Remember to make sure it is smooth after melting together. These batteries do fit snuggly in the Quads. If there is any material sticking up, it may not go into your Phantom smoothly.
Plus, use the soldering iron sparingly. A little at a time, then let it cool, so you don't put any excess heat on the battery.
You need to also watch it carefully when charging and make sure it doesn't begin to swell. Of course any swelling you should dispose of the battery immediately.
If you are gonna use the soldering iron, I would do it outside and not in your house!
Please be careful.
All in All, these batteries are volatile time bombs and can do allot of damage. The cost $149, some places cheaper. I would just dispose of it! Not worth burning your house or apartment down.
Take Care.
JT