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IGN-ON - Is HV Battery connected?

Discussion in 'Gen 3 Prius Technical Discussion' started by jdcollins5, Jun 27, 2010.

  1. jdcollins5

    jdcollins5 Senior Member

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    I have searched through several threads and have found conflicting opinions on this question.

    Can someone verify whether in the IGN-ON mode the HV battery is connected and recharges the 12V battery through the DC-DC converter or not?
     
    #1 jdcollins5, Jun 27, 2010
  2. dogfriend

    dogfriend Human - Animal Hybrid

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    No, the battery main relay(s) are only closed (connected) when the car is in Ready. Not in ACC, Not in IGN-On, only in Ready.
     
    #2 dogfriend, Jun 27, 2010
  3. jdcollins5

    jdcollins5 Senior Member

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    Dogfriend,

    Thanks. I had read this multiple times that it is better to leave your car in IGN-ON when listening to radio, etc., since the HV battery will keep the 12V battery recharged.

    I repeated this in another thread and Mike Dimmick said this was not true. I wanted to make sure I was not repeating any misinformation.

    So, if you are going to listen to the radio or run any other accessories for any length of time you need to keep the car in Ready so the HV batteries are connected and the ICE can recharge HV batteries when necessary?

    Dwight
     
    #3 jdcollins5, Jun 28, 2010
  4. dogfriend

    dogfriend Human - Animal Hybrid

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    Yes, if you are going to use accessories for a long period of time, Ready mode will allow the 12v buss (and 12v battery) to be powered by the HV battery via the DC to DC converter.

    IMO, the purpose of the 3 modes:

    ACC is for short term use of the Audio system or the NAV, but higher power items (e.g. the AC fan) are not powered. On the Gen 2 cars, ACC will automatically shut off after 1 hour of use to help preserve the 12v battery.

    IG-On is really for troubleshooting purposes - all of the 12v actuators and sensors on the engine are powered, the warning lights on the dash are lit, the AC fan (but not the HV powered compressor) is on. Don't use IG-On for a long period of time, this will run down the 12v battery rapidly.

    Ready is when the hybrid system is active - the system main relays close (first the neg side, then the positive with a resistor in series to limit the start up current spike, then a second positive switches in while the first positive switches out). You can hear the clicking back in the battery area as the relays close. When in Ready, the HV battery powers the 12v buss, the AC compressor and fan are powered and of course the ICE can come on as needed to charge the HV battery as it gets depleted.
     
    #4 dogfriend, Jun 28, 2010
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  5. qbee42

    qbee42 My other car is a boat

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    Correct. Ready is the only state that will keep the 12V battery charged. Make sure to sit in Park, not N. In N the engine will not charge the HV battery.

    Tom
     
    #5 qbee42, Jun 28, 2010
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