LiPo charger

Very new to copter flying. How on earth do I keep the batteries at half charge? I have a 3dr iris that came with a lipo charger.

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    • Eric, what I'm saying is try not to use more than 80% of your battery's capacity. That's different than 80% being left - it would be 20% left. But as Gary Mortimer mentions, in the long run using a timer works really well for most applications. As Francis Chan mentions, setting a timer so it runs whenever the throttle is above zero is the way to go, many transmitters support that.

      To get started, set the timer for a very conservative time, say 6 or 7 minutes. After the flight make a note of the actual flight time. Then when recharging the battery make a note of how much went back into it (all decent chargers will give you that figure). Now divide that number by the number of minutes flown. That gives you your average consumption per minute. Divide that number into 80% of the battery's capacity, and you now have the number of flight minutes available. Set your timer to that number and set an alarm to sound 30 seconds earlier.

      An example: You are flying a 5000 MaH baqttery, so want to land when 4000 MaH (80%) has been consumed. Your test flight is 6.5 minutes and you put 2475 MaH back into the battery. So you used 381 MaH per minute. That means that you can fly for about 10.5 minutes on 4000 MaH.

      There are several reasons why this is a good way, if not the best way, to manage your flight times. Aside from avoiding surprise landings, not least among them is that you can keep an eye on how your equipment - and not just batteries - is performing. For example the exact effect of changing to different props, or changing payload, is easy to see. 

      You do need to keep in mind that flight times may vary depending on things like temperature extremes, wind conditions and flying style. In time you'll learn to compensate for such factors, as you'll see their effects when you charge the batteries. You do have that 20% buffer if necessary, but you should also keep the voltage monitoring system active as a final backup.

    • This is the information I needed the most, thank you!

    • The Iris will auto land (or should) when the battery voltage gets low.  I think it's around 10.5 volts.

      I leave Droid Planner on and very loud (I prefer this over Mission Planner), it normally tells me bat voltage and I land (or Iris will) before it drops too low.

      My flight time with only the short legs is roughly 8-10min.  I would recommend setting up the 3DR radio (google er9x manual) to turn on the timer when you throttle so you know roughly your air time.

      Also let your batteries cool before recharging; you probably read this as well if you got the 50% storage thing.

    • Moderator

      +1 On a timer I can't stand flying TX without them. I also never fly a multi without one of these 


      Yes there is telemetry but a loud noise works very well ;-)

  • For my 3dr Iris setup I went with a Hyperion 730i Net3 charger and converted an old HP server power supply for 12v following TJinTech HP Server PSU conversion.  You'll need to buy some 10-12awg silicon wire from hobbyking and a female banana plug to complete the conversion.  I also picked up a Hyperion Sentry battery voltage meter (a bit fancy, but what the heck).

    IMO, the lipo charger they provide is kinda crappy for the 3dr iris.  My charge time was ~2hr on the OEM charger, with the hyperion, it's 50min.

    Convert HP server power supply for RC use - TJinTech
    Home of TJinGuy's heli info
    • Thanks for the advice, will look into it!

  • I'm not the most experienced with Lipos, but to monitor the levels of the battery (when not hooked up) you can buy a little battery checker that plugs into the balance lead on the battery, that will tell you what the individual cell voltages are at. If you're trying to get battery ready for storage, just check the cell voltages a few times during charging (probably should completely disconnect the battery while doing this) and stop when you get to about 3.85v per cell. 

    That solution is far from ideal. You would be better served buying a better charger that can automatically bring the battery up to the right voltage.

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