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Charging with powersupply @ 14.65v

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  • Charging with powersupply @ 14.65v

    I've seen an example of charging a battery with a 30A power supply . He claims that the max output current is limited to +/- 30A @ 14.65V. See attached pict.

    Voltage range 10v-14.95v, no current limit trimpot.

    Question:
    Can I then assume that the output is "always" limited to +/- 30A max, even when the battery SoC is e.g. 12v with charge voltage 14v+ , no "poof" when start charging @ low SoC ?
    Attached Files

  • #2
    You need a sturdy power supply that has internal current limiting. That is what prevents too much current (amps) going to a low battery. Cheap power supplies might be "rated" at 30A, but that is not the same as a supply with current limit settings, which would be fine for days, putting 30A into a dead short.

    The only way to force more current, is to increase the voltage, which is not recommended. As the battery charges, the 30A will slowly reduce as the battery is no longer accepting that much.
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    • #3
      Originally posted by GeorgeF View Post
      ..........

      Question:
      Can I then assume that the output is "always" limited to +/- 30A max, even when the battery SoC is e.g. 12v with charge voltage 14v+ , no "poof" when start charging @ low SoC ?
      I am not sure who the "he" is that you refer to in your question. I don't assume what people tell me is the truth until I verify.
      Normally you should be able to rely on the manufacturers rating but it never hurts to check that assumption with your own tools, especially in distant parts of the globe with unknown vendors.
      Last edited by Ampster; 02-16-2022, 12:04 PM.
      9 kW solar. Driving EVs since 2012

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      • #4
        Originally posted by GeorgeF View Post
        I've seen an example of charging a battery with a 30A power supply . He claims that the max output current is limited to +/- 30A @ 14.65V. See attached pict.

        Voltage range 10v-14.95v, no current limit trimpot.

        Question:
        Can I then assume that the output is "always" limited to +/- 30A max, even when the battery SoC is e.g. 12v with charge voltage 14v+ , no "poof" when start charging @ low SoC ?
        Is that a charger that people use in RV's? I have one made by IOTA rated 50Amps and it performs a 3 level charge for my coach batteries.

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        • #5
          Originally posted by SunEagle View Post
          Is that a charger that people use in RV's? I have one made by IOTA rated 50Amps and it performs a 3 level charge for my coach batteries.
          I think the example above is just a cheap power supply.

          I've been reading some old posts here. See attachement.

          My question is in fact: is every powersupply with adjustable voltage suitable for charging a battery?
          Attached Files

          Comment


          • #6
            Originally posted by GeorgeF View Post
            .......

            My question is in fact: is every powersupply with adjustable voltage suitable for charging a battery?
            New question, new answer, but the answer above still applies. As mentioned above it is important that the power supply be current limited. Not every power supply meets that spec,

            Secondly for Lithium it is important that the power supply actually shut off when voltage and current reach settings. With Pb a power supply that provides small current or trickle charge could work.
            9 kW solar. Driving EVs since 2012

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            • #7
              Originally posted by Ampster View Post
              New question, new answer, but the answer above still applies. As mentioned above it is important that the power supply be current limited. Not every power supply meets that spec,

              Secondly for Lithium it is important that the power supply actually shut off when voltage and current reach settings. With Pb a power supply that provides small current or trickle charge could work.
              A simple voltage supply usually is not a good match to a battery charging
              requirement. A battery might draw a rather large surge, and some supplies
              can be damaged if current limiting is not built in. Bruce Roe

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              • #8
                Originally posted by Ampster View Post
                New question, new answer, but the answer above still applies. As mentioned above it is important that the power supply be current limited. Not every power supply meets that spec,

                Secondly for Lithium it is important that the power supply actually shut off when voltage and current reach settings. With Pb a power supply that provides small current or trickle charge could work.
                I can't follow you. Usually lithium one charges @ < bms cut-off voltage. You then can float.
                ​​

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                • #9
                  Originally posted by GeorgeF View Post

                  I can't follow you. Usually lithium one charges @ < bms cut-off voltage. You then can float.
                  ​​
                  Most power supplies do not have an adjustable float voltage. It is irrelevant for you but I wanted other readers to understand that. Lithium cells suffer from shorter life if kept at higher voltage for a long time.
                  9 kW solar. Driving EVs since 2012

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                  • #10
                    Originally posted by Ampster View Post

                    Most power supplies do not have an adjustable float voltage. It is irrelevant for you but I wanted other readers to understand that. Lithium cells suffer from shorter life if kept at higher voltage for a long time.
                    I agree. From what I am familiar with my LiPO RC batteries are not to be charged to 100% if I plan on keeping them on the shelf for a while. Li will suffer if they are kept at a high float charge so my charger will stop at the point they are told to as compared to a FLA type battery charger which will continue to keep a float charge on them.

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                    • #11
                      Originally posted by Ampster View Post

                      Most power supplies do not have an adjustable float voltage. It is irrelevant for you but I wanted other readers to understand that. Lithium cells suffer from shorter life if kept at higher voltage for a long time.
                      If you CV-FloatCharge lithium @ e.g. 80% SoC you dont need adjustable voltage.

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                      • #12
                        I charge and float my RV’s lithium batteries at 3.475 per cell with 3.65 being the max per cell, so this makes the batteries about 90-95% charged. I can sometimes look at the battery monitor and see 0 amps going into or out of the battery, and have to go into the SCC to monitor what the total power consumption is. The parasitic draw on the RV may be 15 watts.

                        It took a bit of adjustment on the voltage setting, but there is a sweet spot. A different much smaller battery bank I built, my bulk charge is higher than the float, so the “personality” of the battery is different.

                        So at those settings the battery is neither charging or discharging, but “floating where its at. When I had FLA, I don’t remember exactly, but I do remember a constant amperage going into the batteries and not the 0 amps I see with Lithium.

                        For the summer months, when I won’t use the RV for Four months, I will shut the battery off at between 50%-70% SOC.

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