Lead acid battery desulfator..

Discussion in 'The Projects Forum' started by roltex_rohit123, Mar 26, 2010.

  1. roltex_rohit123

    Thread Starter Member

    Jan 1, 2010
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    I am working on lead acid battery desulfators from a long time. I have surfed the internet much about it but mot found any thing that could help or guide me. all I read about batteries is that most batteries die out because of the sulfation in them. I worked with battery chemistry but the thing annoying me was that, the desulfators are sometimes criticized or sometimes they are appreciated. i have developed a new model which could answer most of the questions but i need to simulate it. can anyone tell me a good software to simulate it? or can anyone simulate one for me?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Have you looked at Linear Technology's free LTSpice software?

    It's quite good, and completely free. Google "LTSpice download"

    There is a support group for LTSpice on Yahoo! Groups; here:
    http://tech.groups.yahoo.com/group/LTspice/
    Join it.

    Some poo-pooh the idea of desulfators.

    If a battery is in reasonably good condition, simply applying an equalization charge at periodic intervals will be sufficient to keep the sulfation at bay, and the battery in good condition.

    However, I've found that some batteries that are very heavily sulfated don't respond very well to equalization charges, particularly if the specific gravity reading between cells varies significantly.

    Equalization charges are not good for gel-cells, as bubbles can form in the electrolyte gel; this will permanently reduce their capacity.

    If a standard wet lead-acid cell has a high differential of specific gravity between cells, applying an equalization charge may damage the "good" cells due to the high temperatures generated.

    A desulfator circuit is quite a bit more gentle; it does not require high battery currents. Agitating a wet-cell battery periodically while using a desulfator and trickle charger helps to mix the electrolyte up.

    I'm using an N-channel version of Alistair's original design; it has a trickle charge circuit, peak voltage and average voltage test points added.
     
  3. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    What kind of simulation are you looking for.
    And Posting the schema is also a good idea.
     
  4. SgtWookie

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    Why don't you post your circuit for starters?
     
  5. roltex_rohit123

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    Jan 1, 2010
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    http://i820.photobucket.com/albums/zz124/rohitdhamal/Desulfator4046.jpg
    this is my circuit. It may not be flawless because i'm not a electronics professional, but a life science professional. but i have hobby contructing electronic projects. so i just starrted with this one. the central idea is that it sends diferent frequencies within its range into the battery and adjusts itself at the frequency of sulfate crystals. then it locks itself to it and in the state ofcharging converts sulfate back to acid and lead. but i dont have technical knowledge but have concern over environmental issues and life. so i work on circuits like these. will someone help me out?

    About simulation, LT spice does not have MM74HC4046 simulation and dont know how to construct it.
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    Be sure to check the Yahoo groups LTSpice Group. They have tons of models. You have to sign up, but it is one of the best groups to be involved in. (Besides AAC) ;)

    Sgt.Wookies post above has the link to the LTSpice YahooGroups. Take a look there.
     
  7. R!f@@

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    Apr 2, 2009
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    Ur circuitry does not work.
    I also did not have that 4046, so I tried with another PLL.
    With 100Hz to1KHz at 1V rms. The out put shows no sign of pulsing whatsoever, but just a steady 12V.
    The MOSFET is not switching. I think the biasing is wrong
     
    Last edited: Apr 1, 2010
  8. SgtWookie

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    Jul 17, 2007
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    It looks like you've used an IRF9Z34 in your schematic.
    Since the 4046 is powered by 5V, there's no way for it to raise the gate of the MOSFET to 12v in order to turn it off.
     
  9. R!f@@

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    Yea !! that was the issue.
    The PM requested me to simulate his circuit, so I didn't bother as much as checking and changing the components except the PLL.
    Sorry . My bad..
     
  10. roltex_rohit123

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    Jan 1, 2010
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    What would be the ideal way to make it work? what components should be used and how should the circuit be modified to make it work?
     
  11. t06afre

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    May 11, 2009
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    Your circuit looks like a variant of the circuit made by Ron Ingraham(http://home.comcast.net/~ddenhardt201263/desulfator/n_channel_schem.gif) Found on many sites such as this http://home.comcast.net/~ddenhardt201263/desulfator/lowpower.htm
    It is somewhat hard to simulate this circuit, I think the best thing is to use an oscilloscope and measure the current spike by inserting a small resistor say 0.1 ohm. then you can try to fine tune your circuit. My last link also have a good discussion about the desulfator inner workings. But feel free post again if you want some help in this project
     
  12. roltex_rohit123

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    Jan 1, 2010
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    is there something wrong in the circuit? If irf9z34 is not switching then what could replace it? and what could be done to make it work? this is my first project and i cant let it die like that. could any one help me? well, i again give give the central theme of it. this circuit is build to send pulses from 1 MHz-4MHz. with every pulse it sends in the battery, it tunes itself to the frequency of the sulphate crystals. the frequency is 3.26MHz. within no time it tunes itself to this frequency( done by the demodulator PLL). then it locks on this frequency and keeps pulsing the battery. At the same time we charge the battery, which gives the energy to break these crystals. ultimately the battery is charging and getting rid of the sulphate. there's a bit of chemistry here, but i think those who wish to help me should bother least of it, since i'm a good at chemistry than electronics.
     
