Sticky FAQ about Bad #USB   #TypeC   Legacy cables:

Thanks to +Mike Trieu for the suggestion.

Q : Why is a bad 3A resistor a problem?
A: 3A is bad because all of these cables and adapters are legacy host port adapter cable, meaning the other end of the cable is Type-A plug. The Type-A port and the vast majority of the devices that have Type-A ports were never designed to support 3A charging.

The cable lies to the phone by telling the phone it's attached to a pure 3A charging path, like the C-to-C cable to the OEM 3A charger that ships with the Nexus 6P/5X. The phone will attempt to draw 3A, but that may damage the weaker device you have the Type-A end of the cable plugged into.

Q: If I have a 1A or 2A charger, am I safe?
No, if you have a weaker charger, you are actually at MORE risk because your phone/tablet/laptop may not know to stop at the 1A or 2A limit the charger advertises because of the improper identifier in the cable.

Q: Do C to C cables have the same problem?
No. C to C cables do not have the same problem because they are required to be straight pass through and do not have a pullup built into the cable. If the other end of the cable is Type-C, then as long as you plug into a 3A charger (like the one you get with Nexus phones), you will get fast charging in a safe way.

Q: Can you recommend a Type-A charger? Is <insert some random Type-A charger from Amazon> safe? Is it fast?
I cannot review every charger, but as long as you have a safe compliant cable with a 56kΩ resistor, the phone will limit itself to safe levels of charging for Type-A chargers and hubs.

Whether or not a particular charger works best for your phone in terms of charge speed I cannot say definitively. It really depends on a ton of factors, including the protocols your phone and the charger supports. Phones and charger may be able to support up to 2.4A using various proprietary protocols with a safe cable.

Q: Can you recommend a Type-C fast charger?
I like the Google one. 2 Type-C ports, 22.5W total power.
https://store.google.com/product/usb_c_dual_port_charger

If you want a SUPER deluxe one, get the Pixel 2's charger. It will support up to 60W charging using USB PD. Fast charge your laptop. :)
https://store.google.com/product/universal_type_c_60w_charger

Q: How can I test the cable myself?
If you have a Chromebook Pixel :
https://plus.google.com/+BensonLeung/posts/jGP5249NppF

If you have a Nexus 6P/5X phone :
https://plus.google.com/+GeoffHoff/posts/eMsr1cyw75s

Or use CheckR:
https://play.google.com/store/apps/details?id=net.mderezynski.checkr

Q: I want to keep my bad cable. Is that OK?
Be very careful what you plug it into. If you must keep it, tag the cable with a label that says "3A bad cable" or something so that in a few years when you forget about this controversy, you don't grab that cable and damage a charger accidentally.

Q: Where can I find the USB spec to read up on this more?
http://www.usb.org/developers/usbtypec
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