converting car alt. to 120v ac

Discussion in 'Electronic Design' started by harvy, Jan 28, 2006.

  1. harvy

    harvy Guest

    has anyone ever converted a car altenator to ac 120 power.
    I was kind of looking on the net for how to do this or not.
    I am putting together a log splitter and I was kind of hoping to make
    it an ac generator on top of it when it isnt driving the hydrolics.
     
    harvy, Jan 28, 2006
    #1
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  2. harvy

    Guest

    You would need to rewind the stator, chuck out the diodes and the
    voltage regulator, make your own voltage regulator. Then you need to
    drive it at the right speed and finally you have to deal with the
    3phase output.
     
    , Jan 28, 2006
    #2
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  3. harvy

    kell Guest

    harvy wrote:
    > has anyone ever converted a car altenator to ac 120 power.
    > I was kind of looking on the net for how to do this or not.
    > I am putting together a log splitter and I was kind of hoping to make
    > it an ac generator on top of it when it isnt driving the hydrolics.

    Obviously you're gonna have to open up the alternator. Do you know
    anything about alternators? Tap two of the stator windings' three
    outputs to get your single phase ac. And you have to take the diode
    pack's dc output (this is the alternator's output, normally) and
    connect it directly to the field (bypassing the voltage regulator).
    If you don't need tight regulation of your ac power and the splitter's
    engine has some abilitly to respond to load changes by adjusting its
    torque, you might not need any electronics.
     
    kell, Jan 28, 2006
    #3
  4. harvy

    Pooh Bear Guest

    wrote:

    > You would need to rewind the stator, chuck out the diodes and the
    > voltage regulator, make your own voltage regulator. Then you need to
    > drive it at the right speed and finally you have to deal with the
    > 3phase output.


    Not to mention the frequency.

    Graham
     
    Pooh Bear, Jan 28, 2006
    #4
  5. harvy

    Guest

    harvy wrote:
    > has anyone ever converted a car altenator to ac 120 power.
    > I was kind of looking on the net for how to do this or not.
    > I am putting together a log splitter and I was kind of hoping to make
    > it an ac generator on top of it when it isnt driving the hydrolics.


    just bypass the regulator, which controls the feed to the field. And I
    guess dont use the rectifier, if you want ac. DC will run many ac loads
    though.

    This will of course give you an unregulated generator, which wont give
    any voltage regulation. And the frequency will be high, too high for
    some loads, but fine for many.


    NT
     
    , Jan 28, 2006
    #5
  6. harvy

    Leon Guest

    wrote:
    > You would need to rewind the stator, chuck out the diodes and the
    > voltage regulator, make your own voltage regulator. Then you need to
    > drive it at the right speed and finally you have to deal with the
    > 3phase output.


    How about removing the diodes and adding a suitable transformer?

    Leon
     
    Leon, Jan 28, 2006
    #6
  7. harvy

    Sjouke Burry Guest

    harvy wrote:
    > has anyone ever converted a car altenator to ac 120 power.
    > I was kind of looking on the net for how to do this or not.
    > I am putting together a log splitter and I was kind of hoping to make
    > it an ac generator on top of it when it isnt driving the hydrolics.


    Yes,by accident. My regulator circuit regulated
    the wrong way and when we touched the accelerator,
    the whole board went bang!!!!!!
    The IC missed its hat,and any trace of chip and
    wire kind of disappeared.
    My college was splattered all over with pieces
    of electrolytic capacitor.
     
    Sjouke Burry, Jan 29, 2006
    #7
  8. harvy

    Mark Guest

    Something has always bothered me about this, maye some can explain
    it....

    I know a car alternator can put out about 100 Amps at 12Volts as it is
    designed to by regulating the field winding which is on the rotor.
    This is about 1200 Watts... Ok no problem for an alternator that
    size...

    I also know you can "full field" an alternator and it will put out a
    higher voltage...

