alt Hacker NewsSimilarly: Is there a USB-C power delivery adapter to force directionality? I needed to siphon off power from small batteries into a larger pack (that could supply more power out than the small packs) in a power outage. I absolutely could not force my larger power station to accept a charge and it kept pushing power back the wrong direction despite which ends of the cable I plugged in first.
It's ugly, but yes: https://www.anker.com/products/a8895?variant=45839927509142
That cable has one power input (that is only an input), and two outputs (that are only outputs), and a brainbox in the middle to direct the circus.
If we label the connectors as A, B, and C, then it works like this: A charges B and/or C, and other charging directions are no-op.
The less-complex way is to use a USB A to C cable, if that's appropriate. With these, the A side is always the source and the C side is always the sink.
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And yeah, it's annoying. I got a cheap lithium car jump starter several years ago with some neat power bank features (like 60W USB PD in/out, on one port). So I plugged it into my phone with USB C at my desk, and discovered that they'd charge eachother seemingly randomly. While changing nothing, I'd look over and sometimes the jump starter would charge the phone, and sometimes the phone would be charging the jump starter. The conglomeration formed a heater, with more steps.
(Back and forth with the same poop, forever.)