Charging via extension cord?

Discussion in 'Clarity' started by Fast Eddie B, Nov 22, 2018.

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  1. This is clearly something Honda frowns upon for 110v charging.

    One of several such warnings:


    Clearly, the “Most Conservative Action” is to adhere to such warnings, and I’m not suggesting otherwise.

    But if the extension cord is of high quality and sufficient wire size (12 ga?), I’m not sure how it’s fundamentally different from the same sized ROMEX that carries current to remote outlets anyway.

    I can imagine lots of scenarios where Honda’s charging cable would literally come up short, mainly at friend’s homes while traveling.

    Any thoughts on this? I did do a search, but didn’t come up with any discussions specific to this topic.
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  3. Robert_Alabama

    Robert_Alabama Well-Known Member

    I've never had any problems using an extension cord as long as it is rated for at least 16A. The longer the cord, the higher the amp rating I would want just to limit losses.
  4. craze1cars

    craze1cars Well-Known Member

    Extension cord works fine (subject to all the disclaimers n my last paragraph below.) Just go heavy gauge. 12 is fine. I have actually charged with a PAIR of 16s about 75 feet long total, linked together, and the car charged with no damage. The cords and plugs got rather warm and their life was certainly shortened, but they did not get super hot and didn’t melt. NOT RECOMMENDED but it worked as an experiment for me under some regular supervision while drinking a beer in the garage with my brother, chuckling and discussing the finer details of how wrong this was, to ensure no smoke and excessive heat ensued. If you understand wire gauges and electricity, extension cord use is safe. Recognize the car and charger doesn’t know the difference and it will charge right up to the point the cord melts, shorts, arcs, and burns your house down if necessary. So the warning as written by Honda is valid, and written for the vast majority of humans who do not understand extension cords and electricity. Such people WILL burn down a building somewhere, someday. There is a real risk of fire if you err.

    I say if you carry a non-abused, fully uncoiled, 25 foot, 12 gauge (10 is even better), with clean shiny contacts, and check it end to end for heat after the first 10 minute of charging every time you use it, and understand the risk, you’re good to go and very safe. And if you don’t understand exactly why I specifically said ALL 7 of those qualifiers, you absolutely should NOT use extension cords.
    Last edited: Nov 22, 2018
    Jan likes this.
  5. petteyg359

    petteyg359 Well-Known Member

    Again, 10 ga is ridiculously beyond overkill at 25'. 12 ga at 25' is still overkill. A 100' 12ga cord never gets warm on a 14 A corded lawnmower. Yes, that's not the 12+ hours the car takes to charge on 120 V, but resistance is not an over-time function. If any generated heat is immediately dissipated from the cable and plugs for the two hours it takes to mow, the same heat is immediately dissipated from the cable and plugs for the X hours it is being used to charge the car.
    Last edited: Nov 22, 2018
  6. Vezz66

    Vezz66 Member

    I got the Amazon Basics 12 gauge 50 footer for summer charging at the cottage, which is fine up to 15 amps.

    Agree 14 gauge is fine for 25 feet.
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  8. craze1cars

    craze1cars Well-Known Member

    Agree with all. I’m a big fan of overkill when it comes to electrical and will always spend another $10 or $15 to get a little cushion and to assist the aging process that occurs with extension cord handling over time. If you understand electricity, go lighter.
    Daniel M W likes this.
  9. jdonalds

    jdonalds Well-Known Member

    I used an extension cord plugged into a shared 120V outlet in the garage for weeks until my Level 2 charge station was installed. No problems.
  10. Tangible

    Tangible Active Member

    Romex is solid wire; extension cords are stranded. Big difference in capacity.
  11. Fair cop.

    I should have said the same capacity ROMEX. Or maybe rated.

    But curious, what is the difference in current-carrying capability of 12 ga solid and 12 ga stranded wire?

    Edited to add: a quick Google search seems to say it’s not a given that solid has more capacity than stranded given the same diameter.
    Last edited: Nov 25, 2018
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  13. MNSteve

    MNSteve Well-Known Member

  14. Tangible

    Tangible Active Member

    It looks like I was wrong. There’s no evidence that, for a given gauge, solid wire has more capacity than stranded.
  15. For now, I found 2 short, heavy duty appliance extension cords in my garage.

    At our new home, there’s an appropriate outlet by the door on our porch for charging the Clarity in the nearest carport spot. But the stock cable comes up short. A single short extension cord bridges the gap:


    I’ll probably spring for a 25’ 12ga extension from Amazon in the near future for traveling, but these will do for now.
  16. J2K111

    J2K111 New Member

    An extension cord, any cord really, will act as a resistor and create some voltage drop (V_out < 120V). Short and thick cable will be your best bet. If it needs to be longer (>25ft) go as thick as possible (8, 10, 12 AWG).

    In general, they put those warnings in for the dopes that think all extension cords are the same. Don't be one of those dopes...

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