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USB Port Output

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Here you go: Tesla Model S Fast Charging USB Port Hack - TESLARATI.com

Summary

I confirmed that both ports on my Model S charge at a rate of 1 amp, and not the 2.1/1 amp that some forum members (myself included) have previously reported. Actual measurements indicate that the PortaPow device is useless in the Model S. Skip it.
My recommendation is to get a good USB car charger that’s capable of charging at the maximum 2.1A rate. You can pick up a decent charger for under $20 that will actually do the job.
 
Here you go: Tesla Model S Fast Charging USB Port Hack - TESLARATI.com

Summary

I confirmed that both ports on my Model S charge at a rate of 1 amp, and not the 2.1/1 amp that some forum members (myself included) have previously reported. Actual measurements indicate that the PortaPow device is useless in the Model S. Skip it.
My recommendation is to get a good USB car charger that’s capable of charging at the maximum 2.1A rate. You can pick up a decent charger for under $20 that will actually do the job.

Awesome info! Thanks for the link. I ordered this yesterday: Amazon.com: Car Charger, [Apple MFI Certified] 3.1A Lightning iPhone Car Charger with 3ft Lightning Cable for iPhone 6s, 6 / 6 Plus / 5s / 5, iPad Air 2 and more by eBuddies (Black): Cell Phones Accessories
 
I know this is an ancient post, but wanted to report some findings I'm doing on my current loaner while my Model 3 is in the shop:

I had a rather janky setup but had the following equipment:
  • Drok USB Power Meter
  • Note 8
  • iPhone 7
  • Anker 10000 mah powerbank
  • A variety of USB cables and adaptor
  • 2018 Model S 75D
Plan on getting a proper USB3.0 extension cable so I can test the front USB ports properly. My existing set of adaptors/dongles causes too much voltage drop due to the increased resistance impacting the tests. I was unable to connect the evice directly to the front USB ports as well due to the shape of the tester. What I did find was the following:

  • Front USB seems to have a greater voltage drop than the rear USB
  • Rear USB can charge up to 1.5A on my powerbank, but all ports seem to limit to 1A on my both my phones
Front USB -
Vopen ~ 5.09
Vload ~ 4.5 to 4.75v (loose connection and or extension cable so...take these values with a grian of salt)
Max Current ~1 A with phone charging

Rear USB
Vopen ~5V
Vload ~4.9v
Max Current ~1 A with phone charging, ~1.5A charging powerbank directly. 1A with USB cord


Check out this dongle monstrosity :D in my attempt to get an working extension cord. Current dropped to a mere 0.3A at 4.5v due to the poor connection and reduced resistance.
USB Y-Splitter -> Mini to Micro USB dongle -> Micro to USB A dongle -> USB power meter -> USB A to USB C -> Note 8
20181203_004307.jpg
I had some other various USB extension cords but all them had some type of obstruction that prevented a proper connection.
 

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