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12V 120w Socket

Discussion in 'Gen 3 Prius Technical Discussion' started by AnneN, May 23, 2024.

  1. AnneN

    AnneN Junior Member

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    Hi.

    If I were to plug in 2 separate accessories into the 12V 120w socket, using a socket adapter, and the total draw exceeded the 120, say 160w, would a fuse blow?
    Would I damage the accessories? Damage the electrical system?
    Or would the socket just shut off the power to one of the sockets to bring it back to 120w?

    I have a small power generator that will charge when driving taking approx 110w and a cooler box taking 50w.
    I assume running one directly from the 12v battery via an added 12v cable and one from the built-in 12v socket would be the same as it is the accumulated draw on the system?
    Thank you
     
    #1 AnneN, May 23, 2024
  2. rjparker

    rjparker Tu Humilde Sirviente

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    You would blow a fuse in the car when using a two to one adapter and drawing 160w. Otherwise no damage.

    Wiring something separately to the battery has the real possibility of discharging the 12v battery to the point the car won't start and or the 12v battery has to be replaced. However the 120w limit of the power outlet is no longer an issue. To avoid possible battery discharge a quality battery isolator is recommended. Those are sold as rv vehicle accessories.

    The battery discharge issue is excessive parasitic draw of battery power when the car is off. An experienced mechanic could check for that after wiring in your aftermarket portable storage but aftermarket devices can behave one time and discharge your 12v battery another time. A quality battery isolator with 5ma or less parasitic draw is recommended.
     
    #2 rjparker, May 23, 2024
    Last edited: May 23, 2024
  3. AnneN

    AnneN Junior Member

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    Thank you.

    I would not be leaving the small power station permanently wired to the 12v battery. I have a 14 awg wired connector, eyelets one end to battery and male barrel connector the other end that plugs into the generator as needed.

    I know there is a chance of parasitic draw, I'm keeping an eye on the battery level, before starting and whilst driving, seems OK but it is such a small battery I know it could go flat very fast. I have a Noco Genius in the car for an emergency!

    The isolator is a good idea. Will look for one with the 5ma spec.

    I'm still not 100% sure about if I can charge more than 120w if I'm running one item directly from the battery and another from the in-car 12v port whilst the car is running/ready mode. Can it be done without causing damage or is it 120w total from all sources?
    Thanks again.
     
    #3 AnneN, May 23, 2024
  4. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Might be worth re-checking this. I'm assuming that "power generator" means a portable battery bank in this context.

    A battery bank that draws 110W during charging is not one that I would characterize as "small," which makes me wonder if there's been an error in reading the specs.

    The 120W limit applies to the fuse feeding the receptacle. The car can offer something like ~750W to the collective sum of all accessories, just not all through that one port.

    Thus if you direct-connect one of those loads to the car's native 12v battery, you'll have the full 120W budget available to the lighter plug.
     
    #4 Leadfoot J. McCoalroller, May 23, 2024
    Last edited: May 23, 2024
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  5. AnneN

    AnneN Junior Member

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    Thank you, this is very helpful, makes sense to my simple brain!

    The battery bank is a solar generator type bank, its an Allpowers R600.

    I now feel safe/happy that i can plug the battery generator into either the car port or the battery port and the cooler at the same time in the opposite port. I'm glad I didn't plug them both in to the car port via the adapter at the same time and blow the fuse!

    Your help is much appreciated.
    All the best.
     
    #5 AnneN, May 23, 2024
  6. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I took a look. From what I can see that thing can pull quite a lot in fast-charge mode, so you are on the right track to separate these loads.
     
    #6 Leadfoot J. McCoalroller, May 23, 2024
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  7. ChapmanF

    ChapmanF Senior Member

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    More precisely, the car has a "DC/DC converter" that is able to supply around 1500 watts gross—including the power the car itself has to use. How much power the car itself uses will vary. When the car is sitting quietly in Park and is READY, it only uses about 400 watts, leaving a capacity as high as 1100 watts for you. When you have some of the hungrier accessories like the heat and defoggers and wipers and such in use, there is less left over for you. Under some circumstances when a lot of the car's own loads are in use (say the electric supplemental heat is on and you make a turn in a parking lot, heavy on the power steering assist), there may be nothing left for you—Toyota had little incentive to oversize the converter beyond the car's own possible combination of needs.

    Exceeding the converter's maximum output on occasion probably does no lasting damage; its output voltage may begin to drop a little first, and under a prolonged overload it may shut off.
     
    #7 ChapmanF, May 23, 2024
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  8. rjparker

    rjparker Tu Humilde Sirviente

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    Yes.

    An isolator can save your battery by automatically disconnecting your 110w load. If you direct connect the extra load and forget to disconnect a couple of times your 12v battery can be damaged. Maybe not the first or second time but…
     
    #8 rjparker, May 23, 2024
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  9. AnneN

    AnneN Junior Member

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    The max I've seen it pull when charging through the 12v connector is 113w. If it's plugged into AC then it goes to around 330w. I also have 200w solar panels that I use if I'm parked up on a sunny day. I'm thinking of putting in a 1000w pure sine wave inverter so I have another, faster, option when on the road.
     
    #9 AnneN, May 23, 2024
  10. AnneN

    AnneN Junior Member

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    Thank you. Really helpful information.
     
    #10 AnneN, May 23, 2024
  11. AnneN

    AnneN Junior Member

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    Completely agree. By the law of averages I am bound to walk away from the car without manually unplugging the equipment and totally kill the battery.
     
    #11 AnneN, May 23, 2024
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