Help! LiPo voltages at different stages ?

[Snoopy1]

OK have question on LiPo. Yes we all know max voltage is 4.20 volts, storage is 3.85 volts and minimum is 3.2 volts for me.
Ok 3.85 volts is for storage. But what voltage is acceptable to leave a LiPo at for say 5 days and NOT do any damage. Or do you need to always bring it down to 3.85 volts .
Some times I will only get time to do one flight on my second plane that I bring to the field and will still have say 4.1 volts left would you leave the pack at that voltage for 5 days and just bring back it to full charge the days you go flying again.

 

[acerc]

I don't discharge mine between in season flights but my season is all year long. I also do not charge at a high rate, typically 1 amp, and I also replace them annually. Hmmm, maybe I am not best suited for responding to your question. My understanding is that Li-Po has a "number of cycles" life and any charge no matter how small is a cycle. So if there is enough juice for a flight or two the next time out I'll burn those flights before recharging.

 

[Snoopy1]

That is an interesting thought. And yes I have read it several times they have a number of cycles and then it is over. But I thought that was from full to empty.
Same as you always charge at 1c or less most times my charge is set at 1 to 2 amps.

 

[acerc]

The little Tundra hardly ever gets both batteries depleted on the same day, occasionally not even the same week.

 

[Snoopy1]

The little Tundra hardly ever gets both batteries depleted on the same day, occasionally not even the same week.

Thanks for input it is always nice to know how others are doing things successfully.

 

[pawnshopmike]

Sometimes I charge at 12c. Almost always charge at least 5c. Most of my batteries are several years old and some of them have over 200 cycles. Only thing I’ve found that kills them is storing long term at full charge.

 

[Snoopy1]

I agree at full voltage does ruin them quickly. But does storing them at 4.1 volts, does that damage the battery or not . That is what we are trying to figure out or is there a curve to the deterioration.

 

[MarkF]

From the moment lipos are made they start to deteriorate. The higher the voltage the worst it gets. Now leaving them at full charge for a week or so is fine. What can be worst is leaving them under 3.7 volts. If your cells sit at a low SOC they can begin to puff. Remember 80% is 3.75 per cell. Discharging to less than that is damage to your cells and 3.2 is a death sentence. After you land, your resting voltage is what matters and not your cut off, but if your under 3.7 then your pre maturely killing your pack and that is what make packs have short cycle life. 4.1 is not as bad as low voltage but ok if for just a short while.

 

[John Vesper]

That is an interesting thought. And yes I have read it several times they have a number of cycles and then it is over. But I thought that was from full to empty.

If you completely "empty" it you will destroy the battery in no time.

To further confuse things, the "capacity" (mah) rating is usually excessive. I fly a fairly high performance plane and get about 5-6 minutes of throttle time (excluding "idle" throttle settings, on the down lines), which brings me down to about 3.6 to 3.8 volts per cell. When I charge them back up, It usually takes about 28-2900 mah of energy, for a cell with a 5000 mah rating. I've never done it (but may with an old cell that I'm about to toss,) but I strongly suspect that getting the full 5000 mah out of it would take it down below the 3.2 volt level, which is territory into which you do not wish to explore.

 

[Jetpainter]

Remember 80% is 3.75 per cell.

Is this a typo? From everything I've read, 80% is like 4.06 volts and 3.75 volts would be about 40% just wondering.