Had my ST-16 Fully charged. Flew 2 batteries 1 down to first battery low warning, the other only about 10 minutes. Brought everything home, charged up the first battery, went out to take some sunset video. Flew around a bit and had the H hovering at about 25 feet right above me, and the battery in the ST-16 dies. NO WARNING WHAT SO EVER just like you had removed the battery. The H just sits there, blinking away in angle mode, no control input what so ever. I was hoping RTH would kick in and it would auto land, but NO. It does change the tail Light to RED (RTH) after time. The H just hovers away while panic sets in. Quick run in the house grab the car keys, plug the ST-16 into the USB charger in my car. After an eternity it turns back on (H is still @25' ) I get control reestablished and land the H. I was so lucky. Yuneec will be getting a phone call from me tomorrow. 1) Why NO low battery warning from the ST-16 battery? (display showed 1 bar down from full) 2) Why did the RTH function not kick in? The tail light did turn to RED. 3) When plugging the ST-16 into the Yuneec charger why does it show the battery still at 50% ? I am not sure when the H went from Angle to RTH (according to the tail light) but it never did land. It never flew up to the 33' mark, or make any other attempt to change position. The H was less that 20 feet from my take off position. I hope this is a one off problem, but until I receive some answers, keep an eye on your ST-16 battery. I could have been 400' up and 1000' down range when this happened.