If you have an old or damaged LiPo battery that needs to be disposed of, it's imperative that the battery be fully discharged before the battery is disposed of. Throwing the battery away without discharging the battery can result in fire (especially if the battery is punctured or crushed), and since trash cans have ample combustible materials, a very hazardous fire can result if the battery were to ignite.
For any old, damaged or faulty battery that needs to be safely disposed of, the safest option is a battery recycling center. However, in the case of a damaged battery that is not safe for transport, we suggest a salt water bath to deplete the battery of voltage.
Submerge the LiPo battery in a salt water bath that contains 1/2 cup of salt per gallon of water and mix thoroughly, making sure the full battery is submerged. You will see bubbles forming from the negative power leads (and balance lead) that indicates the discharge is taking place. Depending upon the level of charge, the battery can take up to (2) weeks to fully discharge via this method. However, since the battery is fully submerged in water, this is a safe way to deplete the battery of voltage.
After (2) weeks of salt water submersion, test the battery with a volt meter to verify the battery as depleted. If the battery reads 0.00V, the battery can be safely disposed of.