NEED VOLTAGE REGULATOR 14V 40 AMPS

Discussion in 'Electronic Design' started by Ducky_Doug, Dec 20, 2004.

  1. Ducky_Doug

    Ducky_Doug Guest

    After starting my Chevy Duramax Deisel the alternator puts out over 15.5V
    and then drops down after a few minutes. This caused my 400W Portawatt
    inverter to drop out on high voltage. Is there a simple circuit using
    mosfets, 2n3055, etc and using readily available parts to drop the voltage
    down to <15V. Regulation isn't neccessary just want to keep the voltage
    between the inverters shutdown setpoints.
     
    Ducky_Doug, Dec 20, 2004
    #1
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  2. Ducky_Doug

    CBarn24050 Guest

    Your alternator should not put out that much, you need a new voltage regulator
    or maybe a new battery.
     
    CBarn24050, Dec 20, 2004
    #2
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  3. Ducky_Doug

    Fred Bloggs Guest


    > After starting my Chevy Duramax Deisel the alternator puts out over 15.5V
    > and then drops down after a few minutes. This caused my 400W Portawatt
    > inverter to drop out on high voltage. Is there a simple circuit using
    > mosfets, 2n3055, etc and using readily available parts to drop the voltage
    > down to <15V. Regulation isn't neccessary just want to keep the voltage
    > between the inverters shutdown setpoints.
    >


    View in a fixed-width font such as Courier.



    50A L
    p-ch ====
    Vbatt o--+---------+ +------------+--uuuu---+--->
    | v | | |
    | ---- - |
    | | ^sd |
    +--[r]-----+--------+ - |
    | | | +---+
    [r] | | | |
    | | | | |
    | | | | |
    +-------+------+ | | | ===
    | | | | | | |
    - [r] | | | [r] |
    ^ zd | | | | | |
    - +----|\| | | +---|-+
    | | |-\ | | | | |
    | [r] | >---+ | [r] | |
    | | +-|+/ comptor | | | |
    | | | |/| | | | |
    | | | | | | | |
    +---+-------+--|---+----------+-----+---+ |
    | | |
    --- +--------------------------+
    ///
     
    Fred Bloggs, Dec 20, 2004
    #3
  4. Ducky_Doug

    Tam/WB2TT Guest

    "Ducky_Doug" <> wrote in message
    news:...
    > After starting my Chevy Duramax Deisel the alternator puts out over 15.5V
    > and then drops down after a few minutes. This caused my 400W Portawatt
    > inverter to drop out on high voltage. Is there a simple circuit using
    > mosfets, 2n3055, etc and using readily available parts to drop the voltage
    > down to <15V. Regulation isn't neccessary just want to keep the voltage
    > between the inverters shutdown setpoints.
    >

    Where is the inverter connected? If near the alternator, connect it to the
    battery terminals; BOTH negative and positive leads. In my car, the battery
    is under the rear seat. I often see over 15 volts under the hood/ at the
    cigarette lighter. No damage to the battery in over 4 years.

    Tam
     
    Tam/WB2TT, Dec 20, 2004
    #4
  5. Ducky_Doug

    Ducky_Doug Guest

    Thank you for your responses. A #1 welding cable runs from the engine
    batteries and feeds the 400 watt inverter in the cab. The buss then
    continues on to feed a 2500 watt inverter and 400 amphr deep cycle type
    aux. batteries in the back of the service truck. This setup is duplicated
    in two of our other sevice trucks and they also suffer from shut down of
    the cab inverter which runs a computer and test equipment. The 2.5K
    inverter is not a concern. This only happens on our deisel equiped trucks
    and GM assures us that this higher first recharge voltage is normal to a
    deisel due to its high output alternator. A resistive device is out as it
    only acts as a current limiter.
     
    Ducky_Doug, Dec 23, 2004
    #5
  6. Fred Bloggs wrote...
    >
    > "Ducky Doug" Braun wrote ...
    >>
    >> After starting my Chevy Duramax Deisel the alternator puts out over
    >> 15.5V and then drops down after a few minutes. This caused my 400W
    >> Portawatt inverter to drop out on high voltage. Is there a simple
    >> circuit using mosfets, 2n3055, etc and using readily available parts
    >> to drop the voltage down to <15V. Regulation isn't neccessary just
    >> want to keep the voltage between the inverters shutdown setpoints.


