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NEMA 5-15 v. 5-20 connector

Discussion in 'Model S: Battery & Charging' started by ljwobker, Mar 18, 2014.

  1. ljwobker

    ljwobker Geek.

    Nov 30, 2012
    Raleigh, NC
    Is there a sensible/safe way to only carry one connector (the 5-15, because it's compatible with infinitely more plugs) but manually adjust the charging current when plugged into a known 5-20 outlet?

    This would require that the 5-15 connector that Tesla provides is actually rated for 16A, which does not seem like a completely unreasonable assumption.
  2. Cosmacelf

    Cosmacelf Well-Known Member

    Mar 6, 2013
    San Diego
    Well, Tesla's 5-15 adapter will not allow you to adjust the charging current past 12A. So if you want to charge at 16A, and want to use Tesla's adapters, then you must buy the 5-20 adapter.

    Every Tesla adapter has a built in mechanism (a resistor, actually) that tells the car what the maximum charging current is.

    BTW, I have used my 5-20 adapter a number of times. It is very useful indeed when all you have is a 120V 5-20 plug. 33% more charge rate than the 5-15.

    You could, if you wanted to, build yourself a custom NEMA 14-50 to 5-15 adapter which would allow you to plug into any 5-15 or 5-20 plug and then manually set the charging current to 16A or whatever you thought was safe. Here's a document which outlines how to do this (and other things):
  3. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

    Jun 21, 2012
    And be sure to read the safety warnings in that document. :)

    The best solution is to purchase both adapters so that you can use them. In many cases a 15/20 amp conversion cord is worse than a 30 amp conversion cord because many "15A" receptacles are worn out and can barely handle a continuous load, much less a 12A load. I have seen a misguided individual (on another forum) use a conversion cord so that he could defeat the 80% continuous load requirement, and he melted a public outlet because he said "it's a 15 amp outlet, therefore I'm going to draw 15 amps".

    Keep it safe.
  4. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN 65513, Model 3: VIN 1913

    Jan 29, 2010
    Redwood Shores, CA
    Yes, the 5-20 adapter is worth it. I use it all the time to plugin at work and get upto 4.7 miles per hour of charging at 16A vs around 3.3-3.5 mph at 12A.

    I've tried using it at Chargepoint stations too - it's the backup outlet behind the door if the J1772 is taken already - but, those stations always trip if I were to attempt to draw 16A. Not sure why they bothered to make them 5-20 outlets if only 12A can be drawn from them.

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