    OK, so lets say we full field an alternator and it puts out say 50
    Volts. The stator wires can still handle 100 Amps output , but since
    its at 50 Volts...this is now 5000 Watts. I realize it will take a lot
    more torque to turn the shaft but suppose we have the torque... that
    still seems like a lot of power to get out such a small alternator...


    Is the size required of an alternator detemrined by the current it can
    supply, not the power... can we get more and more power out of an
    alternator of a given size by raising the output voltage (given the
    insulation holds) ?

    What am I missing?


    Mark
     
    Mark, Jan 30, 2006
    #8
  9. harvy wrote:
    >
    > has anyone ever converted a car altenator to ac 120 power.
    > I was kind of looking on the net for how to do this or not.
    > I am putting together a log splitter and I was kind of hoping to make
    > it an ac generator on top of it when it isnt driving the hydrolics.


    Wrong voltage, wrong frequency, wrong number of phases. Your best bet
    (if its 120V, 60 Hz you're after) is to use it to power an inverter.

    --
    Paul Hovnanian mailto:p
    ------------------------------------------------------------------
    When I was in high school, I remember boys and girls slept
    together all the time. We called it algebra class. -- Jay Leno
     
    Paul Hovnanian P.E., Jan 30, 2006
    #9
  10. Mark wrote:
    >
    > Something has always bothered me about this, maye some can explain
    > it....
    >
    > I know a car alternator can put out about 100 Amps at 12Volts as it is
    > designed to by regulating the field winding which is on the rotor.
    > This is about 1200 Watts... Ok no problem for an alternator that
    > size...
    >
    > I also know you can "full field" an alternator and it will put out a
    > higher voltage...
    >
    > OK, so lets say we full field an alternator and it puts out say 50
    > Volts. The stator wires can still handle 100 Amps output , but since
    > its at 50 Volts...this is now 5000 Watts. I realize it will take a lot
    > more torque to turn the shaft but suppose we have the torque... that
    > still seems like a lot of power to get out such a small alternator...
    >
    > Is the size required of an alternator detemrined by the current it can
    > supply, not the power... can we get more and more power out of an
    > alternator of a given size by raising the output voltage (given the
    > insulation holds) ?
    >
    > What am I missing?


    The effects of the series reactance of the alternator windings. The
    device might be able to put out 50V at no load, but, for a given value
    of field current (and RPM) the terminal voltage will drop off as load
    increases. At full field, the alternator will put out significantly less
    than he no-load voltage times the full load amps.

    --
    Paul Hovnanian mailto:p
    ------------------------------------------------------------------
    Drugs may be the road to nowhere, but at least they're the scenic route!
     
    Paul Hovnanian P.E., Jan 30, 2006
    #10
  11. An automotive alternator is a three-phase configuration, so each winding
    only handles roughly 1/3 the DC output current. So if you could rewind a 100
    amp it for single phase output you might get 12 x 3 x 1.414 = 50 VAC at 33
    amps, or about 1500 watts. However, the alternator is designed to provide at
    least 12 VDC at idle speed, say 600 RPM, and will probably put out 6 times
    that at 3600 RPM,or 300 VAC. The magnetics will probably limit it to
    something lower than that, but it might be possible to get 120 VAC at 30
    amps = 3600 watts. However, it's probably something like 400 Hz, so you
    couldn't use it for motor loads, unless you want them to spin *really* fast!

    I haven't thought this out completely, but it's worth discussing.

