Taranis Q X7 Calculate Battery Run Time

Basic Calculation

• Wh = Watts x time in hours
• h = Wh ÷ W
• Wh - Watt-hour, a unit of capacity
• h - hours
• W - Watt
• W = V x A
• V - Voltage
• A - Ampere
• mA - miliampere, 1000 mA = 1A

Battery Options

• Battery Clip 6 x AA
  • 7.2 V NiMH 2400 mAh
• Battery Pack
  • 7.2 V NiMH 800 mAh
• Operating Voltage Range
  • 6 to 15 V
  • 2S, 3S Lipos are acceptable
• Maximum Battery Dimensions
  • 93.4 x 57.9 x 16.1 mm (battery clip with batteries measured using vernier calipers)
  • Very tight fit, go a couple of mm smaller in each dimension

Run Time

• Power Used ↑     Time ↓
  • Watts (W) = V x A
  • Tx, LCD, Modules
• Battery Capacity ↑     Time ↑
  • Watt Hours (Wh) = W x Time(h) = V x A x h= V x Ah (printed on batteries)

Tested Battery Capacities

• Battery Pack
  • 7.2 V x 0.8 Ah = 5.76 Wh
• Battery Clip
  • 7.2 V x 2.4 Ah = 17.28 Wh
  • Run time 3 x Battery Pack?
• Lipo 3S
  • 11.1 V x 0.85 mAh = 9.44 Wh
  • Run time 1.6 x Battery Pack?

Run Time Tests

Method

• LCD backlight brightness 100%, always on
• SD Card logs on
• No external module used or music playing
• Left on till drained
  • 6 V for NiMH & 9.4 V for 3S LiPo

Results

Discharge Curves

Run Times

• 800 mAh NiMH battery pack (5.76 Wh)
  • 4 hours 5 minutes
• 850 mAh 3S Lipo (9.44 Wh)
  • 7 hours 15 minutes
  • 1.8 x battery pack time (predicted 1.6)
• 2400 mAh NiMH batteries in the battery clip (17.28 Wh)
  • 13 hours 5 minutes
  • 3.2 x battery pack time (predicted 3)

Battery Capacity vs. Time Graph

The battery capacity vs. time graph enables us to determine the power consumed by the transmitter which is 1.3 Watts.

Calculation - Battery Capacity Required For A Desired Run Time

• If you want 10 hours
• Capacity Required = 1.3 Watts x run time hours required
  • 1.3 W x 10 h = 13 Wh
• NiMH 7.2 V
  • 13 Wh / 7.2 V = 1.8 Ah = 1800mAh

Reference - Battery Capacity Required Per Hour of Run Time

• 1 hours requires 1.3 Wh
  • NiMH 7.2 V - 180 mAh per hour
  • 2S LiPo 7.4 V - 176 mAh (180 mAh) per hour
  • 3S LiPo 11.1 V - 117 mAh (120 mAh) per hour

Calculation - Run Time Estimated Based On Battery Capacity

• If you have 1000 mAh NiMH
  • Capacity = 7.2 V x 1 Ah = 7.2 Wh
• Run Time Estimated = Capacity / 1.3 W
  • 7.2 Wh/1.3 W = 5.5 h

Reference - Run Time Estimated Per Wh or Per 1000 mAh

• 1.3 Wh of capacity provides 1 hour of run time
• 1 Wh of capacity provides 0.76 of an hour of run time
• 1000 mAh provides different hours of run time based on voltage
  • NiMH 7.2 V - 5.5 hours per 1000 mAh
  • 2S LiPo 7.4 V - 5.6 hours per 1000 mAh
  • 3S LiPo 11.1 V - 8.4 hours per 1000 mAh

Formulas For The Taranis Q X7

Battery Capacity

• Wh = 1.3 W x h

Run Time

• h =  Wh ÷1.3 W