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I am working on a quadcopter project based on Arduino board, my system is powered by a 4S LiPo battery (14.8V) but the motors behave differently as the battery voltage drops, when discharging.

Is there any way that I can make the motors behave the same until a minimum value of, say, 5 volts?

My current system works fine at the range from 14.8 to 10 volts, but below that I can't even hover.

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STOP USING YOUR BATTERY IMMEDIATELY!

First of all you shouldn't let the voltage of a lipo battery drop below 3V per cell which in your case comes to 12V. Lipo Batteries are extremely dangerous and the way in which you are over-discharging it is one of the ways you definitely should NOT handle a lipo battery.

Please read the instructions given here completely before you start using your battery again -

http://www.dronethusiast.com/ultimate-drone-battery-care/

I don't want to scare you, but you should understand the various high-risk situations involved in using a lipo battery as part of a quadcopter.

Second, check for individual cell voltage of your lipo battery to make sure none of them are over-discharged.

This is the internal wiring of the lipo battery

Now, if their voltage is below 3V, be very careful as you might find links online to articles that claim they can help you 'restore' the lipo battery. An average lipo can take upto 500 recharge cycles and if you've been consistently over-discharging them their capacity will decrease; ie, recharge faster but drain faster.

If this is your first lipo battery, I suggest you get another one and handle it with care from start, or if your current battery is not damaged and all the cells attain nominal voltage, you can continue using it,

But first get a voltage indicator that visually displays the voltage reading on an 7-segment led display.

Take care... No seriously...Take care of the battery.

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  • $\begingroup$ As an aside, you can add a portion of code in the arduino that compensates for voltage drop WITHIN the prescribed voltage range ie. 12V to 14.8V using a voltage divider circuit fed to an analog pin on the arduino; and increase the throttle accordingly (with a factor of course). $\endgroup$
    – WizardOfRobots
    May 7, 2016 at 20:30
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    $\begingroup$ Good answer. Here is a recent question about LiPo batteries from Electrical Engineering Stackexchange. Might be useful. Also four fully charged LiPo cell in series will give 4 x 4.2 = 16.8 V. $\endgroup$
    – Bence Kaulics
    May 7, 2016 at 21:20

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