    Paul E. Schoen
     
    Paul E. Schoen, Jan 30, 2006
    #11
  12. harvy

    kell Guest

    Mark wrote:
    > Something has always bothered me about this, maye some can explain
    > it....
    >
    > I know a car alternator can put out about 100 Amps at 12Volts as it is
    > designed to by regulating the field winding which is on the rotor.
    > This is about 1200 Watts... Ok no problem for an alternator that
    > size...
    >
    > I also know you can "full field" an alternator and it will put out a
    > higher voltage...
    >
    > OK, so lets say we full field an alternator and it puts out say 50
    > Volts. The stator wires can still handle 100 Amps output , but since
    > its at 50 Volts...this is now 5000 Watts. I realize it will take a lot
    > more torque to turn the shaft but suppose we have the torque... that
    > still seems like a lot of power to get out such a small alternator...
    >
    >
    > Is the size required of an alternator detemrined by the current it can
    > supply, not the power... can we get more and more power out of an
    > alternator of a given size by raising the output voltage (given the
    > insulation holds) ?
    >
    > What am I missing?
    >
    >
    > Mark


    Think about the fact that the regulator probably makes the alternator
    go full field pretty much anyway, when the output has a very heavy load
    on it -- your hypothetical 100 amps. It's already full field at 100
    amps and you're only getting 15 volts -- not 50.
     
    kell, Jan 30, 2006
    #12
  13. harvy

    Jim Thompson Guest

    On 30 Jan 2006 07:55:53 -0800, "kell" <>
    wrote:

    >
    >Mark wrote:


    [snip]

    >>
    >> What am I missing?
    >>
    >>
    >> Mark

    >
    >Think about the fact that the regulator probably makes the alternator
    >go full field pretty much anyway, when the output has a very heavy load
    >on it -- your hypothetical 100 amps. It's already full field at 100
    >amps and you're only getting 15 volts -- not 50.


    You are forgetting that an automotive alternator is essentially a
    current source.

    As built, if you remove the diodes, they produce 3-phase AC. The
    voltage will be a function of the load and the field current.

    ...Jim Thompson
    --
    | James E.Thompson, P.E. | mens |
    | Analog Innovations, Inc. | et |
    | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
    | Phoenix, Arizona Voice:(480)460-2350 | |
    | E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
    | http://www.analog-innovations.com | 1962 |

    "Don't mess with my toot toot!", Antoine 'Fats' Domino
     
    Jim Thompson, Jan 30, 2006
    #13
  14. harvy

    kell Guest

    Jim Thompson wrote:
    > On 30 Jan 2006 07:55:53 -0800, "kell" <>
    > wrote:
    >
    > >
    > >Mark wrote:

    >
    > [snip]
    >
    > >>
    > >> What am I missing?
    > >>
    > >>
    > >> Mark

    > >
    > >Think about the fact that the regulator probably makes the alternator
    > >go full field pretty much anyway, when the output has a very heavy load
    > >on it -- your hypothetical 100 amps. It's already full field at 100
    > >amps and you're only getting 15 volts -- not 50.

    >
    > You are forgetting that an automotive alternator is essentially a
    > current source.
    >
    > As built, if you remove the diodes, they produce 3-phase AC. The
    > voltage will be a function of the load and the field current.
    >
    > ...Jim Thompson


    I think we can agree Mark won't get an alternator to put out five times
    as much power just from bypassing the voltage regulator.
     
    kell, Jan 30, 2006
    #14
  15. harvy

    Jim Thompson Guest

    On 30 Jan 2006 13:56:48 -0800, "kell" <>
    wrote:

    >
    >Jim Thompson wrote:
    >> On 30 Jan 2006 07:55:53 -0800, "kell" <>
    >> wrote:
    >>
    >> >
    >> >Mark wrote:

    >>
    >> [snip]
    >>
    >> >>
    >> >> What am I missing?
    >> >>
    >> >>
    >> >> Mark
    >> >
    >> >Think about the fact that the regulator probably makes the alternator
    >> >go full field pretty much anyway, when the output has a very heavy load
    >> >on it -- your hypothetical 100 amps. It's already full field at 100
    >> >amps and you're only getting 15 volts -- not 50.

