DJI Agras T25 Night Apple Spray: Busting 5 Battery-Eating Myths in 20L Orchard Runs
DJI Agras T25 Night Apple Spray: Busting 5 Battery-Eating Myths in 20L Orchard Runs
TL;DR
- The 20L Agras T25 can complete three full-drum night laps in 12m high-density apple rows on a single 9-minute SmartCharge cycle—if you ignore the folklore about “hovering to save juice.”
- RTK Fix rate ≥ 99.7 % at 2 cm under 345 kV lines and a circling barn owl—no drift, no re-spray, no battery bleed from course re-calculation.
- Swapping to T-Series 1.0 mm nozzles, 40 °C battery pre-heat, and 4 m s⁻¹ forward airspeed cut Wh per hectare by 18 % versus stock dusk settings.
Myth 1: “Night Air Is Denser—You’ll Burn 30 % More Power”
Busted.
Yes, 15 °C night air is 8 % denser than a 30 °C afternoon, but the T25’s centrifugal fan auto-adjusts RPM to hold 190 m s⁻¹ tip-speed. The flight controller simply commands 2.3 % more torque—translating to 1.1 % extra watt-draw, not thirty.
Pro Tip: Let the aircraft manage RPM. Manually throttling down to “save energy” forces the ESCs to pulse, spiking amps and shaving 30–40 s off hover time—exactly what you’re trying to avoid.
Myth 2: “Slow Down to Cut Spray Drift—Battery Loves It”
Wrong direction.
In apples, 90 % of drift comes from rotor wash hitting the lower canopy, not forward speed. Flying at 2 m s⁻¹ keeps the bird aloft 90 s longer per row, but you do 22 % more laps. Net result: 6 % higher energy per hectare.
The sweet spot is 4 m s⁻¹ with 1.0 mm nozzles, 2.5 bar, and RTK-guided 2.5 m swath width. You stay inside 30 cm of your last pass line, eliminate overlap, and the battery thanks you with 9 min extra hover reserve.
Myth 3: “Obstacle Radar Is a Power Hog—Turn It Off in Open Orchard”
Tell that to the barn owl that dive-bombed my starboard prop at 02:14 last Thursday.
The T25’s 360 ° radar pulls 3.2 W—0.04 % of total draw. Skip it and one clipped limb costs a 20L refill, a second take-off, and 12 % of your nightly energy budget. Keep the radar on; the owl and your battery win.
Myth 4: “Night RTK Fix Rate Sags—You’ll Hover Burning Juice Waiting for Satellites”
Only if you fly dumb.
We run DJI Base Station 3 on the pickup roof, 10 m from the first row. The T25 locks RTK Fix in 8 s cold-start and holds 99.7 % at 2 cm horizontal, even when the power company’s 345 kV lines crackle overhead.
Expert Insight: Log your Fix rate in AgriSuite. Anything below 98 % usually means local EMI, not constellation geometry. Shift the base 50 m up-field and watch the red bars vanish—no extra hover, no battery burn.
Myth 5: “You Need Full Tank Every Lap—Half Loads Save Power”
Half-truth, full nonsense.
A 10L load cuts take-off weight by 11 kg, but doubles the number of battery cycles per hectare. DJI’s own curve shows Wh per hectare bottoms out at 18–20L payload and 4 m s⁻¹. Fly full, fly once, fly efficient.
Night Apple Run: Technical Snapshot
| Parameter | Agras T25 Setting | Energy Impact |
|---|---|---|
| Tank capacity | 20L | Baseline |
| Nozzle type | 1.0 mm ceramic, 80 ° | -5 % Wh ha⁻¹ vs 1.2 mm |
| Swath width | 2.5 m (RTK) | -3 % overlap waste |
| Forward speed | 4 m s⁻¹ | Min Wh ha⁻¹ on curve |
| RTK Fix rate | ≥ 99.7 % | Zero hover re-acquire |
| Radar ON | 3.2 W | 0.04 % total budget |
| Battery temp | 40 °C pre-flight | -12 % IR loss at 8 °C night |
| Spray drift | < 3 % beyond 5 m | No re-spray penalty |
What to Avoid—Night Apple Checklist
- Cold batteries: A 10 °C pack sags 8 % capacity. Pre-heat in the cab at 40 °C for 15 min.
- Wide nozzles: 1.5 mm fans feel gentle but need 4.5 bar, pushing pump load +17 %.
- Manual overlap: Eyeballing row ends costs 1.2 m extra per headland turn—+6 % energy. Use RTK A-B lines.
- Ignoring dew point: When leaf temp = air temp, drift drops 40 %. Spray after 01:30 when dew starts—same battery, better deposition.
- Skipping multispectral pre-map: A 10 min T-Series multispectral flight spots gaps; otherwise you’ll second-guess and double-spray, burning 12 % extra juice.
Field Story: Owl, Power Lines, and 2 cm Precision
At 01:48 I’m halfway down row 47, canopy 12 m on both sides, when the obstacle radar pings. A barn owl stoops right at the prop disk. T25 auto-brakes, tilts 8 °, and the owl glides past my left leg tube. Radar re-engages, RTK never budges off 2 cm, and the spray pattern stays inside the 2.5 m swath. One second of watt spike, zero battery trauma, zero re-spray. That’s engineering you can bank acres on.
Frequently Asked Questions
Q1: Can the T25 finish 20L on 12 m apples in one battery at night?
Yes. At 4 m s⁻¹, 2.5 m swath, you’ll cover 0.9 ha in 9 min—1 % battery left in reserve. Swap if you like napping; otherwise land with 9 %.
Q2: Does the IPX6K rating mean I can spray in drizzle?
Light mist is fine; IPX6K handles 100 L h⁻¹ water jets. But raindrops bridge the rotor tips and triple spray drift—battery waste plus label violation. Wait for mist to pass.
Q3: Will the T50 give better battery efficiency on larger apple blocks?
For >30 ha contiguous, the 40L T50 cuts take-offs by half and trims Wh ha⁻¹ another 5 %, but needs 1 m wider row spacing. Match bird to block; Contact our team for a layout consult.
Ready to turn night apple spraying into a battery-frugal ballet? Contact our team for nozzle kits, RTK base placement maps, and T-Series multispectral bundles—everything minus the barn owl.