Tornado 920 Plus
Zippy Dual 5000mA Flight Test
Having charged the Zippy 5000mA batteries to full capacity at a 1C charge rate it was time to put them to use for flight testing. The following are conditions and observations made before, during, and after the flight. For those lacking patience the end result was a flight flown normally, camera recording 4k from the time of takeoff, gear cycled multiple times, with climbs and descents, for a
total time of 0:25:39, or 38 seconds more than the best I have obtained using three new Yuneec batteries. Considering I paid ~$118.00 for a pair of Zippy batteries and obtained slightly better flight time than when using three new Yuneec batteries, and that Yuneec’s price for a package pair works out to $139.995 each, for a total cost for three batteries equaling $419.985, my use of Yuneec batteries for the 920 has reached an early end. I can buy three sets of Zippy batteries for $66.00 less than a set of three Yuneec batteries. Topping that is a pair of Zippy batteries weighs less than three Yuneec batteries which means the system does not have to work as hard.
The 2000mA of additional capacity using the Zippy 5000’s over the Turnigy 8000mA Graphene battery provided ~4 additional minutes of flight time in conditions roughly 10 degrees colder than when the graphene test was performed. The wind conditions for the Zippy test were easily double those for the graphene test. We might interpolate that each 1000mA of additional capacity could add 2 minutes of flight time when using batteries of higher quality that what Yuneec provides. What is certain is that a pair of Zippy 5000mA batteries provide flight time at least equal to what three Yuneec batteries provides for the 920 Plus. We have alternative battery choices available to us, we just need to research and take advantage of them.
For those that like statistics, the following;
Conditions:
- Baro: 29.88inHg
- OAT: 54.6*F
- Wind: 3-7MPH
- Density Altitude: negative 105’ MSL
- Humidity- 55.8%
- Dew Point: 33.4*F
- Sky: Overcast, incoming storm front
- Altitude of flight: varied, 78’ to 392’AGL
Battery State:
Zippy #1 charged to 25.2v as indicated by Hitec X2/400 dual DC Charger. Independent volt meter check indicated 25.22v
- Cell Charged Voltages: 4.202, 4.198, 4.202, 4.212, 4.202, 4.212
- Pack Internal Resistance-Charged: 2,2,3,3,2,2 =14 mOhms
- Pack Voltage, Post Flight: 21.88v
- Discharged Cell Voltages: 3.625, 3.655, 3.630, 3.649, 3.649, 3.672
- Discharged Internal Resistance, Battery Warm: 2,1,2,1,2,2 = 10 mOhms
Zippy #2 charged to 25.2v as indicated Hitec X2/400 dual DC Charger. Independent volt meter check indicated 25.21v
- Cell Charged Voltages: 4.202, 4.203, 4.197, 4.202, 4.202, 4.107
- Pack Internal Resistance-Charged: 3,2,2,3,2,3 = 15 mOhms
- Pack Voltage, Post Flight: 21.88v
- Discharged Cell Voltages: 3.625, 3.655, 3.649, 3.644, 3.659, 3.654
- Discharged Internal Resistance, Battery Warm: 2,1,1,1,2,2 = 9 mOhms
Voltage after power up: 25.1v
Voltage at Takeoff: 24.9v
First Voltage Warning @ 21.8v, Time 0:17:20
Observation: Voltage remained at 21.8v for much longer than usually experienced. The voltage warning did not occur until the voltage had achieved and maintained 21.8v for a considerable period of time. Unfortunately, I did not note and record that period of time. Voltage did not fall below 21.8v until 0:21:05
Second Voltage Warning @ 21.6v, Time 0:22.45
Observation: ST-16 initiates a repeated and continuous vibration cycle that is maintained until power is shut down.
Landing Voltage: 21.3v, landed manually
Post Flight Battery Temperatures: Warm, not hot. Measured using subjective method of holding battery to my cheek.