The other side provides pass-through current for charging. I've been using it for several months with no problems. Update: In my Tesla Model 3, this doesn't seem to charge the iPhone on the power side of the plug. Power levels and/or connection type are not correctly registered. It charges other less demanding USB devices and powers a Qi charging pad that will replace a Qi-enabled iPhone. The solution still works for me because I charge my iPhone from a 12V outlet.
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