If your Drone lands with a low voltage warning even though the battery still shows power left in the battery then your battery may need calibrated.
"Charge and discharge the battery completely once every 20 charge/discharge cycles. Discharge battery until there is 8% remaining power or until it can no longer be turned on, then recharge it to the maximum capacity. This power cycling procedure will optimize battery life."
Fly your drone near the ground where it took off from until it auto lands and once it has landed leave it powered on until the battery turns its self off. Then fully charge the battery.
Buy a battery discharger on ebay and leave it on until the battery turns its self off. Then fully recharge the battery.