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HV to 12v dc-dc converter operation when powered off

Discussion in 'Gen 2 Prius Technical Discussion' started by partipilo, Oct 27, 2007.

  1. partipilo

    partipilo Weirdo

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    Let's say it was possible to hack the system in a fashion that I could pull power from the 12v battery while the car was powered off; say, to run a thermoelectric cooler in the trunk for example. Will the system still run the dc-dc converter to charge the 12v from the HV pack when the car is turned off?
     
    #1 partipilo, Oct 27, 2007
  2. efusco

    efusco Moderator Emeritus
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    Nope, the relay is completely disconnected unless you're in READY mode. I suppose that could be hacked too, but that seems like a good way to drain and ruin the HV battery.
     
    #2 efusco, Oct 27, 2007
  3. Danny Hamilton

    Danny Hamilton Active Member

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    <div class='quotetop'>QUOTE(partipilo @ Oct 27 2007, 07:43 AM) [snapback]531138[/snapback]</div>
    Drawing power off the 12V battery when the system is off is easy. The battery is right there in the "trunk". Just connect the leads to the terminals on the battery.

    Unfortunately, when the car is "off" a relay completely disconnects the HV pack from the inverter. Unless you are planning on messing around with the HV system and bypassing that relay, that power isn't accessible while the car is off. Also the 12V battery in the Prius is smaller (less power) than the typical non hybrid car, so it doesn't take nearly as much to drain it. Once it is dead, you'll need a jump to turn the car on. It's the 12V system that boots up the car and closes the relay to the HV.

    Now if you do tap directly into the HV pack, be aware that you could potentially draw the power down too far (since the car won't be on it won't be recharging the batter for you). If it gets down too far, it won't be able to turn the ICE over to start it up (the HV is used to start the ICE not the 12V). If the ICE won't start up, you don't have a way of recharging the HV unless you are going to buy or build a recharger for it.
     
    #3 Danny Hamilton, Oct 27, 2007
  4. patsparks

    patsparks An Aussie perspective

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    Safer to get a portable battery pack, Waeco sell one just for running fridges!

    Edit, This is what I was taling about
    [​IMG]
    It seems it has been discontinued.
     
    #4 patsparks, Oct 27, 2007
  5. qbee42

    qbee42 My other car is a boat

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    You can also leave the Prius running. It will run the ICE as necessary to charge the HV battery, and the inverter will power the 12V device. People have done this to run portions of their homes in a major power failure.

    Tom
     
    #5 qbee42, Oct 27, 2007
  6. partipilo

    partipilo Weirdo

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    <div class='quotetop'>QUOTE(qbee42 @ Oct 27 2007, 10:38 AM) [snapback]531190[/snapback]</div>
    This is another thing I have considered, reading various threads etc etc... The question I have then is, how many of you have done this, and had parking enforcement issue a ticket for a running vehicle, even if you used the mechanical key to lock the car with it powered on?
     
    #6 partipilo, Oct 29, 2007
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