For those using their Prius as a backup power source, I found an intersting device

Discussion in 'Gen 3 Prius Technical Discussion' started by markf57, Jan 16, 2011.

  1. markf57

    markf57 Junior Member

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    There have been other threads about using the Prius as a backup power source. I seems there are 2 different ways. One is the PriUPS method which is very elaborate and uses the HV battery. The other is just connecting an inverter to the 12v battery and running a few extension cords into you home to power the critical items.

    Since I only want a few items powered, I'm opting for the inverter method. However, one of the key items I wanted to be able to provide power for is the furnace. There really is not way to tap into a furnace - unlike a fridge that you can just plug into an extension. I guess there is backfeeding, but that is very dangerous.

    I recently found this item on eBay that allows a person to tap into any 110v circuit. It seems like it would work well especially on the furnace circuit.

    Generator Transfer Switch - EZ Generator Switch - eBay (item 200565582429 end time Jan-24-11 16:37:13 PST)

    There is more info on the sellers website as well.

    Any comments?
     
    #1 markf57, Jan 16, 2011
  2. pEEf

    pEEf Engineer - EV nut

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    All you'd need to do is install a standard cord and plug on your furnace. Then where the original hardwire was, put a standard box/outlet and plug it back in. In the event of an outage, you can simply unplug the furnace from the "wall" just like anything else and plug it into an extension cord to your backup source.

    Word of warning, many furnace blowers drain significant current, so your inverter would have to be able to handle this. If your inverter draw exceeds the ability of the Prius DC/DC converter, then the 12v battery will get low and the inverter will shut down. This is why many people have went the more complex route of tapping the HV bus. You can probably only pull about 100a from the 12v system in the Prius before you exceed the DC/DC converter's output. In most inverters that's going to be somewhere less than 1000w (assuming typical efficiency).

    A furnace blower motor is usually a single-phase capacitor-run motor, and these have poor power factor, so may well pull more than 1000w from an inverter! Before you depend on your backup system, you should test it!
     
    #2 pEEf, Jan 16, 2011
  3. Troyroy

    Troyroy Member

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    Don't spend $59.00 for that switch......Do as previous post tells you. Material may cost you appox. $10.00 and his method is better for you.

    Just unplug your furnace and plug your furnace into a extension cord from your generator source. This will only supply power to your furnace, nothing else in the home.
     
    #3 Troyroy, Jan 16, 2011
  4. markf57

    markf57 Junior Member

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    Guys:

    Thanks for the input.

    I have one of those newer fancy variable speed ecm furnace motors that draws very little power. At low speed around 250 watts and high around 400 watts.

    As far as adding a plug and an outlet, that does sound easy. But that would require an extension cord run into the house and down the stairs to the the basement. The electrical panel is in the garage much closer to the car and would be cleaner overall, but I might just add the outlet to test the performance of the inverter to make sure it works.
     
    #4 markf57, Jan 16, 2011
  5. cit1991

    cit1991 New Member

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    I did the male/female plug thing. Make sure wherever you wire it, that the 24V power supply is fed, so the thermostat works too.

    Also, be sure to go buy some "heavy duty" 12 gauge extension cords. I'd avoid the 14 or 16 gauge versions for use with an induction motor.
     
    #5 cit1991, Jan 17, 2011
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