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Smart Charger 29 volts @ 1 amp how do I change it 25 volts

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    Smart Charger 29 volts @ 1 amp how do I change it 25 volts

    I bought these chargers to charge 24 volt li-ion battery packs I could not find one that would be at 25 volts and the close I could come up with is this

    What resistors would I have to change to make it work at 25 volts not 29 volts

    The ic chip that is KTG3646 has a logo of ( IG ) I can not find a data sheet for it
    Attached Files
    Last edited by sam_sam_sam; 07-07-2019, 09:40 AM.
    9 PC LCD Monitor
    6 LCD Flat Screen TV
    30 Desk Top Switching Power Supply
    10 Battery Charger Switching Power Supply for Power Tool
    6 18v Lithium Battery Power Boards for Tool Battery Packs
    1 XBox 360 Switching Power Supply and M Board
    25 Servo Drives 220/460 3 Phase
    6 De-soldering Station Switching Power Supply 1 Power Supply
    1 Dell Mother Board
    15 Computer Power Supply
    1 HP Printer Supply & Control Board * lighting finished it *


    These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

    1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
    2 Hem Saw Computer Stack Board

    All of these had CAPs POOF
    All of the mosfet that are taken out by bad caps

    #2
    Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

    It's very cheap power supply - there is no opto-coupler+voltage reference (i.e. TL431) to provide feedback to the SMPS IC and control the DC output voltage.
    It might just regulate from the aux winding, not the output. That leaves only R5, R6 and the top resistor by EC2 to tinker with.
    In other words, it is regulating the voltage on EC2 which is proportional to Vout, on the mains side.
    The LM358 and all those parts are just for the LED. You'd have rto find the IC datasheet and sketch the schematic a little, but I would not use it for lithium ion battery charging because it will always have poor regulation and it's not really a 29W power supply. The parts would overheat.

    Comment


      #3
      Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

      Use a step down buck converter. That is the safest thing.

      Comment


        #4
        Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

        The ic maker is Kintago, This may or may not help
        Attached Files
        Last edited by R_J; 07-07-2019, 03:57 PM.

        Comment


          #5
          Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

          Originally posted by R_J View Post
          The ic maker is Kintago, This may or may not help
          Thank you for finding the data sheet for me it very hard to read the part number on the ic chip

          This is helps a lot at
          I now understand how this switching power supply is suppose to work

          From what I read it might not make a difference but I will have try it and see how it works

          Now what I could limit the current more than it is set to now this is just a thought at this point
          Last edited by sam_sam_sam; 07-07-2019, 06:36 PM.
          9 PC LCD Monitor
          6 LCD Flat Screen TV
          30 Desk Top Switching Power Supply
          10 Battery Charger Switching Power Supply for Power Tool
          6 18v Lithium Battery Power Boards for Tool Battery Packs
          1 XBox 360 Switching Power Supply and M Board
          25 Servo Drives 220/460 3 Phase
          6 De-soldering Station Switching Power Supply 1 Power Supply
          1 Dell Mother Board
          15 Computer Power Supply
          1 HP Printer Supply & Control Board * lighting finished it *


          These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

          1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
          2 Hem Saw Computer Stack Board

          All of these had CAPs POOF
          All of the mosfet that are taken out by bad caps

          Comment


            #6
            Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

            One note

            I would be charging these batteries with a BMS protection board
            9 PC LCD Monitor
            6 LCD Flat Screen TV
            30 Desk Top Switching Power Supply
            10 Battery Charger Switching Power Supply for Power Tool
            6 18v Lithium Battery Power Boards for Tool Battery Packs
            1 XBox 360 Switching Power Supply and M Board
            25 Servo Drives 220/460 3 Phase
            6 De-soldering Station Switching Power Supply 1 Power Supply
            1 Dell Mother Board
            15 Computer Power Supply
            1 HP Printer Supply & Control Board * lighting finished it *


            These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

            1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
            2 Hem Saw Computer Stack Board

            All of these had CAPs POOF
            All of the mosfet that are taken out by bad caps

            Comment


              #7
              Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

              If you could not read the numbers clearly, It could also be a KTG3546
              Attached Files

              Comment


                #8
                Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

                That 24 volt li-ion battery packs how are made?
                In most cases (for tools example) are in multiple of 3.6 or 3.7V
                18V ones are formed by 5 elements,
                3.6V x 5 elements = 18V
                but fully charged
                4.2V x 5 elements = 21V
                So depending on number of elements voltage may be higher than 24V

