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Thread: Temperatuer feedback pwm

  1. #21
    Join Date
    Jul 2008
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    Federalsburg, MD
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    1,538
    Awesome job!

    Sounds like a great idea for controlling thermal runaway. Just out of interest, does the circuit have a way of setting the max amps the circuit will put through the cell?
    2006 Dodge Ram 4.7L - 16.5 mpg stock
    My thread Painless Experiment in HHO

  2. #22
    Join Date
    Jul 2008
    Location
    Columbus Ohio
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    211

    Amp limit?

    Painless,

    No there is no amp limiting.

    What I intend to do is set the startup current with my electrolyte. It will be about twice the current that I normally run my generator.

    The circuit will drive the gen hard until it gets to setpoint temperature, then it will go into feedback pwm to maintain the temp..

    That way, the generator will put out max until setpoint, then will put out max it can without overheating the generator.

    Will start on the winter circuit tomorrow.

  3. #23
    overtaker Guest
    Ridelong, Thanks for sharing your time and knowledge with us. It is much appreciated.

  4. #24
    Join Date
    Jul 2008
    Location
    Columbus Ohio
    Posts
    211

    temperature feedback pwm

    All,

    Took a break, now I'm back.

    Cleaned up the bench, fired up the temp circuit. The lm34 output was way high.

    Took the probe out of the electrolyte. The hot melt keeping the electrolyte off the wiring in the ss tube fell off in my hand. Start tomorrow to find something to seal the end of the probe.

    I'm thinking of posting only the temperature feedback pwm portion of this project. When I finish, will post the winter heater circuit with the temp pwm combo with relay switching between the circuits.

  5. #25
    Join Date
    Jul 2008
    Location
    Columbus Ohio
    Posts
    211

    Temp pwm schematic

    All,

    Here is the link to the temperature feedback pwm.
    http://www.mikecramer.com/images/temp-pwm800.jpg

    This circuit oscillates about 1400 Hz.

    Will post the system with winter circuit when I finish it.

    B/M for this circuit:

    All Electronics parts:

    LM34 Cat# LM34DZ $2.50
    1 uf Cat# RM105 $1.00/4

    Digi-Key parts:

    5k pot CT2264-ND $1.51
    49.9k 49.9KXBK-ND .49/5
    5.11K 5.11KXBK-ND .49/5
    (2)25.5K 25.5KXBK-ND .49/5
    4.99K 4.99KXBK-ND .49/5
    200 OHM 200XBK-ND .49/5
    10 VOLT ZEN 1N5327BTPMSCT-ND $3.90/10
    FET IRL1404ZPBF-ND $3.67

  6. #26
    Join Date
    Sep 2008
    Location
    tuscaloosa,al
    Posts
    177
    so how hard would it be to add current limiting to the temp feedback.

    that way, you set your max amps, then run them until heat becomes an issue. My alternator is weak and I would like to see a pwm that implements both.

  7. #27
    Join Date
    Jul 2008
    Location
    Columbus Ohio
    Posts
    211

    Current limiting?

    resago,
    It wouldn't be that hard to add current limiting, but it seems redundant. You can adjust the electrolyte to set the max amps. Then let it run until the gen reaches set point temp. Then it will adjust the pwm to hold the gen at that temp.

  8. #28
    Join Date
    Jul 2008
    Location
    Columbus Ohio
    Posts
    211

    Temp feedback with winter circuit.

    All,
    Just finished testing the temperature feeedback with the winter circuit that turns on a heating element when the gen electrolyte gets below 39 deg F.

    Works exactly as designed, turns on heating element at 38.8 deg, and off at around 39.4.

    Now I have to find a heating device. Am looking at the USB cup heaters on EBAY. Anyone have a suggestion?

    Will post the circuit and a picture of my unit soon.

  9. #29
    Join Date
    Jul 2008
    Posts
    1,174

    Wink

    Quote Originally Posted by ridelong View Post
    All,
    Just finished testing the temperature feeedback with the winter circuit that turns on a heating element when the gen electrolyte gets below 39 deg F.

    Works exactly as designed, turns on heating element at 38.8 deg, and off at around 39.4.

    Now I have to find a heating device. Am looking at the USB cup heaters on EBAY. Anyone have a suggestion?

    Will post the circuit and a picture of my unit soon.
    Use the electrolyte as your heating element.

    Pump up the Voltage by shorting out a few plates, and heating will result.

    BoyntonStu

  10. #30
    Join Date
    Jul 2008
    Posts
    627
    Quote Originally Posted by BoyntonStu View Post
    Use the electrolyte as your heating element.

    Pump up the Voltage by shorting out a few plates, and heating will result.

    BoyntonStu
    This would work as long as you aren't trying to start a frozen car in the morning.
    --
    Some days I get the sinking feeling that Orwell was an optimist!

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