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    Battery - Controller calculations

    If connect two 56v batteries in a series to a 72v controller, will this over load the controller?

    #2
    Almost certainly

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      #3
      Originally posted by rfryda View Post
      If connect two 56v batteries in a series to a 72v controller, will this over load the controller?
      If the controller has Infineon MOSFETs, a 72V controller would likely have 4110 FETs which are rated up to 100V https://www.infineon.com/dgdl/irfb41...535615a9571e0b.

      A controller for voltages between 100 and 150V with Infineon FETs will likely have 4115 FETs which are rated up to 150V https://www.infineon.com/dgdl/irfb41...535615ba6a1e0f.

      A corollary of this 100V maximum rating for 4110 FETs is that one cannot use a 96V battery for a system with a 4110 controller because a fully charged 96V battery will be approximately 112.1V which far exceeds the 100V upper limit.
      Last edited by commuter ebikes; 09-08-2018, 08:28 PM.

      Comment


        #4
        It's not just the MOSFET's you have to be concerned with.

        I'm a little confused by the reference to Infineon - maybe I missed something. I don't know what difference the manufacturer alone is going to make to the MOSFET specifications.. Infineon, International Rectifier, ON, etc. all make MOSFET's for all kinds of voltages, RDS(on)'s, etc. that are suitable for this application and it's not optimal to use a higher voltage MOSFET than necessary for an application since it will cause other parameters like gate charge to negatively impact the MOSFET performance. FYI RDS(on) is just one parameter that affects the power dissipation - at these voltages and currents gate charge is a parameter that can have a significant effect on dissipation - it depends on how fast they are switching. Granted at any given moment in time there may be an optimal MOSFET from a given manufacturer that is optimal in terms of performance and cost for a given application and this application there are only a few that are appropriate, but give it a year and it will be different...

        Comment


          #5
          Originally posted by AZguy View Post
          It's not just the MOSFET's you have to be concerned with.

          I'm a little confused by the reference to Infineon - maybe I missed something. I don't know what difference the manufacturer alone is going to make to the MOSFET specifications.. Infineon, International Rectifier, ON, etc. all make MOSFET's for all kinds of voltages, RDS(on)'s, etc. that are suitable for this application and it's not optimal to use a higher voltage MOSFET than necessary for an application since it will cause other parameters like gate charge to negatively impact the MOSFET performance. FYI RDS(on) is just one parameter that affects the power dissipation - at these voltages and currents gate charge is a parameter that can have a significant effect on dissipation - it depends on how fast they are switching. Granted at any given moment in time there may be an optimal MOSFET from a given manufacturer that is optimal in terms of performance and cost for a given application and this application there are only a few that are appropriate, but give it a year and it will be different...
          I posted that because I was once exchanging emails with Edward Lyen with the idea of using a 96V battery with his 72V controller. What I posted was paraphrasing his response.

          Comment


            #6
            I see. I'm not up on which controllers are using which MOSFET's - as I was trying to point out though, it's a dynamic market space and what was true a year or two ago may not be what's true today and is unlikely to be true in the not-too-distant...

            To the OP question I don't think putting >100V on whatever controller (he never did specify which one) this is would be a good idea and there are more than just output MOSFET's to be concerned with...

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