Sink "Click"board. It's easy to connect up to (say) aPi Picoand then send I2C instructions to it.It's not the easiest chip to control unfortunately. However I wrote somePython code for itthat can be used withThonny software(to use, followinstructions on the raspberrypi website to install MicroPython, and then use Thonny to upload the Python code, and Thonny has a command prompt where you can then control things by issuing instructions as shown in the screenshot.Code:Connections:Sink Click Pi PicoSDA GPIO4SCL GPIO5INT(Alert) GPIO15RST GPIO143V3 3.3VGND GNDI ran a quick test to see if I could reach 100W.The other screenshots show the crude testbed, and I was able to get 93W out of that board (I didn't particularly try harder, there will be some loss in the cables. I also only ran this for a few minutes just to grab the photos, and I've not checked the MOSFET specs on that Click board.Is this something along the lines of what you're looking for?

author: Rasterist
author_rank: Contributor
timestamp: October 20, 2024, 12:06:37 am
content: Thanks, shabaz. I really appreciate the effort. While that result would technically work, it's more effort and complexity (and, possibly, less reliability) than what I had in mind. I don't need the sink capability on the PD board, just a couple of pads I can solder a power resistor to. So a basic trigger board should suffice, as long as it's able to dissipate ~100W.