Battery Storage

[mrmund]

So I need some info from the more experienced pilots here.
I flew 12 4s packs today. I probably won't fly more than 2 or 3 this week or maybe not at all. If the weather is good this weekend I might get a dozen or more flights. If the weather is crap(it's definitely winter here in the northeast now) it might be two or three weeks before I use them.
Should I charge most of them into "storage" and then charge them Friday night if I'm going to fly?
Charge them up fully?
What's the best procedure?
I've spent some $ on batteries and would like to maintain them and not waste charges or ruin them by treating them carelessly. I have an Imax B6AC v2 and the storage setting brings them to 15.28V or about 3.8 per cell. It's not a big deal to put them in "storage mode" but I'm not sure if it's better to charge them up fully after I fly when it might be a week before I use them or it could be weeks.
What's the best way to handle this so they last the longest?
Thanks

 

[HighTechPauper]

I keep all of mine at about 3.9v per cell, that is about 60% charged so they are not degrading, and they charge pretty quickly when needed. I have left batteries charged for over a month and found they still fly fine when I go to fly them. I try not to leave them charged fully for more than a few days so I will often drop them to just under 4v so they are safe to top up quickly before flying. IMHO

 

[droneguy]

So I need some info from the more experienced pilots here.
I flew 12 4s packs today. I probably won't fly more than 2 or 3 this week or maybe not at all. If the weather is good this weekend I might get a dozen or more flights. If the weather is crap(it's definitely winter here in the northeast now) it might be two or three weeks before I use them.
Should I charge most of them into "storage" and then charge them Friday night if I'm going to fly?
Charge them up fully?
What's the best procedure?
I've spent some $ on batteries and would like to maintain them and not waste charges or ruin them by treating them carelessly. I have an Imax B6AC v2 and the storage setting brings them to 15.28V or about 3.8 per cell. It's not a big deal to put them in "storage mode" but I'm not sure if it's better to charge them up fully after I fly when it might be a week before I use them or it could be weeks.
What's the best way to handle this so they last the longest?
Thanks

Maybe you already have gotten your answers on this, but I thought I'd add some additional information on battery management. You should always keep any LiPO battery at storage voltage until you are ready to go out and fly. Charging the morning of is best but charging the day before is typically ok. The risks to the health of the batteries occur if they drop below 3v or stay fully charged for without discharging withing 24-48 hours after a full charge. If the battery ever does drop below 3v, there is no need to immediately panic. The chemistry will survive many trips below 3v and often exhibit no major issue IF... and this is a big IF they don't stay below 3v for too long. Leave them below 3v for a week and the chemistry will likely be permanently damaged. But if you charge them back up from below 3v at a very low current (100mA max), you can often save them from death and despair. Charging a sub 3v LiPO at a high current is VERY DANGEROUS and should never be attempted unless you want a firey bomb on your hands. It also goes without saying, that you should never charge LiPOs unattended. not even for 5 minutes while you run out real quick. Putting your LiPOs at a storage voltage 3.8v (most good chargers have this mode) will put the chemistry in the most stable state where the risks are minimal and the drain will be tiny. You can store them at this voltage for months or years. When you charge a LiPO to 4.2v the batteries have a lot of energy stored in them. If kept this way for long periods of time, the chemistry will start to change and you will also see voltage leakage (voltage drops quick then slowly) This is because the chemistry of a LiPO is designed for high current discharge but not for long term retention in this state. Keeping a LiPO at full charge is dangerous (due to the high energy potential) but also you will see the chemistry change and over time It will sag out much quicker. The other risk is that if you use a parallel charging board and any of your batteries have bad chemistry, they could affect the health of your other batteries. (impedance mismatch and high discharge rates during parallel balancing) There are many other important topics related to LiPOs but given the time, I'll end it there for today.

In summary, keep you LiPOs at storage charge when not using them and they will have a long happy life.