  13. t06afre

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    One important future of the circuit you posted is the charcging and decharging of the 100uF 16V capacitor. Are you sure you can do that at 1-4 Mhz.
     
  14. SgtWookie

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    It's not really practical to use a PLL to drive the gate of a power MOSFET at such high frequencies.

    I don't put much stock in the claims of resonant frequencies being more effective, as the crystals are going to be of different sizes as they are re-dissolved into the electrolyte.

    The L of the inductor and C of the plates (plus the parasitic L and C of the conductors) are going to be the determining factors on how the circuit "rings" after the MOSFET's current is cut off.

    With the original Alistair design, the 220uH inductor is "charged" until saturated (in many cases, well beyond saturation); when the MOSFET turns off, you get a big spike to the battery. That rings on for a brief period of time.

    One has to adjust the timing values for the particular components used. I decreased both the MOSFET ON time and OFF times; I have a much higher PRF than the standard circuit, and have adjusted the MOSFET on time so that the inductor just enters saturation.

    If you try to continue with your experiment, you'll likely run into problems with "flux walking" which will blow out your transformer.

    It'll be tough to drive a power MOSFET at that high of a frequency anyway.
     
  15. t06afre

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    Did you read the link i sent you. As I think I said you will find a good explanation of the inner workings. On this page the author say one current spike will last for about 100 useconds. And this cycle will indeed limit your pulse frequency far below 1 MHz. And also have in mind that system must have time to "recharge" to the energy level that is used used in the latter spike.
    [​IMG]
     
    Last edited: Apr 2, 2010
  16. roltex_rohit123

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    Jan 1, 2010
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    so what should i do next? i need to send the pulses at that very frequency by my calculations. there's a more chemistry than electronics in that. in the other models the frequency that they use only loosens the sulfate particles and make them fall off. it is good for some time as battery starts working, but this reduces the overall material from the plates and in due course of time it proves harmful, as the plates fall off and cells get shorted. my model intends to break sulphate to lead and acid. lead goes back to the plates or conducting surface and life is extended in true sense.
     
  17. roltex_rohit123

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    Jan 1, 2010
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    anybody there to help??
     
  18. retched

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    You will need more than one firing unit if you wish to put continuous pulses of those magnitudes into the battery. It will take far to long for each unit to recover to have the next pulse ready at that speed. You would require at least two firing sources and a mighty accurate triggering source to charge, fire, charge, fire in 3.96 MHz intervals.

    Now due to the 100uS lengths of the current spikes, your second source could cancel out or cause amplitude multiplication upon collision. Now that may or may not matter because during that "tuned" spike, it would change to millions of different frequencies as it rattled the millions of different sized crystals and lead plates in the mix.

    If you had one sulfate crystal in a clean water bath, found the resonant frequency of that crystal with its size, and attacked it with such current spikes, you likely would eliminate it. But due to the ever changing sauce the sulfate crystals are found in, it would make no sense to play a tuned frequency into the blend. You would likely do less to break them up than if you used lower frequency pulses whose echoes and reverberations through existing sulfate crystals would produce adequate higher frequencies to cause the resulting or desired reincorporation.

    [ed]

    What you may consider is an ultrasonic vibration bath on the battery during the desulfination process to see if the agitation moves the process along.

    [/ed]
     
    Last edited: Apr 3, 2010
  19. SgtWookie

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    Jul 17, 2007
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    Actually, you would need either an H-bridge or a center-tapped primary of a toroidal transformer that could operate with decent Q in that frequency range. The secondary would provide the pulse.

    Such a toroid would be something like Amidon's Material #2, that has decent Q in the 3MHz range, depending upon the toroid size and number of windings.

    But, you'd never be able to get current supplied via 12v flowing through a 100uH inductor in the 3MHz range. The inductance would have to be reduced considerably.

    I simply don't have the time to fiddle around with something like that, and don't happen to have any toroids made from suitable material on hand.
     
  20. R!f@@

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    Apr 2, 2009
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    I am surprised, I never realized you have such an insight on battery chemistry.
    I will contact you when I decide to make a de-sulphator.....count on it, u too Sgt.
     
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