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I have a 3S1P 2.2A 50C battery for a drone that I build. I have a charger that looks like this:

enter image description here

https://www.alibaba.com/product-detail/RC-B3-AC-Lipo-Battery-Charger_60812527463.html

At first, when the battery was new, I pulled a solid 15-20 minutes of aggressive flight time but now, only 6 months later, it is getting only 3 minutes! I have charged it for like 5 hours and it reached 12.48 volts which is good but I think the charger doesn't put much current and when it hits 12V it just stops charging. This is just a guess. Can someone please help me with this. I don't have much of a budget so is there is a safe way for me to get more flight time, I am more than happy to hear it!

Specs: My drone is an F450 frame with 4 A2212 100kv motors and weighs a total of 4lbs. My props are 1045 props and I have 3S 30A ESCs! I am using an Arduino as a flight controller and the YMFC-AL firmware/code.

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TL;DR:

You probably need to get a new battery pack. Your current one is likely at the end of its life.


My guess is that your battery is just old and has reached the end of its useful lifetime. The fully-charged capacity, and by extension flight time, of all batteries decreases over time when charged and discharged repeatedly. This process is sped along by pulling large amounts of current from the battery like what is sometimes necessary for multirotor flight.

Your description of the slow charge rate after the battery reaches ~12V points to the battery being degraded. At 12V, a 3S battery pack is sitting at ~4.0V/cell. This means that the charger has likely entered the balance charging phase where it tries to equalize the voltage of all 3 cells in the pack and slowly bring them up to 4.2V/cell.

Well-worn batteries will take longer in the balance charging phase because the internal resistances of each cell in the pack (which generally increases during the battery's lifetime at different rates for each cell in the pack) are different, resulting in more energy and time that must be used to fully balance the pack.

Tips for Increasing the Lifetime of a LiPo Battery

Although you mentioned that you're not really on a tight budget, you're probably interested in how you can make your next battery packs last longer. Here are some of the more common things that cause wear:

  • Sustained and peak current draw:

    It's generally an excellent idea to avoid drawing excessive amounts of current from a battery. Full throttle punches are fun and sound amazing, but do contribute to accelerating the degradation of the battery, so maybe don't do them as often. :)

  • Charging beyond 4.2V/cell:

    LiPo batteries shouldn't be charged beyond their full capacity of 4.20V/cell. Aside from increasing the risk of spontaneous combustion, the increased cell voltage puts extra strain on the internals of the battery, which accelerates battery degradation. It's true that some specific variants of LiPo have higher full-capacity voltages, like LiHv with ~4.25V/cell, but the vast majority of LiPo cells shouldn't be charged beyond 4.20V/cell.

  • Not storing packs at ~1/2 capacity (~3.7-2.8V/cell) for extended periods of time:

    Much like how over-charging LiPo batteries beyond their full charge level increases the internal strain on the pack, the same is true to a lesser extent for lower cell voltages over a long period of time. It's generally accepted that storing LiPo batteries at ~1/2 capacity, which translates to ~3.7-3.8V/cell, is safe and is a happy medium for minimizing battery degradation over a long period. If you plan on not flying your batteries for more than a few days, it's a good idea to run what's often called a "storage charge program" on your balance charger to charge/discharge your battery to ~3.7-3.8V/cell. Then recharge your batteries back to full as soon as is practical before flying.

  • Draining a pack too far:

    For normal use, permanent damage is caused to the battery if any of the cells drop below 3.0V/cell. Although as I mentioned previously, multirotors demand a lot from our batteries, so it's important that we try to keep the average cell voltage above ~3.4-3.6V during flight. This is because LiPo battery cell voltages drop off quite quickly below ~3.6V/cell, and so it's important to keep some margin to prevent any of the cell voltages from momentarily dipping below 3.0V before we can get the chance to land safely.

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  • $\begingroup$ This is all amazing info and I will certainly use it on my next battery, but I have heard that batteries can last up to 3 years. I haven't done any throttle punched and the most I every drain my battery is untill 10V. So I don't know what happened. Coud it be because my charger only charges from the balance lead and not the power lead as well? $\endgroup$ – DragonflyRobotics Aug 13 at 13:44
  • $\begingroup$ Well, the most accurate measure of battery wear is really a combination of "abuse" and charge/drain cycles, not in units of years, which is to say that there are ways to make a battery last a long time (e.g. in electric cars), but multirotors don't really have the right requirements for that to happen because of weight and complexity concerns. $\endgroup$ – ifconfig Aug 13 at 18:09
  • $\begingroup$ Ending at 10V on a 3s battery means you ended at ~3.3V/cell which is fairly close to the veritable redline. $\endgroup$ – ifconfig Aug 13 at 18:10
  • $\begingroup$ "Coud it be because my charger only charges from the balance lead and not the power lead" — No, that's fine. Nothing wrong with that. $\endgroup$ – ifconfig Aug 13 at 18:11
  • $\begingroup$ By the way, @DragonflyRobotics, If you're satisfied with my answer please accept it. :) $\endgroup$ – ifconfig Aug 13 at 18:13

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