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Direct photovoltaic connenction for a notebook

Discussion in 'Laptops' started by Roland Mösl, Aug 6, 2010.

  1. Roland Mösl

    Roland Mösl Guest

    Has any laptop a programable power input?

    The power input is driven by demand.

    This means the DC-DC converter takes
    from the power input as much power as
    the notebook needs.

    This is not suitable for the direct usage
    of photovoltaic.


    When the photovoltaic can only deliver
    15W, but the notebook takes 18W,
    it will not happen, that the notebook
    takes 15W from the input and 3W from
    the battery.

    The DC DC will pull down the PV to
    short cut Ampere.

    So it's necessary to use a buffer battery

    In above case, the PV delivers 15W,
    the laptop needs 18W, the buffer battery
    will deliver 3W and the PV 15W.

    But this requires a car adapter and makes it all very

    1,8 kg leight weigth notebook
    0,8 kg foldable photovoltaic
    2,5 kg lead acid buffer battery
    0,5 kg car adapter

    So it would be very nice to eliminate
    buffer battery and car adapter and to
    use the notebooks internal battery
    as the buffer.

    This requires an intelligent power input circuit.

    There are 2 approaches:

    1.) Recognice that there is a photovoltaic attached
    Take power at constant 12,5 V
    That's not optimal, but will at most times have
    more than 80% of the maximum, the PV can deliver

    2.) Work with MPP tracking.

    MPPT = Maximum Power Point Tracking

    At a given amount of light and temperature,
    the photovoltaic delivers for each voltage
    a given rate of ampere.

    The MPPT tries to find the best combination
    of V and A to get most W out of it.

    So I repeat here my question:

    Has any laptop a programable power input?

    Roland Mösl
    http://car.pege.org cars and traffic
    http://live.pege.org building and live
    Roland Mösl, Aug 6, 2010
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  2. On Aug 6, 9:10 am, Roland Mösl <> wrote:
    > Has any laptop a programable power input?

    I have a laptop that freezes when I connect external power, but works
    ok with battery only, so I experimented a bit and found this:

    disconnected battery positive (+) connection
    connected multimeter to measure battery power
    connected stabilized power supply unit (SPSU), measuring power output,
    in parallel to battery
    my battery output voltage is around 11.4V
    started setting SPSU at 11.4V
    switched laptop on, let windows 7 run
    ampere readings are the same from both battery and SPSU
    rising SPSU voltage output raduces ampere reading from battery, going
    to 0A when output of SPSU is near 13.5V, at the same time the power
    output from SPSU goes up proportionally

    after these tests I am succesfully using the laptop connected to a
    regular PC ATX power supply, using a 12V line, keeping the battery (+)
    disconnected, and all other battery connections connected, so that
    windows is showing the real battery level, 100% going down a bit for

    hope this helps
    Mike De Petris, Aug 9, 2010
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