Roban - World Class Scale Helicopters

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Charging Time?

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  • Charging Time?

    Just bought the HobbyZone RC Airplane Carbon Cub S 2 1.3m Ready-to-Fly with
    Spektrum 2200mAh 3S 11.1V Smart LiPo Battery
    Spektrum S120 USB-C Smart Charger

    I've got the charger plugged into a USB port on my computer and it's been flashing double flashes of purple light for hours. How long should charging take?

  • #2
    According to the manual your power supply determines the charging amps. The manual also says a double purple flash means the battery is between 25%-75% charged.

    What is the power rating of your power supply and the USB port? If it's pretty low it could take awhile.


    • #3
      Typically a USB port on a PC puts out about 0.5A, with some powered external USB ports putting out about 1A. Occasionally, you might find one that puts out 2A. Charging a 2200mah LiPo from a USB port is a painfully sloooooowwwww way to charge. It could take most of the day or overnight, but that’s not safe to leave any LiPo charge unattended. Better to get even the cheapest AC balance charger.
      Can a USB charger even balance charge?


      • #4
        I finally unplugged from the computer last night and plugged it into the built-in USB outlet on the kitchen island. It finally went to three flashing purple lights before I unplugged and went to bed. This morning I plugged it back in and it finally went to a solid green light.

        Starting to charge the 2nd battery now. I just didn't expect it to take so long and especially since you aren't supposed to leave it unattended or let it charge overnight, etc.


        • #5
          How should a 4cell lipo read on the screen win it's fully charged 4.20 or 4.02?


          • #6
            Originally posted by Mike mitchell View Post
            How should a 4cell lipo read on the screen win it's fully charged 4.20 or 4.02?
            4.2v/cell or 16.8v total.


            • #7
              4.02 or 4.20 for4s?


              • #8
                You must be very new at this. A LiPo battery fully charges to 4.2 volts per cell, regardless of how many cells it has. Since it's a 4 cell battery, that's 4.2 volts times 4 cells, or a total of 16.8 volts for the whole thing. Do you not understand that 4.2 is the same as 4.20? That is simple math expression in decimals.