    CBarn24050 and Tam/WB2TT pointed out that if the Portawatt inverter
    were wired directly across the 12V battery terminals, then voltages
    over 15V shouldn't occur. Can Ducky Doug comment on this?

    > 50A L
    > p-ch ====
    > Vbatt o--+---------+ +------------+--uuuu---+--->
    > | v | | |
    > | ---- - |
    > | | ^sd |
    > +--[r]-----+--------+ - |
    > | | | +---+
    > [r] | | | |
    > | | | | |
    > +-------+------+ | | | ===
    > | | | | | | |
    > - [r] | | | [r] |
    > ^ zd | | | | | |
    > - +----|\| | | +---|-+
    > | | |-\ | | | | |
    > | [r] | >---+ | [r] | |
    > | | +-|+/ comptor | | | |
    > | | | |/| | | | |
    > +---+-------+--|---+----------+-----+---+ |
    > | | |
    > --- +--------------------------+
    > ///


    Hmm, a bit easier said than done. What's a good choice for the
    p-channel MOSFET, which should have Ron below 5 milliohms? This
    FET will have a rather high gate capacitance, mandating a proper
    gate driver. At which point the designer will begin considering
    the attractive n-channel MOSFET plus driver solutions.

    And the low-resistance 50A inductor will be fun as well. Using
    a low-inductance part will help the designer to meet the low-
    resistance requirement, but this will mandate higher switching
    frequencies, which in turn mandates a serious FET gate driver.


    --
    Thanks,
    - Win
     
    Winfield Hill, Dec 23, 2004
    #6
  7. Ducky_Doug

    Fred Bloggs Guest

    Winfield Hill wrote:
    > Fred Bloggs wrote...
    >
    >>"Ducky Doug" Braun wrote ...
    >>
    >>>After starting my Chevy Duramax Deisel the alternator puts out over
    >>>15.5V and then drops down after a few minutes. This caused my 400W
    >>>Portawatt inverter to drop out on high voltage. Is there a simple
    >>>circuit using mosfets, 2n3055, etc and using readily available parts
    >>>to drop the voltage down to <15V. Regulation isn't neccessary just
    >>>want to keep the voltage between the inverters shutdown setpoints.

    >>

    >
    > CBarn24050 and Tam/WB2TT pointed out that if the Portawatt inverter
    > were wired directly across the 12V battery terminals, then voltages
    > over 15V shouldn't occur. Can Ducky Doug comment on this?
    >
    >
    >> 50A L
    >> p-ch ====
    >> Vbatt o--+---------+ +------------+--uuuu---+--->
    >> | v | | |
    >> | ---- - |
    >> | | ^sd |
    >> +--[r]-----+--------+ - |
    >> | | | +---+
    >> [r] | | | |
    >> | | | | |
    >> +-------+------+ | | | ===
    >> | | | | | | |
    >> - [r] | | | [r] |
    >> ^ zd | | | | | |
    >> - +----|\| | | +---|-+
    >> | | |-\ | | | | |
    >> | [r] | >---+ | [r] | |
    >> | | +-|+/ comptor | | | |
    >> | | | |/| | | | |
    >> +---+-------+--|---+----------+-----+---+ |
    >> | | |
    >> --- +--------------------------+
    >> ///

    >
    >
    > Hmm, a bit easier said than done. What's a good choice for the
    > p-channel MOSFET, which should have Ron below 5 milliohms? This
    > FET will have a rather high gate capacitance, mandating a proper
    > gate driver. At which point the designer will begin considering
    > the attractive n-channel MOSFET plus driver solutions.
    >
    > And the low-resistance 50A inductor will be fun as well. Using
    > a low-inductance part will help the designer to meet the low-
    > resistance requirement, but this will mandate higher switching
    > frequencies, which in turn mandates a serious FET gate driver.
    >
    >


    Not to mention blowing out the inverter filter capacitors with excessive
    ripple current....
     
