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Thread: Creating CR2032 battery attachments. I have a couple quick questions.

  1. #11

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    You were talking about replacing a rechargable battery with a CR2032, presumably stacked in series or parallel. The rechargable cells are there for a reason and that is to store more charge and provide more current/voltage for the backup memory (3.7V+ for whatever machine it is) and last much much longer than lithium cells. Yes, RTC lithium cells provide a slow trickle current for the clock, but I thought you were talking about a memory backup battery that requires 3.7V. Once you add a diode to the 3V lithium cell, the voltage drops to around 2.7V then you have around 0.5V of use before the CR2032 cell reaches it's drop out voltage of 2.5V, not much good then is it ?

  2. #12
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    Quote Originally Posted by Nathanieltolb331 View Post
    On a series diode, would I used one of those between both common and voltage? So two separate ones, or just one on the voltage? I was surprised that what I did worked so well, honestly. None of my ideas when it comes to electronics usually work. XD
    Nathaniel, a diode blocks current in one direct only and acts like a small voltage drop in the other direction. You need to install it so it is between the plus (+) wire of your new cell holder so the cells can supply voltage/current to the plus contact of the external contacts. The negative lead of the cell holder goes to the minus contact of the external contacts directly. If mounted incorrectly the diode (ends reversed) will prevent the voltage from reaching the plus contact. Do a google search for pictures of the circuit. Diodes are marked with a band to ID which end is which.
    Crazy old guy with a basement full of Pentium 1 laptops and parts

  3. #13

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    The diode is only used to block the flow of cuurent going into the battery (if replacing a rechargable cell). You should look up how a diode functions as it is one of the most common electronics components alongside the resistor

  4. #14
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    If you want a hydraulic analogy, think of a diode as an electrical check valve. Can you put more than one in a line? Sure, with no real benefit.

  5. #15

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    Quote Originally Posted by Chuck(G) View Post
    If you want a hydraulic analogy, think of a diode as an electrical check valve. Can you put more than one in a line? Sure, with no real benefit.
    I would use your anology for a variable resistor, controlling the flow. Another anology for a diode would could be the one way traffic lane of a highway, traffic only flows in one direction and you would have to reverse to go the opposite direction. Same with a diode, you can reverse the diode to change the direction of current.

  6. #16

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    Thank you for all of the information everyone. It is really helpful. I will see if I can order some of the schottky diodes and see if that works with the 286 and 386. I will test it and come back and report what I find out.

    Regards,

    Nathan

  7. #17

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    Chuck(G): you state that you used a Shottky diode with the CR2032 battery supply and apparently attached it to the positive side. So, my question will this work for AT&T 6300 MB as well? Do you recall what Shottkey you used? I have a standard battery replacment for the 3 volt supply for the real time clock which is more like 3.6 volts with no doide at present. If the battery were to fail then my plan is to replace that battery with the CR2032 and diode.

  8. #18
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    I used a garden-variety 1N5817, I think. Forward drop is about 400 mv.

    You might also consider using a MOSFET blocking setup;, but it has the characteristic of very low forward drop. See here

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