                Comment


                  #9
                  Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

                  It has 4.2 X 6 elements = 25.2 volts —> before the BMS protection board ends the charging cycle which is really 4.1 X 6 elements = 24.6 volts
                  Last edited by sam_sam_sam; 07-08-2019, 03:48 AM.
                  9 PC LCD Monitor
                  6 LCD Flat Screen TV
                  30 Desk Top Switching Power Supply
                  10 Battery Charger Switching Power Supply for Power Tool
                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                  1 XBox 360 Switching Power Supply and M Board
                  25 Servo Drives 220/460 3 Phase
                  6 De-soldering Station Switching Power Supply 1 Power Supply
                  1 Dell Mother Board
                  15 Computer Power Supply
                  1 HP Printer Supply & Control Board * lighting finished it *


                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                  2 Hem Saw Computer Stack Board

                  All of these had CAPs POOF
                  All of the mosfet that are taken out by bad caps

                  Comment


                    #10
                    Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

                    Originally posted by R_J View Post
                    If you could not read the numbers clearly, It could also be a KTG3546
                    You have the right part number the second digit was the one that I could not really make out for sure what it is
                    9 PC LCD Monitor
                    6 LCD Flat Screen TV
                    30 Desk Top Switching Power Supply
                    10 Battery Charger Switching Power Supply for Power Tool
                    6 18v Lithium Battery Power Boards for Tool Battery Packs
                    1 XBox 360 Switching Power Supply and M Board
                    25 Servo Drives 220/460 3 Phase
                    6 De-soldering Station Switching Power Supply 1 Power Supply
                    1 Dell Mother Board
                    15 Computer Power Supply
                    1 HP Printer Supply & Control Board * lighting finished it *


                    These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                    1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                    2 Hem Saw Computer Stack Board

                    All of these had CAPs POOF
                    All of the mosfet that are taken out by bad caps

                    Comment


                      #11
                      Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

                      Originally posted by redwire View Post
                      I would not use it for lithium ion battery charging because it will always have poor regulation and it's not really a 29W power supply. The parts would overheat.
                      I did run a test on this battery charger controller

                      On a scale of ONE board does not work at all TEN board works perfectly

                      I give it a 2.5 and this might be too high of a rating

                      Here is why

                      One note the battery voltage was at 3.3 volts per cell

                      Yes it will charge the batteries however after about five minutes the temperature of the case goes to a temperature of 128*F at this point I stopped the charging of the batteries

                      You were right about it would over heat but I want to test it myself and see just how bad it could get
                      Last edited by sam_sam_sam; 07-14-2019, 09:09 AM.
                      9 PC LCD Monitor
                      6 LCD Flat Screen TV
                      30 Desk Top Switching Power Supply
                      10 Battery Charger Switching Power Supply for Power Tool
                      6 18v Lithium Battery Power Boards for Tool Battery Packs
                      1 XBox 360 Switching Power Supply and M Board
                      25 Servo Drives 220/460 3 Phase
                      6 De-soldering Station Switching Power Supply 1 Power Supply
                      1 Dell Mother Board
                      15 Computer Power Supply
                      1 HP Printer Supply & Control Board * lighting finished it *


                      These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                      1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                      2 Hem Saw Computer Stack Board

                      All of these had CAPs POOF
                      All of the mosfet that are taken out by bad caps

                      Comment


                        #12
                        Re: Smart Charger 29 volts @ 1 amp how do I change it 25 volts

                        Now I have found a way to use the secondary side of this power supply based on this reply

                        Originally posted by redwire View Post
                        The LM358 and all those parts are just for the LED.
                        I did have to add more resistance to LED lights circuit so the LED lights would not burn up
                        It only takes 10 milliamperes to active the current sensing circuit LED light and 0 milliamperes
                        for the other LED to be lighting

                        ( the circuit works at voltage of about 13 volts and higher to about 30 volts I think I read in the data sheet)

                        I cut the circuit board and separate the primary from the secondary and use that part of this circuit to let know when the battery pack is fully charged

                        The primary side of the circuit is going to used for a low level LED module but I have to work on this circuit when I have some time for this project
                        Last edited by sam_sam_sam; 07-14-2019, 06:02 PM.
                        9 PC LCD Monitor
                        6 LCD Flat Screen TV
                        30 Desk Top Switching Power Supply
                        10 Battery Charger Switching Power Supply for Power Tool
                        6 18v Lithium Battery Power Boards for Tool Battery Packs
                        1 XBox 360 Switching Power Supply and M Board
                        25 Servo Drives 220/460 3 Phase
                        6 De-soldering Station Switching Power Supply 1 Power Supply
                        1 Dell Mother Board
                        15 Computer Power Supply
                        1 HP Printer Supply & Control Board * lighting finished it *


                        These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                        1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                        2 Hem Saw Computer Stack Board

                        All of these had CAPs POOF
                        All of the mosfet that are taken out by bad caps

                        Comment

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