Handling LiPos - Project-Stinger/Main GitHub Wiki

[!CAUTION] This is a NON-EXHAUSTIVE list of things to watch out for when dealing with LiPos. Treating LiPo-Batteries poorly can always lead to a fire.

Non-exhaustive safety info

  • Do not overcharge: Typical LiPos, such as the one that comes with Stinger V1, should be charged up to 4.2V per cell.
  • Use balanced charging only. If one cell has 4.15V, this does not mean that another one can have 4.25V. The maximum is for each cell individually.
  • Do not overdischarge: Typical LiPos, such as the one that comes with Stinger V1, can be discharged as low as 3.0V per cell. Since there is unpredictable voltage sag and very little capacity left below 3.6V, it is recommended to stop using a battery that is discharged below that and charge it up. If a battery reaches less than 3.0V on a cell, even for a short time, the battery has a high chance of catching fire on the next charging process.
  • Do not overstress: LiPos should be charged at 1C for maximum longevity, and typically up to 5C is allowed. Consult the battery notes. 1C = 1 capacity per hour, e.g. 1C on a 700mAh battery is 700mA of charging/discharging current. The maximum discharge rate is printed on the battery, e.g. 120C. For Stinger V1, a minimum burst current of 60A and a minimum continuous current of 30A are required.
  • Do not expose to extreme temperatures or direct sunlight
  • If a cell loses energy without being used, dispose of the battery. (This is only one possible sign that a battery is damaged)
  • When throwing a battery away, consult local facilities and regulations. Always discharge the battery to 0V before disposing of it.
  • Do not charge damaged batteries.

Good practices

  • LiPos should be stored at typically 3.8V per cell when they are not used for a prolonged amount of time (e.g. 1 week). Stinger V1 has a special mode for storage discharging. Both an empty and a full battery will lead to faster degradation.
  • If possible, take note of the internal resistance of the cells after the first few cycles. A significant increase in internal resistance of the cells is a solid indicator of bad battery health. Higher = worse. Typically, new batteries are <5mOhm per cell when fully charged. Fully charged batteries typically have lower resistances than empty ones. The internal resistance of a cell at 3.7V should never exceed 30mOhm.