    Fred Bloggs, Dec 23, 2004
    #7
  8. Ducky_Doug

    Kim Clay Guest

    On Mon, 20 Dec 2004 01:07:13 -0500, "Ducky_Doug" <>
    wrote:

    >After starting my Chevy Duramax Deisel the alternator puts out over 15.5V
    >and then drops down after a few minutes. This caused my 400W Portawatt
    >inverter to drop out on high voltage. Is there a simple circuit using
    >mosfets, 2n3055, etc and using readily available parts to drop the voltage
    >down to <15V. Regulation isn't neccessary just want to keep the voltage
    >between the inverters shutdown setpoints.


    How about a single diode in series with the Pos input of the 400W
    inverter (with large heat sink). Diode will drop 0.7V @ 40A= 28W of heat
    to get rid of.

    Maybe 1/2 of a battery isolator or use both diodes of a 2 battery
    isolator & strap both diodes in parallel. You will need good air
    circulation to dump the heat.

    The inverter may drop out quickly due to low volts if used without the
    engine running. The diode will drop a constant 0.7V or so. If the
    inverter was set to dropout at 10.5V it would now drop out at ~11.2V.

    In your case this may not be a problem.

    Just an idea - Kim
     
    Kim Clay, Dec 23, 2004
    #8
  9. Winfield Hill wrote...
    >
    > Fred Bloggs wrote...
    >
    >> 50A L
    >> p-ch ====
    >> Vbatt o--+---------+ +------------+--uuuu---+--->
    >> | v | | |
    >> | ---- - |
    >> | | ^sd |
    >> +--[r]-----+--------+ - |
    >> | | | +---+
    >> [r] | | | |
    >> | | | | |
    >> +-------+------+ | | | ===
    >> | | | | | | |
    >> - [r] | | | [r] |
    >> ^ zd | | | | | |
    >> - +----|\| | | +---|-+
    >> | | |-\ | | | | |
    >> | [r] | >---+ | [r] | |
    >> | | +-|+/ comptor | | | |
    >> | | | |/| | | | |
    >> +---+-------+--|---+----------+-----+---+ |
    >> | | |
    >> --- +--------------------------+
    >> ///

    >
    > Hmm, a bit easier said than done. What's a good choice for
    > the p-channel MOSFET, which should have Ron below 5 milliohms?
    > This FET will have a rather high gate capacitance...


    A few possibilities (through-hole packages only). Note the
    high gate capacitances.

    part Vdss Ron Ciss
    number ohms pF
    ------ ---- ----- ----
    IRF9540 100V 0.2 1400
    IRF9Z30 50V 0.14 900
    IRF9Z34 60V 0.14 1100
    IRF5305 55V 0.06 1200
    FQA47P06 60V 0.026 3600
    NDP6030PL 30V 0.025 1570
    MTP50P03 30V 0.025 4900
    SPP80P06 60V 0.023 5033
    IRF4905 55V 0.020 3400
    2SJ555 60V 0.017 4100
    STP80PF55 55V 0.016 5500
    SUP90P06-09L 60V 0.015 9200
    FX70UMJ 30V 0.012 11140
    SUP75P05-08 55V 0.008 8500




    --
    Thanks,
    - Win
     
    Winfield Hill, Dec 23, 2004
    #9
  10. In article
    <>,
    Ducky_Doug <> wrote:
    > Thank you for your responses. A #1 welding cable runs from the
    > engine batteries and feeds the 400 watt inverter in the cab. The
    > buss then continues on to feed a 2500 watt inverter and 400 amphr
    > deep cycle type aux. batteries in the back of the service truck.
    > This setup is duplicated in two of our other sevice trucks and
    > they also suffer from shut down of the cab inverter which runs a
    > computer and test equipment.


    It might be better to route directly from the engine
    batteries to the aux battery. Then distribute from
    the aux battery to the inverters. In this way the aux
    battery has a better chance of functioning as an
    additional shunt voltage regulator.

    If the problem still persists then maybe a bit of
    brute force and ignorance would solve the problem.

    Have two meaty diodes in series with the supply to
    the 400W device, with automobile-type high current
    contactors holding shorts across the diodes. If the
    upstream voltage exceeds 14.5V then unshort one diode,
    and unshort the other above about 15.5V. Have about
    a 0.5V comparator hysteresis. Maybe cool the diode
    heatsinks with a 12V fan when a diode is unshorted.

    --
    Tony Williams.
     
    Tony Williams, Dec 24, 2004
    #10
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