Silent A/C camping with external power supply?

Discussion in 'Gen 2 Prius Main Forum' started by pc85, Apr 7, 2019.

  1. pc85

    pc85 New Member

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    I have some experience camping in Prius and running A/C and heat throughout the night. As many know, the engine turns on for about 30 seconds maybe every half hour or so, maintaining a given temperature.

    If parked in a high-traffic area, this could 'blow your cover' while stealth camping. It also might occasionally cause you to wake up, though that wasn't an issue for me. As good as the feature is, eliminating the engine turn-on somehow would definitely be an improvement.

    Question: if one were to connect some external power source, e.g. a jump box (some of which supposedly have 20 hours of juice in them), as if to jump the car, then shut the car hood with the battery pack inside (or wire terminals internally, into the cabin somehow) could that prevent car from needing to turn on battery? Alternatively, could this be done with the 12V trunk battery, if a direct connection would be better? For multi-night camping, the jump box could be recharged via the 12v cigarette lighter.

    Anyone try this? If not, any reason why it theoretically wouldn't work?
     
  2. bisco

    bisco cookie crumbler

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    i'm not sure where you are going with this. if you have a battery that will supply 20 hours of power, why do you need to connect it to the car? can't you just connect to the devices you want to power?

    what devices do you want to power? 20 hours is a big battery, considering how big the prius battery is, and how often the engine has to come on to recharge it.
    granted, it only uses and recharges a percentage near the bottom, once the initial charge is gone.
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I get what you're trying to do, but it won't work the way you describe.

    The concept is good, but there's a scale problem. The average jump box contains enough energy to run the average Prius air conditioner for about 6 minutes before it is discharged- and that's after you work out a way to get from the low voltage found in a jump box up to the high voltage used by the HVAC system.

    So, it's a great idea but you're going to need a bigger boa- er, jump box. Much bigger.
     
  4. ChapmanF

    ChapmanF Senior Member

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    The A/C compressor is a large draw; it is supplied by the high voltage system, and can require up to two or three horsepower in operation. How long any jump box would hold up under that kind of load (assuming you were able to find a two hundred volt jump box) would not be anywhere near 20 hours.
     
  5. pc85

    pc85 New Member

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    I guess I underestimated the 'camping generator' that is the Prius gas engine. For what it's worth, memory foam has solved most/all of the [pretty mild] vibration issue for me; just thought this could be a further improvement. Thanks for the insights.

    What about a battery maintainer/charger plugged into outlet via extension cord? The applicability is pretty narrow, but there are some scenarios I can think of (driveway camping, some campground scenarios, etc.). Still have voltage mismatch, or couldn't even keep up with draw? I guess just trying it out is probably the best bet.
     
  6. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Now that you're most of the way to having a window A/C unit propped in the car window is when I'll point out that having an actual window A/C unit propped in the car window is cheaper than whatever you're thinking.
     
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  7. 09Prius2

    09Prius2 Member

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    You would need a grid charger plugged in while the car is running.

    It takes nothing for the hv battery to charge the 12v. The step up amperage to go the other direction would be tremendous. Think melting wires and fires while you're sleeping.

    I tried to run a household inverter off the prius. It melted the jumper cables in about 2 minutes and discharged the 12v battery faster than the system can replenish.

    Either you have to run the ice generator or find a normal place to sleep.
     
  8. pc85

    pc85 New Member

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    Quickly running extension cord and carrying around an A/C window unit not quite same thing. Thanks for the answers though; seems like a no-go.
     
    #8 pc85, Apr 16, 2019
    Last edited: Apr 16, 2019
  9. bisco

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    is stealth camping something like parking in someones driveway in the middle of the night?
     
  10. padroo

    padroo Senior Member

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    The Prius engine starts to either recharge the HV battery or to keep the engine warm. The Prius engine will run to maintain it's temperature to keep it from polluting the air. Cold engines are a major cause of pollution.
     
  11. oil_burner

    oil_burner Active Member

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    Doesn't work. I've tried it with a battery charger hooked to the 12v battery when camping on an RV lot. Keeping the 12v charged will not charge the traction battery and the car will still turn on to run the AC. Better way is to use dark window mesh if it's not too hot.
     
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