2000mm Giant Scale B-24 - Olive Drab

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Battery Voltage

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  • Battery Voltage

    What is the lowest battery voltage I can flight without damaging the batteries or having problems with the plane?

  • #2
    Re: Battery Voltage

    I shoot for 3.75V per cell. Ideally you want 3.8V per cell but I usually end up at 3.75. This is resting voltage after the plane has landed. Your LiPo will see far lower per cell voltages under load.

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    • #3
      Re: Battery Voltage

      Thank you, big help.

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      • #4
        Re: Battery Voltage

        Let me know if I'm mistaken, but my understanding is that 3.8v-4v is a fully charged lipo cell and 3v is the minimum safe voltage. Thanks The Doctor

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        • #5
          Re: Battery Voltage

          Unloaded and rested, 3.7V is about 20% charge, 3.8V is about 40%, and 4.2V is full charge (actually ~4.23V-4.25V, but you risk damage there). Storage charge is suggested to be 3.8V-3.9V, to maximize battery life. Minimum voltage under load, of course, depends on how many amps are drawn, but shouldn't go below about 3.0V at high currents, 3.3V at moderate currents, relative to the C rating. For longest battery life, you shouldn't discharge below 20%, and never, ever, overcharge.

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          • #6
            Re: Battery Voltage

            Thanks! I think this will clear this for a lot of RC pilots. The Doctor

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            • #7
              Re: Battery Voltage

              A web search will reveal much of this info, but much of what you find is rather stale, due to improvements in the chemistry. There are folks over at rcgroups who have studied batteries much more thoroughly than I, and keep their data fresh, which is mostly where I get my current data. Unfortunately, many ESCs are still programmed with a cutoff voltage for older batteries, and is too low for the current batteries, so a flight timer, and a charger that shows charge put back in, are your best bet for battery life and safety.

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              • #8
                Re: Battery Voltage

                This is very important and worth mentioning. Do not hit the LVC cutoff on your ESC. This will severely shorten the life of a LiPo.

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                • #9
                  Re: Battery Voltage

                  Tom, By "do not hit" are you talking about not running your LiPo down to the LVC? I presume so (no counter-logic available), and must say I find your supposition .... surprising?

                  First, the LVC is, on most 'better' ESC's anyway, a setting. Pick one higher than lowest LiPo per-cell Voltage recommendation. Available choices are usually purpose-driven. Choose wisely, if that needs saying.
                  And secondly, remember what an LVC does .. what it's <i>for!</i> It's a protective device.
                  eg, when it comes down to bringing down a $350 plane safely vs punishing & possibly toasting a $40 LiPo, guess who gets to play the Sacrificial Lamb?

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                  • #10
                    Re: Battery Voltage

                    Bringing down that $350 plane, dead-stick, can be a real problem, too, especially if it is a warbird. Use a timer, or remote sensing, and avoid a difficult landing, IMO.

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                    • #11
                      Re: Battery Voltage

                      The LVC is a great device to save a plane but it should never be relied on. When the LVC is set to the highest setting available for a LiPo, it is still too low and will raise internal resistance in the LiPo cells. Running a LiPo pack to LVC one can permanently damage a pack and doing this on a regular basis will severely shorten the life of a LiPo pack. I've tested this with many different brands of packs using packs of the same age with the same number of cycles as control (the control group does not hit LVC). The packs which hit LVC die an early death and IR increases.

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