LiPo Battery Basics

THANKS FOR THE ARTICLE

Noticed/observed several examples of LiPo maintenance misinformation. With proper care, designed life of LiPo battery packs is for 400-plus charge/discharge cycles! 2009, I attended the 1-hour ThunderPower LiPo-care clinic at AMA EXPO. The three most helpful tips I took with me were: 1. A full function charger is well worth the money. 2. Evidence suggests stopping charging at 90%-95%, 4.10-4.15 volts/cell can increase battery cycle life, compared to 100%, 4.2 volt charges. Set TCS ACTION to STOP at 90%. 3. Do not store LiPo packs at "flight" charge. Use STORE charge spec of 50-60%, 3.85-3.90 volts/cell. LiPos do not like to be stored at a higher or lower voltage. Use STORE cycle if the pack is not used same day. And the obvious, do not discharge to below 3.0 volts/cell under load. Program ESC to cut-off 3.3 volts/cell. Better yet, time your flights considering the 90% charge baseline. I do that every flight  and have packs that still perform after 8 years. Proper care means better performance and practical $$ savings too!:-) Enjoy the confidence of flying healthy LiPo packs  Conclusion and documentation: Understood; Care of LiPo batteries has not been common knowledge. Anytime a LiPo battery swells it has somehow been misused/abused. But worse, can be dangerous! Good news is, none of you have to take my word for it. NEW packs from manufacture, measure 3.85 volts/cell, 60%. Check one yourself. Hyperion charger EOS0615i manual, http://media.hyperion.hk/dn/eos/EOS0615iDUO3-MAN-EN31.pdf page 5 excerpts: “TCS Feature (Terminal Capacity Selection % for Lithium battery types) TCS has two settings: TCS CAPACITY %, and TCS END ACTION.” “There are three good reasons why you might want to charge a Lithium Battery to something less than full capacity: * The first is for long-term storage. Lithium batteries are best stored after charging to 50%~60% of nominal capacity. However, rather than using TCS for this goal, it is easier and better to always use the STORE MODE function. STORE MODE automatically charges or discharges as needed to reach 60% TCS, then stops. * The second aim is to get more flight time in during a typical day at the field, by stopping the charge when the battery is 90% to 95% full, for example. Due to the CC/CV method by which LiPo are charged, charging the last few mAh back into the pack takes a LOT more time than the first few mAh did... So if you want to get in the air ASAP, and don’t mind a shorter flight then set TCS at 90%~95% could save you a good bit of charge time.” * “The third possibility is that evidence suggests that charging to 90%~95% can increase battery cycle life, compared to 100% charges. So in this case set TCS ACTION to STOP.” I time flights according to 90% charged, every flight :-) Then if you have followed all of this, you are skeptical of using LiPos for transmitter power. Can you imagine anyone adjusting transmitter LiPos to a STORE charge between uses? Some of you are too familiar with challenges of leaving power switch-ON as it is. My personal preference is NiMH for TX power. Mainly because NiMH batteries don’t need cycling. Fun Stuff! John Gluth