Is it a good idea to recharge LIPO battery every time after use? How often should we do it?
A LiPo should not be discharged below 3.2V per cell.
It also has a slow self-discharge, so if you're not going to use it for many months, giving it a charge so you know it won't go below 3.2V is helpful.
Charging all the way to full (4.2V / cell and only a small current remaining) will wear the oxide in the cell, though, and thus "consume life" of the cell. Charging it up to a lower voltage will damage it less.
Thus, a good idea might be to charge to 3.9V or 4.0V per cell, use a trickle charge like 0.2C, and cut off the charging once it gets there. This will pad against self-loss, and also make sure that the battery is at least 70% or so ready to be used if you need it immediately, yet not wear it out too much. (This is what I generally do.)
Note that you'll need to use a charger that lets you set the voltage. Personally, I use a high quality benchtop power supply, and charge the full stack (without worrying about balance.) I set the current limit to something small, and then keep an eye on it, and when the battery draws less than the current limit, at the target voltage, I call it done.
Once I want to charge it full, I use a balance charger to make sure the cells are in "harmony," but you really don't need to do that every time you charge.
If you know that you will use the battery within a week or two, though, just charge it full right away.
If you want to know more Lipo battery knowledge, you can read this article:
