If you've ever found one of your LiPo batteries swollen or seriously deformed, perhaps from discharging at too high a rate or after a crash, you have a damaged LiPo battery. Damaged LiPo batteries can potentially cause fires, and it is important to handle, fully discharge, and dispose of damaged LiPo batteries responsibly.
Here is my method for carrying this out. It requires the following easily obtained items in conjunction with some solder, a soldering iron, and some patience.
2. Lightbulb holder (~$3 from Home Depot)
3. Male connector which matches with your battery's female connector (as a hobbyist, you probably have a few lying around somewhere)
4. Heat shrink
5. LiPo bag (should already have one)
Step 1: Use a LiPo Safe Bag
Using a LiPo safe bag is important. In case the damaged battery catches fire, the bag prevents more oxygen from feeding the fire, and helps to snuff the problem out. Always keep your LiPo batteries in a LiPo bag.
Step 2: Solder Your Male Connector to the Light Bulb Socket Wires
Solder the male connector to the light bulb socket wires. Generally, the black wire will be + and the white wire will be ground. You can check this by using a multimeter to verify continuity between the light bulb threads (ground) in the socket and the white wire (also ground).
Step 3: Insert Light Bulb, Connect to Battery
Now, insert the light bulb into the socket and connect your battery. The light bulb + socket will act as a resistor, in this case approximately 20 ohms. This allows the battery to slowly drain by dissipating energy in the resistor. I waited a day before moving to the next step, at which point I measured a small 0.3 V across the battery leads (while still connected to the light bulb + socket).
Step 4: Short the Battery Leads
Now that there is very little potential energy left in the battery, I cut off the connectors and soldered the main leads together. This discharges the battery fully, and ensures that the battery can no longer store electrical energy.
Step 5: Dispose of the Battery Properly
You have done your due diligence by draining your battery of electrical energy, and ensuring it cannot hold electrical energy. Now, you need to drop off the batteries at a location where people are prepared to dispose of rechargeable batteries. If your city has an E-Waste collector, that's a possible option.
In my case, I went to the local Home Depot, which is a listed drop-off location at https://www.call2recycle.org/locator Once I found the drop off location, I made sure to follow the listed instructions. I placed my battery in a supplied plastic bag, and placed it into the correct orange bin.
Once you have discharged and disposed of your battery responsibly, congratulate yourself for doing the right thing. Get a replacement battery, and continue to enjoy your hobbies!