    >>
    >> You are forgetting that an automotive alternator is essentially a
    >> current source.
    >>
    >> As built, if you remove the diodes, they produce 3-phase AC. The
    >> voltage will be a function of the load and the field current.
    >>
    >> ...Jim Thompson

    >
    >I think we can agree Mark won't get an alternator to put out five times
    >as much power just from bypassing the voltage regulator.


    The alternator WILL put out the power... until it starts to melt ;-)

    ...Jim Thompson
    --
    | James E.Thompson, P.E. | mens |
    | Analog Innovations, Inc. | et |
    | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
    | Phoenix, Arizona Voice:(480)460-2350 | |
    | E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
    | http://www.analog-innovations.com | 1962 |

    "Don't mess with my toot toot!", Antoine 'Fats' Domino
     
    Jim Thompson, Jan 30, 2006
    #15
  16. harvy

    Mark Guest

    Jim Thompson wrote:
    > On 30 Jan 2006 13:56:48 -0800, "kell" <>
    > wrote:
    >
    > >
    > >Jim Thompson wrote:
    > >> On 30 Jan 2006 07:55:53 -0800, "kell" <>
    > >> wrote:
    > >>
    > >> >
    > >> >Mark wrote:
    > >>
    > >> [snip]
    > >>
    > >> >>
    > >> >> What am I missing?
    > >> >>
    > >> >>
    > >> >> Mark
    > >> >
    > >> >Think about the fact that the regulator probably makes the alternator
    > >> >go full field pretty much anyway, when the output has a very heavy load
    > >> >on it -- your hypothetical 100 amps. It's already full field at 100
    > >> >amps and you're only getting 15 volts -- not 50.
    > >>
    > >> You are forgetting that an automotive alternator is essentially a
    > >> current source.
    > >>
    > >> As built, if you remove the diodes, they produce 3-phase AC. The
    > >> voltage will be a function of the load and the field current.
    > >>
    > >> ...Jim Thompson

    > >
    > >I think we can agree Mark won't get an alternator to put out five times
    > >as much power just from bypassing the voltage regulator.

    >
    > The alternator WILL put out the power... until it starts to melt ;-)
    >
    > ...Jim Thompson


    That is the point of my question...why would it melt...?

    The stator is designed to deliver 100 Amps. When you full field it and
    the voltage is say 50 Volts, if the current is still 100 Amps the I^2R
    losses are still the same so it wouldn't get any hotter compared to
    when it delivers 100 Amps at 12 Volts.

    Mark
     
    Mark, Jan 31, 2006
    #16
  17. harvy

    Jim Thompson Guest

    On 30 Jan 2006 19:59:44 -0800, "Mark" <> wrote:

    >
    >Jim Thompson wrote:
    >> On 30 Jan 2006 13:56:48 -0800, "kell" <>
    >> wrote:
    >>
    >> >
    >> >Jim Thompson wrote:
    >> >> On 30 Jan 2006 07:55:53 -0800, "kell" <>
    >> >> wrote:
    >> >>
    >> >> >
    >> >> >Mark wrote:
    >> >>
    >> >> [snip]
    >> >>
    >> >> >>
    >> >> >> What am I missing?
    >> >> >>
    >> >> >>
    >> >> >> Mark
    >> >> >
    >> >> >Think about the fact that the regulator probably makes the alternator
    >> >> >go full field pretty much anyway, when the output has a very heavy load
    >> >> >on it -- your hypothetical 100 amps. It's already full field at 100
    >> >> >amps and you're only getting 15 volts -- not 50.
    >> >>
    >> >> You are forgetting that an automotive alternator is essentially a
    >> >> current source.
    >> >>
    >> >> As built, if you remove the diodes, they produce 3-phase AC. The
    >> >> voltage will be a function of the load and the field current.
    >> >>
    >> >> ...Jim Thompson
    >> >
    >> >I think we can agree Mark won't get an alternator to put out five times
    >> >as much power just from bypassing the voltage regulator.

