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Can the Roadster charge from DC?

Discussion in 'Roadster: Technical' started by SteveWest, Jul 12, 2013.

  1. SteveWest

    SteveWest 2012 Roadster 2.5, 2014 P85+, 2015 P85D

    Joined:
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    Location:
    New Zealand
    Has anyone tried connecting DC power to the AC input pins on a Roadster?

    Of course it's not officially supported, but I'm curious if the charger would cope. I'm hopeful that it could, since many typical Switchmode Power Supplies can accept a high voltage DC input.

    I recently brodered my Roadster 5km from home, and it would be nice to have the option of charging @ 70A from a portable rescue battery, say 10 - 15 kWh worth.

    Cheers, Steve
     
  2. wycolo

    wycolo Active Member

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    #2 wycolo, Jul 12, 2013
    Last edited: Jul 12, 2013
    If you can haul a dozen+ big lead acid batts to the site why not just use this vehicle to tow the R home? The R rolls easily but you would need 2nd human to accomplish this.

    In a few days I'll be receiving the newest/biggest Honda EU Inverter Generator, rated 6500 watts (5500 watts continuous). This will provide 20A+ @240v to charge R or S, so a relatively 'fast' recovery. At 250 pounds this unit would trailer nicely, so you could bring along your own rescue apparatus on Road Trips.
    --
     
  3. dhrivnak

    dhrivnak Active Member

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    I would be very hesitant to try this without some detailed knowledge. On some EV conversions I tried to use some AC relays that were 5X oversized and I destroyed them with DC. DC is much harder on contactors and relays as there is no 0 point and there is noticeable arcing that destroyed the components.
     
  4. Raffy.Roma

    Raffy.Roma Active Member

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    I don't think it would even work to connect DC power to AC input. The AC input only accepts alternate voltage which is then converted to DC. If somebody would like to try to connect DC power to a Roadster should bypass the AC input and get directly the internal DC input of the Roadster I think.
    Does anybody know how to do this?
     
  5. Doug_G

    Doug_G Lead Moderator

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    Almost certainly Roadster is directly chopping the incoming AC power to make internal DC power, and this will happen inside the PEM. Essentially it's a huge version of the switching power supply you have in your desktop PC.

    The car is designed for AC input. If you are lucky (actually this is very likely) the PEM will realize the power is no good and refuse to connect. If you are unlucky then you will destroy the PEM and maybe more. A replacement PEM costs many thousands.

    Do NOT do this! Stick to the rated input specifications!!!
     

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