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    18650 battery charging

    Built a 18650 battery, 30v BMS. I use a standard 1.5ah 36v wall charger but it cuts out at 40v for whatever reason. 36v battery, full charged at 42v. Not sure if its the bms or what?


    #2
    What measured voltage does the charger put out when there is no load on it?

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      #3
      Originally posted by hiiamwalter View Post
      Built a 18650 battery, 30v BMS. I use a standard 1.5ah 36v wall charger but it cuts out at 40v for whatever reason. 36v battery, full charged at 42v. Not sure if its the bms or what?
      I have four 36V 18650 batteries and seven chargers. Six of the chargers (sent with the batteries) charged to 42V (when the batteries were new).

      A friend gave me an older (differently branded) 36V charger that he had laying around and it only charged the 36V batteries to a bit over 40V (when the batteries were new).

      Did your charger ever charge this battery to 42V? How many cycles on your 36V battery? As my batteries age, they charge to lower fully charged voltages.

      Is your BMS balance charging the cells at the end of the charging process?
      Last edited by commuter ebikes; 03-31-2018, 06:27 PM.

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        #4
        Originally posted by commuter ebikes View Post

        I have four 36V 18650 batteries and seven chargers. Six of the chargers (sent with the batteries) charged to 42V (when the batteries were new).

        A friend gave me an older (differently branded) 36V charger that he had laying around and it only charged the 36V batteries to a bit over 40V (when the batteries were new).

        Did your charger ever charge this battery to 42V? How many cycles on your 36V battery? As my batteries age, they charge to lower fully charged voltages.

        Is your BMS balance charging the cells at the end of the charging process?
        I never charged the battery up to 42v. It has only charged it up to 40v since I built the battery.

        On the bms im not sure when it balances them, but it does balance the cells.

        The battery has had about 3 cycles on it.

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        • AZguy
          AZguy commented
          Editing a comment
          How confident are you that your voltmeter is that accurate? Guessing you are in the 200V range and 2V is 1% so if the voltmeter is only 1% accurate it could be whatever it's reading +/-2V... Many cheap ones hope for 1%...

          I guess I'm just saying be careful how you interpret things unless you know your meter is telling you truth...

        #5
        Originally posted by hiiamwalter View Post

        I never charged the battery up to 42v. It has only charged it up to 40v since I built the battery.

        On the bms im not sure when it balances them, but it does balance the cells.

        The battery has had about 3 cycles on it.
        I wonder what the final charged voltage would be if you tried a different brand of charger. I was surprised that the two different brands of chargers that I had yielded two different results.

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