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15A dedicated circuit

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by fberger, Nov 7, 2011.

  1. fberger

    fberger Junior Member

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    I am not an electrician and am trying to determine if I will be able to recharge my plugin Prius in my garage without additional wiring work.

    I recently connected a compressor to the outlet I had reserved for the PIP. The compressor's manual stated a requirement for a 15A circuit. Unfortuantely the compressor was not able to pull enough power to start. I ran an extension cord to a new outlet in the house that I knew for sure was connected to a 20A circuit breaker. The compressor worked fine from there.

    So my question is this: will the Prius still charge off of that weak outlet in the garage, just take longer than the 3 hours published, or will it completely fail like the compressor did until I connect it to a true dedicated 15A circuit?
     
    #1 fberger, Nov 7, 2011
  2. ClaySacramento

    ClaySacramento Junior Member

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    If your 15A circuit breaker was tripping when you attempted to power on the compressor which called for a 15A circuit, then its possible the same thing will happen when you connect your Plug-in Prius. If the circuit breaker was not tripping, yet the compressor would not start, then I'd suggest testing that outlet with some other devices to make sure its functioning correctly.

     
    #2 ClaySacramento, Nov 7, 2011
  3. qbee42

    qbee42 My other car is a boat

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    When you say that the compressor could not pull enough power to start, do you mean that the compressor tripped the circuit protection, or that voltage drop caused the compressor to stall?

    If the latter, you have a serious wiring problem. There is absolutely no way that a normal extension cord will have less voltage drop than 14 or 12 gauge house wiring.

    If the former, keep in mind that compressors require a lot of power to start, after which power demand drops. This is typical of electric motors, particularly those starting against a load. I would expect a charger to have softer starting characteristics.

    Tom
     
    #3 qbee42, Nov 7, 2011
  4. fberger

    fberger Junior Member

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    Sounds like I may have a wiring issue in my garage, the circuit breaker did not trip there when I had the compressor connected to it. The compressor would struggle for 30 seconds, then its internal circuit breaker would trip. I will also test without the extension cord to make sure it is an outlet issue. The weird thing is, when I used a different outlet with the same extension cord, it worked fine.

    So coming back to the charger in the Prius, if it gets connected to an outlet that is on a shared circuit, the breaker will trip, not just charge slower, correct? It is an "all or nothing" situation, and not a matter of duration to charge when Toyota says 3hours on a 15 Amp circuit. I guess voltage variations will change the time it takes to charge, not the amps.
     
    #4 fberger, Nov 7, 2011
  5. greenleaf

    greenleaf Member

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    It sounds like you have a larger than expected voltage drop in the 15A circuit when a large current is drawn.

    If I recall correctly, the EVSE unit from Toyota is expected to draw 12A. Whether it will work or not really depends on the circuitry implemented in the unit. If it does work, it will take longer to charge.

    Let's consider some numbers. The nominal voltage at your panel should be 120V. I suspect that from your description with the compressor (say 12A current), the voltage available at your compressor is 100V. That means about 20% is lost heating up the wire and/or at some loose electrical contact. If you attempt to charge with this outlet, it will take you 20% longer.

    Safety-wise, I recommend that you get the circuit checked, because the 20% (almost 20x12 = 240W) lost as heat somewhere would potentially catch a fire.

    PS. Since Japan runs on 100V, the EVSE might work if it is designed to be used in Japan and in the US. Just a guess.
     
    #5 greenleaf, Nov 7, 2011
  6. gwmort

    gwmort Active Member

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    Don't know what the Toyota unit is like, but the EVSE that comes with the Volt has a slower charge rate setting to manually lower your amp draw when in similar situations.
     
    #6 gwmort, Nov 7, 2011
  7. hill

    hill High Fiber Member

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    Is he talking 120v or 240v ??
     
    #7 hill, Nov 8, 2011
  8. fberger

    fberger Junior Member

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    I did more testing with my compressor connected directly to the outlet in my garage, without using any extension cord. The problem has completely disappeared.

    Lesson learned for me: when the manual says to use a certain gauge for the extension cord, it is wise to follow the instructions and purchase a better cord;)

    When I receive my new Plugin Prius, I will make sure I get a decent extension cord if the one supplied with the charger is too short.

    Thanks all for your expert advice!
     
    #8 fberger, Nov 8, 2011
  9. mgb4tim

    mgb4tim Noob

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    oh yeah, the extension cord will kill you. I had a radial arm saw that took a few seconds to get up to speed with a cord. Ran a new 20A circuit on 12ga wire, kicked over instantly.
     
    #9 mgb4tim, Nov 8, 2011
  10. qbee42

    qbee42 My other car is a boat

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    You should have stated in the OP that you were using an extension cord for both test cases. When I read your post I assumed you were plugging in directly in the garage, but using an extension cord to get to the house.

    It's no wonder you had trouble, combining an extension cord with the long wiring run to the garage.

    Tom
     
    #10 qbee42, Nov 9, 2011
  11. fberger

    fberger Junior Member

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    Sorry Tom, you are right. I was not clear enough. I did not know at the time of posting that the extension cord could make a difference, and by not stating it I left out a key piece of information that would have been helpful.
     
    #11 fberger, Nov 9, 2011
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