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Thread: power problems while car is running..

  1. #21
    Variable Bitrate numbers's Avatar
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    Well I'm not so sure about the age of those cars and how it affects their voltages, but I do know that however old those cars were when this thread was started.... they are about five years older now.

  2. #22
    FLAC
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    EL CAMINO's Avatar
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    well i think this is going way out of the question,is just a simple question,it is true about the voltage is out of range,he mention about 12.68v with the battery only,and with the alternator 17v. next step is to get a second reading from a second voltmeter,if it gets the same numbers well you know the answer,another advice is,i have the bad habit of check and double check my conections dont forget ground shut be very solid the conection also.another thing,is true that old cars have some use,including the alternator,but that's not a problem.you can upgrade some components like a "high performance alternators" some people do and is not going to kill your car.even new cars owners do.i like old cars. and i respect people who like new cars style.

  3. #23
    lez
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    had not noticed the inverter was 140 watt, what a cheap inverter.

    rule of thumb get twice as much as you need.

    buy a 300w FFS. its not bank breaking.

  4. #24
    Variable Bitrate roadhog's Avatar
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    Coo an old thread dusted off. You can almost see the avatars blinking in the new sunlight! Bit like the Queen when I open my wallet....

    So if 17 volts is the norm, why is it called a 12v system? Does Tim now know? Does he even care? Watch this space....

  5. #25
    lez
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    17 is not normal.

  6. #26
    Variable Bitrate roadhog's Avatar
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    I know that, you know that, but Does Tim Know That?

  7. #27
    Admin. Linux loser.
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    Holy old thread alert, Batman! The guy has probably sold this car by now.

    Lez - you started this...
    Quote Originally Posted by ghettocruzer View Post
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    Want to:
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  8. #28
    lez
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    yup I admit it - trainee post whore............

    I never noticed its age but just found in control panel you can ignore old threads, i've turned that on....
    Lez, more widely known as flez1966

  9. #29
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    Hmmm,

    Your first mistake was to buy anything from Radio junk Shack, specially
    a peice of test equipment. Never trust anything from radio junk shack.
    Go get a good fluke meter, or if your a bit on the cheap side, go buy a sears, its a Cheap fluke in disguise.
    14.2 -14.4 vdc is the max that the battery can take and not boil the
    sulfuric acid. Normal low charge is 13.6 progressing to 14.2-14.4 vdc.
    Check your battery without the vehicle running, should be close to 12VDC.
    If its more than a coupe of tenths of a volt low when checking with the
    enginer off, after running the vehicle, then you probably have a cell going bad, and it is very possible to see a higher voltage during charging, as there
    is nothing to load the system down.

    One thing might be being missed here. The alternator is an AC generating
    device, three phase, feeding a set of full wave rectifiers and outputing
    a dc voltage. If one of the rectifiers if open, you may have an unbalanced
    rectification condition causing less that a flat DC voltage, and have some
    AC riding with the DC. The DC to AC inverter is not going to like any
    AC component riding in with the DC. alternator rectifier diodes very
    seldom short, or if they do short, they promptly will internally burn open, ot
    destroy the alternator.

    The inverter generates a pulsed DC signal, feeding its output stages, which
    turn on and off in an approximation of a ac signal, But in reality is a square
    wave , made up of many sub and multiple harmonics of the fundemental
    60 hz output frequency. If the input voltage is not a clean DC voltage,
    other frequencies may be generated at the output, and if this is a good
    inverter, it will have a detection circuit that monitors the output frequency,
    and if it varies more than a cycle or two above or below the 60hz, the safety
    circuit will shut the inverter down, this to protect all downstream equipment.

    It is also possible to generate a combination of a number of frequencies
    by connecting the inverter directly in line with the alternator, A good
    battery will act as a filter to some extent, attempting to hold the DC
    voltage constant, but a good lo-pass filter might solve the problem, and
    prevent noise from the alternator from entering the dc front end of the inverter.
    On the output of the inverter, which is inherently electrically noisy, a filter
    network should be installed, again a lo-pass multi stage filter designed to
    pass 60 hz, and block or attenuate any frequency above the 60 hz.
    CORCOM makes any number of good multi stage filters, and is
    available from allied electronics, digi-key, jameco electronics, mouser,
    but avoid radio junk shack.
    Any DC wiring from the alternator, or the battery to an inverter needs to
    be protected by a circuit breaker of fuse, and must be at least a#12 wire, preferable a #10, to a #6 depending on the amp draw of the inverter.
    #12 is good to 20Amp, #10 to 30 amp, #8 to 45 amp, and #6 to
    60 amp. Your ground should be solid coper back to the battery negative
    connection to the vehicle frame. For optomim operation, all grounds
    should return to a common connection, thus preventing ground loops
    through the vehicle body, generating stray voltages and electrical
    noise.
    Digital and switching equipment is inheraently electrically noisy, and
    noise suppression and signal conditioning techniques must be employed
    to prevent headaches.

    Normal vehicle batteries are not designed for continious low current loads, but to provide a large current to spin up the starter starting the car.
    On the other hand, marine deep cycle batteries are designed to carry a
    light load for a long time, and are very limited in providing high aperage
    cranking currents.
    This is the reason for dual battery system, along with being isolated from
    each other, but charging through a diode pair, from a single source.
    vehicle battery is standard, and the battery powering electronics is a deep
    cycle system.

    If you put a large capacitor across your battery, put a fuse or breaker
    between the battery and the cap, might save your vehicle if the cap
    were to decide to short.. caps explode when shorted internally and
    voltage is left applied.

    12 VDC is fun to work with, can feel it when you get your fingers across
    it, but does not shock you. Since it is 12vdc, most devices draw a fairly
    large current at 12vdc. Thusly, a 12 volt battery system may have
    upwards of 200 amps available at the point of short circuit. this may
    not shock, but will cause almost instanious heating of wires, and will start fires. Please do spend the time to install fuses or circuit breakers in all
    circuits tied to a battery source.

    Any installation of a large capactor to fill in max current spikes, must be done
    as close as possible to the load, Do not place it near the alternator, or
    you may experience very erratic alternator voltage regulation, as the capacitor may try and keep the alternator field at a high voltage, when
    the regulator is trying to lower the alternator output voltage.


    Viking mobile electronics.

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