If you have no other way, fill a couple of old pairs of socks with sand or other heavy material. Lay one on each of the landing gear legs, for a total of 4 socks. 4 or 5 lbs of weight will do. In a clear space that will remain clear, power up the H, props on, and the ST-16. Arm the motors and let them run at idle, no more than idle, while watching the battery voltage on the ST-16. Stop when the battery voltage with the motors spinning reaches 15v. It will rise to ~15.3v when the motors are stopped.
The ST-16 can be stored fully charged as it has a different kind of battery.
Sent from my iPhone using Tapatalk