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Thread: Idea for cell, maybe...

  1. #1
    fisher Guest

    Idea for cell, maybe...

    You have to know a bit about electronics in order to understand what Im about to say, but...

    What if you made 10 or 12 separate cells, each consisting of only two plates, each wired +-, each in separate housings so that they worked independently of each other. BUT, wire them in series. So that voltage goes into one plate of the first cell, then the wire from the other plate goes to the next cell, and so on.

    This would be equavilent to wiring a cell with several neutral plates, each (if there were 10) would get about 1.4 volts each, (with 14 volts applied.)

    Now, why have separate cells? As a cell heats up, it's resistance decreases. If you understand series circuits, you know that less resistance, gets less voltage. So assuming that all cells are equal, each cell of ten with 14 volts applied would get 1.4 volts. But as one particular cell began to heat up, it's resistance would decline, consequently it's voltage would decline, causing more voltage to be applied to the colder cells, warming them faster. The hotter cell would get less voltage, enabling it to cool somewhat.

    That is the theory, what do you think? Actually, my idea is to have all cells tied together at the bottom so that I don't have to fill each separately, and the air lines exiting the top would connect them together there, but each should pretty much retain it's own water during operation, allowing temperature fuluctuations to cause voltage fluctuations, regulating temperature somewhat. (I hope.)

  2. #2
    Riddler250 Guest
    Quote Originally Posted by fisher View Post

    Now, why have separate cells? As a cell heats up, it's resistance decreases.
    Isnt it the other way around? resistance=heat and heat = resistance? A 16ga wire with a load of 20a would get hotter than 12ga wire with the same load

  3. #3
    Join Date
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    yeah, the series is the optimum way to go, but takes up about twice the space.
    1982 MB 300D Turbo Diesel 90%WVO/10%RUG + additives blend. $.50/gal
    don't know what MPG is, probly low 20s

  4. #4
    fisher Guest
    Riddler, we are talking about two different things here. For a wire, bigger wire can handle more current without heating.

    But for cells, as a cell heats, it's current increases, which tells me that it's resistance decreased. Think of water flowing through a pipe with a valve. Open the valve wide open, maximum current (flow) due to low restriction (resistance) in the pipe. Close the valve halfway, reduced current due to higher resistance to water flow through the valve.

    A bigger wire is a bigger pipe. More current can flow. That is why bigger wire can handle more current.

    Resistance does not equal heat. Current equals heat in that more current (in a cell or in a wire) creates more heat. More resistance decreases current, reducing heat.

    Clear as mud.

    BTW, Im a college electronics instructor. I have splained this before (or at least tried to) on numerous occasions.

  5. #5
    Riddler250 Guest
    Quote Originally Posted by fisher View Post
    Riddler, we are talking about two different things here. For a wire, bigger wire can handle more current without heating.

    But for cells, as a cell heats, it's current increases, which tells me that it's resistance decreased. Think of water flowing through a pipe with a valve. Open the valve wide open, maximum current (flow) due to low restriction (resistance) in the pipe. Close the valve halfway, reduced current due to higher resistance to water flow through the valve.

    A bigger wire is a bigger pipe. More current can flow. That is why bigger wire can handle more current.

    Resistance does not equal heat. Current equals heat in that more current (in a cell or in a wire) creates more heat. More resistance decreases current, reducing heat.

    Clear as mud.

    BTW, Im a college electronics instructor. I have splained this before (or at least tried to) on numerous occasions.
    I mean no disrespect but what about joule's law, that states H (Heat) = I2 (Current squared) x R (Resistance) x T (Time the current is allowed to flow).

  6. #6
    fisher Guest
    My best answer is to show you an example.
    Heat = I^2*R*T

    So lets say we run a generator at 12 volts, for one hour, and it has 4 ohms of resistance. The current will be 3 amps for this circuit. (If you know electronics I (current) = V (voltage) divided by R (resistance).
    So a 12 volt power supply with 4 ohms of resistance would pull 3 amps because 12 volts divided by 4 ohms = 3 amps.

    Heat = 3 amps ^2 * 4 ohms * 1 hour.
    Heat = 9 * 4 * 1
    Heat = 36 Joules.

    Now, lets decrease the resistance to only 2 ohms, half of the previous value.
    Using Ohm's law, the current in the circuit must be 6 amps.
    12 volts divided by 2 ohms = 6 amps.

    Now lets calculate the heat for the same voltage and time, but at half resistance of the original value, (which gives double current of the original value).

    Heat = I^2 * R * T
    Heat = 6 amps ^2 * 2 ohms * 1 hour.
    Heat = 36 * 2 * 1
    Heat = 72 Joules

    So doubling the current (halving the resistance) doubled the heat generated.

    I am not sure if I made the point but I am enjoying the discussion so let me know.

  7. #7
    Riddler250 Guest
    Quote Originally Posted by fisher View Post
    My best answer is to show you an example.
    Heat = I^2*R*T

    So lets say we run a generator at 12 volts, for one hour, and it has 4 ohms of resistance. The current will be 3 amps for this circuit. (If you know electronics I (current) = V (voltage) divided by R (resistance).
    So a 12 volt power supply with 4 ohms of resistance would pull 3 amps because 12 volts divided by 4 ohms = 3 amps.

    Heat = 3 amps ^2 * 4 ohms * 1 hour.
    Heat = 9 * 4 * 1
    Heat = 36 Joules.

    Now, lets decrease the resistance to only 2 ohms, half of the previous value.
    Using Ohm's law, the current in the circuit must be 6 amps.
    12 volts divided by 2 ohms = 6 amps.

    Now lets calculate the heat for the same voltage and time, but at half resistance of the original value, (which gives double current of the original value).

    Heat = I^2 * R * T
    Heat = 6 amps ^2 * 2 ohms * 1 hour.
    Heat = 36 * 2 * 1
    Heat = 72 Joules

    So doubling the current (halving the resistance) doubled the heat generated.

    I am not sure if I made the point but I am enjoying the discussion so let me know.
    I am thinking in terms of most conductors used in electronics with a positive temperature coefficient. For what you to say to be corect, then stainless would have a negative temperature coefficient (increasing heat lowers resistance). Ive actually only been a tech for a few years, so there is still a lot to learn, but im pretty confident in what i know. After scooterdog its nice to have a professional discussion.

  8. #8
    Riddler250 Guest
    Quote Originally Posted by fisher View Post
    Riddler, we are talking about two different things here. For a wire, bigger wire can handle more current without heating.

    But for cells, as a cell heats, it's current increases, which tells me that it's resistance decreased. Think of water flowing through a pipe with a valve. Open the valve wide open, maximum current (flow) due to low restriction (resistance) in the pipe. Close the valve halfway, reduced current due to higher resistance to water flow through the valve. .
    I havnt built a cell yet, so I havnt witnessed it reaction to heat or resistance.

  9. #9
    Join Date
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    Wink

    Quote Originally Posted by Riddler250 View Post
    I havnt built a cell yet, so I havnt witnessed it reaction to heat or resistance.

    As the cell temperature rises, the electrolyte resistance lowers.

    That is the reason for cell runaway and the necessity for PWM.

    BoyntonStu

  10. #10
    Riddler250 Guest
    Ive seen a lot about the pwm, but for some reason always skip over it in the posts. But i am on this forum to learn about hho from those who know. I actually have a smacks booster built but havnt powered it up yet, as soon as i built it, i read smiths and painless's threads and decided to go a different route, maybe i can get it started this week, and see first hand how these operate.

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