Converting 12V DC Current (From a vehicle) to 120V A/C

Discussion in 'Alternative Energy' started by Rick, Mar 28, 2006.

  1. Rick

    Rick Well-Known Member Supporter

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    I have a couple of questions....

    Background: I have a block heater on my Diesel Pick-up that measured 590 Watt power usage on a Kill A Watt. It didn't seem to surge at all, but let's figure a 1000 watt inverter is needed.

    My first question is, would I loose many watts by using a 2500 watt inverter for such a lower need?

    My second question is, could I expect the charging system in a 1.5 Honda Civic engine to generate the power that a 600W, 1000W or 2500W inverter would need?

    Thanks,

    Rick
     
  2. wy_white_wolf

    wy_white_wolf Just howling at the moon

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    It really matters on the manufacture of the inverters but most I've looked at wouldn't be but 10 to 20 watts apart

    I would say no to all of them. 600w would be (600/12) 50 amps at 12volt. I don't think that little alt. is that big and it would also have to supply amps for the vehicle to run. I think propably about a 75 amp alt would be min to draw the 600w from.

    Thinking outside the box -

    How about rigging up some quick disconnect heater hoses to use engine coolant from the civic to warm up the truck? We had setup like that to warm-up a D-8 cat from our pickup. It would only take about 15 min to move the temp gauge on the cat when it was -20 F out.
     

  3. Rick

    Rick Well-Known Member Supporter

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    I like that kind of thinking. I would need to freshen up the antifreeze in the poor, old car.


    Thanks,

    Rick
     
  4. JAK

    JAK Well-Known Member

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    As far as I know a block heater is a simple resistance device, so you could feed it a lower voltage, even 12v DC. You will get less heat, but you will also draw a lot less amps off you battery.

    590 watts / 115 volts = 5.13 amps
    115 volts / 5.13 amps = 22.4 ohms

    Running on one 12volt battery for 8 hours:
    12.0 volts / 22.4 ohms ~ 0.5 amps
    8 hours x 0.5 amps = 4.0 amp-hours
    12.0 volts x 0.5 amps = 6.0 watts
    6.0 watts x 3.413 = 20.5 BTU/hour

    Running on two 12volt battery in series for 8 hours:
    24.0 volts / 22.4 ohms ~ 1.0 amps
    8 hours x 1.0 amps = 8.0 amp-hours from each battery
    24.0 volts x 1.0 amps = 24.0 watts
    24.0 watts x 3.413 = 82 BTU/hour

    It might only warm up the oil a few degrees, but it at least it won't run the batteries down. The batteries also run alot more efficiently at a low current draw and you eliminate the cost and inefficiency of the inverter. I would guess steady state would be reached in one hour so it might be better to put it on a timer. Of course there are other options for heating than using the battery. That radiator coolant idea sounded good. A pan of boiling water or a small candle under the engine might be safe enough in a jam. Or you could just start the darn thing cold. 5W-30 helps.
     
  5. John Hill

    John Hill Grand Master

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    Hmmmm! I wonder how effective it would be to blow Honda Civic hot exhaust gases through the front of the truck's radiator?
     
  6. barn-apart

    barn-apart Well-Known Member

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    Rick,
    I believe most power inverters run off the battery, so if your car has a full charged battery any size inverter should function for your purpose . A larger watt will generaly draw more idle amps.I use mine for other purposes , refrigerator, battery chargers for cordless tools, 110v lights, ect. Often using it without the vehicle running. Handiest things those inverters.
    Rick
     
  7. RobD

    RobD Active Member

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    Rick,
    I don't know if this would help but I live in a cold climate too so I'll suggest what I do. I don't use block heaters I use sythetic oil and teflon filters. Between the two I can turn my car over at 20 below (F) with no problems. I did this for someone who worked all day and had no way to heat her block after eight or nine hours. Guess what? More often then not she drove away when a lot of other people didn't!

    I use the teflon filter from Fram with sythetic oil from Castrol. You can use Slick 50 but try to get the emulsion suspended in sythetic oil not regular oil.

    The plus is your mileage will go up too!

    RobD
     
  8. Rick

    Rick Well-Known Member Supporter

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    Thanks Rob. Is that diesel or gas fuel- just curious.
    I shouldn't drop below 0 degrees F, so that should more than account for the diesel engine.

     
  9. RobD

    RobD Active Member

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    The cars I run are on gas but I don't see a problem with diesel. In fact I would think diesels would 'like' sythetics.

    One more thing once you have run enough teflon into your engine you don't need to use a teflon filter any longer and you can just run synthetic. That should happen after the first teflon filter or Slick 50 oil change. If you run the slick 50 with regular oil in it then do it in the summer and run regular oil in your vehicle. When it comes to an oil change then you can go with the synthetic oil and a standard filter.

    I alternate teflon and extended life filters. Once I run synthetic in my car I only change the oil once a year. I change the filter at the end of its advised mileage by the manufacturer. I've had a couple of 250k mileage engines with no problems (gas). Diesel should last longer but you might have to change the oil even though it's synthetic. Talk to someone who really knows diesels on this. It's not my area of expertise.

    Rob

    ps. 0-F is no problem. I've seen 20 below for a couple of weeks.
     
  10. Rick

    Rick Well-Known Member Supporter

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    My gut tells me that WWW is right, but my heart cries out for an cheap, easy solution.

    barn-apart....how many amps is that refrig?? It must be more than 6 amps!
     
  11. Rick

    Rick Well-Known Member Supporter

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    Sorry about that- you must have wonderful Summers!

    We just experienced our first 18 degree F night- with a propane heater in the motor home (28 degrees inside) to warm things up in the morning!

    Rick
     
  12. barn-apart

    barn-apart Well-Known Member

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    Fridge is 3 cu. ft. draws 3.5 amps We run it during the summer for cold drinks and to keep lunch in.As well as charging the 18v cordless batteries (couple a day) during work without the truck running, and still start the truck after work. I use a 750 watt contiuous. The battery is a standard 12v that was in the truck when I bought it a year or so ago.
    Rick
     
  13. wy_white_wolf

    wy_white_wolf Just howling at the moon

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    A frig. is a lot different type of load. It only has to run for 5 or 10 min. every hour to stay cold, were as a block heater pulls a continous load. Same with charging the batteries. Load turns off once the batteries are charged.

    Rick
    The easy solution here would be to use like a 1000w generater to run the block heater. Propably cheaper on gas to than the honda.
     
  14. RobD

    RobD Active Member

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    Trade offs.
    No ticks, chiggers,copperheads or neighbors. No windmill or solar panel restrictions, a 12 foot deep stocked trout pond and a stream.
     
  15. Rick

    Rick Well-Known Member Supporter

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    Yeah- I know; It's right around the bend. I have resisted getting one- we'll start to use it and rely on it :(