    >>
    >> The alternator WILL put out the power... until it starts to melt ;-)
    >>
    >> ...Jim Thompson

    >
    >That is the point of my question...why would it melt...?
    >
    >The stator is designed to deliver 100 Amps. When you full field it and
    >the voltage is say 50 Volts, if the current is still 100 Amps the I^2R
    >losses are still the same so it wouldn't get any hotter compared to
    >when it delivers 100 Amps at 12 Volts.
    >
    >Mark


    Good point.

    ...Jim Thompson
    --
    | James E.Thompson, P.E. | mens |
    | Analog Innovations, Inc. | et |
    | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
    | Phoenix, Arizona Voice:(480)460-2350 | |
    | E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
    | http://www.analog-innovations.com | 1962 |

    Global Warming is God's gift to the Blue States ;-)
     
    Jim Thompson, Jan 31, 2006
    #17
  18. harvy

    Pooh Bear Guest

    Mark wrote:

    > Jim Thompson wrote:
    > > On 30 Jan 2006 13:56:48 -0800, "kell" <>
    > > wrote:
    > >
    > > >
    > > >Jim Thompson wrote:
    > > >> On 30 Jan 2006 07:55:53 -0800, "kell" <>
    > > >> wrote:
    > > >>
    > > >> >
    > > >> >Mark wrote:
    > > >>
    > > >> [snip]
    > > >>
    > > >> >>
    > > >> >> What am I missing?
    > > >> >>
    > > >> >>
    > > >> >> Mark
    > > >> >
    > > >> >Think about the fact that the regulator probably makes the alternator
    > > >> >go full field pretty much anyway, when the output has a very heavy load
    > > >> >on it -- your hypothetical 100 amps. It's already full field at 100
    > > >> >amps and you're only getting 15 volts -- not 50.
    > > >>
    > > >> You are forgetting that an automotive alternator is essentially a
    > > >> current source.
    > > >>
    > > >> As built, if you remove the diodes, they produce 3-phase AC. The
    > > >> voltage will be a function of the load and the field current.
    > > >>
    > > >> ...Jim Thompson
    > > >
    > > >I think we can agree Mark won't get an alternator to put out five times
    > > >as much power just from bypassing the voltage regulator.

    > >
    > > The alternator WILL put out the power... until it starts to melt ;-)
    > >
    > > ...Jim Thompson

    >
    > That is the point of my question...why would it melt...?
    >
    > The stator is designed to deliver 100 Amps. When you full field it and
    > the voltage is say 50 Volts, if the current is still 100 Amps the I^2R
    > losses are still the same so it wouldn't get any hotter compared to
    > when it delivers 100 Amps at 12 Volts.


    I think you'll find the on-load voltage drops though on account of the alternator
    impedance.

    Graham
     
    Pooh Bear, Jan 31, 2006
    #18
  19. harvy

    Guest

    Leon wrote:
    > wrote:
    > > You would need to rewind the stator, chuck out the diodes and the
    > > voltage regulator, make your own voltage regulator. Then you need to
    > > drive it at the right speed and finally you have to deal with the
    > > 3phase output.

    >
    > How about removing the diodes and adding a suitable transformer?
    >
    > Leon


    Yep that would work but he still needs speed regulation and a 3 phase
    transformer.
     
    , Jan 31, 2006
    #19
  20. harvy

    Pooh Bear Guest

    wrote:

    > Leon wrote:
    > > wrote:
    > > > You would need to rewind the stator, chuck out the diodes and the
    > > > voltage regulator, make your own voltage regulator. Then you need to
    > > > drive it at the right speed and finally you have to deal with the
    > > > 3phase output.

    > >
    > > How about removing the diodes and adding a suitable transformer?
    > >
    > > Leon

    >
    > Yep that would work but he still needs speed regulation and a 3 phase
    > transformer.


    A 3-phase transfomer still needs a 3-phase load !

    Graham
     
    Pooh Bear, Jan 31, 2006
    #20
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