Charge to 4.1v/cell
06-15-2013, 04:16 PM
#51
Join Date: Dec 2006
Location: ToowoombaQLD, AUSTRALIA
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RE: Charge to 4.1v/cell
Just an interesting side note, when looking for info about repacking my 14MZ battery someone posted a "how to" using a Fromeco Relion pack which happened to contain ICR18650-30A Lithium ion cells. Turns out those Li-ion cells can take (and need it to get rated capacity) 4.35v/cell and not the traditional 4.2v/cell that 18650 Li-ion cells are charged to.
06-19-2020, 06:27 PM
#52
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Extending Battery Life
Those plots all seem to show the voltage drops to 4.1v or below as soon as the real flight begins. The airplane is armed, sits around for a few seconds, has a takeoff burst, and by the time the sequence has started the voltage is well below 4.2v and likely below 4.1v.
You can also see that those with healthier packs never dropped below ~3.8v whereas the tired packs got down to 3.4-3.6V.
And that's kind of the point of this thread - 4.2v to 4.1v is not very noticeable in the air, happens almost immediately. Tired packs also happen, and would happen less often with less 'abuse' to the pack. 4.2v/cell is a harsh environment for the chemistry inside the battery, according to the technical articles.
You can also see that those with healthier packs never dropped below ~3.8v whereas the tired packs got down to 3.4-3.6V.
And that's kind of the point of this thread - 4.2v to 4.1v is not very noticeable in the air, happens almost immediately. Tired packs also happen, and would happen less often with less 'abuse' to the pack. 4.2v/cell is a harsh environment for the chemistry inside the battery, according to the technical articles.
06-21-2020, 11:30 AM
#53
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Personally, I am super cheap, and getting more flights from my lipo batteries at the expense of some flight time or performance is desirable. I just purchased some Charsoon Antimatter chargers (icharger 106B+ knockoffs) because they allow me to easily set termination voltage. Currently, I am charging to 4.1 volts/cell, but I am considering going to 4 volts/cell. (cheap!)
1. storage. ideally a fully charged (4.2 or 4.1) LiPo should never be allowed to stay at full charge for more than a few hours or more. If you aren't flying, the battery should be discharged to a storage voltage (3.80 - 3.85V) and left there until it's time to charge and fly
2. temperature. store batteries in a cool (50deg) environment when at storage charge and not being flown/charged. A small cube refrigerator is perfect for this. Also, never allow a LiPo to exceed 120degF during charging or storage or transport.
3. termination voltage. The life of a LiPo is influenced by the above 2, plus the "depth of discharge". In other words, charging to 4.1 and discharging/flying to 3.3 is not ideal...charging to 4.1 and stopping/landing at 3.7 is much better for longevity
4. charge/discharge current. if possible always charge at 1C (or less) and never try and exceed 50% of the pack's C rating. Failure to do so will increase the pack IR which will lead to higher internal temperatures which will mean loss of pack life.
If you follow these guidelines you can keep a LiPo running for many years of F3A flying .. albeit at shorter flight times as you mentioned.
