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Solid State Charger Battery cycling without ICs

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  • Solid State Charger Battery cycling without ICs

    Hi guys

    I thought I'd share my circuit which has come about from a requirement of mine. Basically I am using a couple of 3kW UPS units as line interactive inverters. I wanted to use a solid state Bedini circuit with the batteries which could be left connected permanently. I have disabled the charging circuits in the UPSs.

    Basically, the circuit below uses two very low cost TL431 shunt regulators as voltage detectors. You can buy 20 for a couple of bucks off that auction website.



    I will setout the explanation based on my setup. My UPS uses a 48V bank.
    I am running a Bedini SSG circuit with no base diode and a 50ohm 50W resistor with 3 H-sync transistors and a quadfilar air core coil. It self resonates and uses 1.6A. I got the idea from Jetijs' solid state charger...thanks dude.

    Vset = 2.5 X [1 + R1/R2]

    R1 & R2 are setup for the TL431 LVD which is configured as a Low Voltage Detector. It will turn the Relay A on when voltage on the bank drops below 50V.

    R3 & R4 are setup for the TL431 OVD which is configured as a Over Voltage Detector. It will turn the Relay B on when voltage is on or over 55.2V.

    Vss is the power supply to the solid state charger circuit. In my case Im using a 19V laptop power supply.

    Charger Supply IN is the power input into the solid state circuit.

    Since the charger self resonates, it can be turned on and off without spinning any wheels.

    If you analyse the circuit, you will see Relay B is setup as a latching relay.

    Consider the scenarios:

    Battery voltage is below 50V.

    1) TL431 LVD turns Relay A ON and the charger gets power. TL431 OVD has its power disconnected at this point

    2) Voltage climbs to 50V. TL431 LVD turns Relay A OFF and TL431 OVD circuit gets power.

    3) Voltage reaches 55.2V TL431 OVD turns on Relay B and is latched ON. Charger stops getting power.

    4) At this point the charger is turned off.

    5) Voltage drops back to 50V over a couple of days or so...due to use and discharge..
    6) TL431 LVD turns on Relay A which "resets" TL431 OVD circuit releasing Relay B...

    The wonderful cycle continues...

    I hope this helps some others who are trying to re-use UPS inverters with Line interaction.

    Regards
    Gus

    EDIT: I've changed the upper voltage to 64V instead of 55.2V. it gives a higher standing voltage when the charger is off.
    Attached Files
    Last edited by radiant; 08-14-2012, 02:08 PM. Reason: Schematic update

  • #2
    Picture of my charger

    This is the charging circuit. It is a quadfilar AWG 21 550 turn on an air core bobbin 4" x 3.5" x 3/4 bore. 1 trigger 3 power circuits. 50ohm 7W resistor which can since been upgraded to a 50W resistor.

    Transistors are nice H-deflection from Tvs.

    Really robust circuit.

    Really fast charging using 19V 2A source for the 48V 50Ah bank.
    Attached Files

    Comment


    • #3
      Changes to circuit

      Ive been having some issues with Relay A fluttering a bit and sometimes not even turning off!...So Ive redesigned that stage of it.

      Not sure if anyone else is using this circuit but I am about to adapt it for a 24V bank soon and will post the resistor values.

      Circuit attached works on 48V bank now.
      Attached Files

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