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You can build a multirotor that receives continuous power from the ground, but it is not a standard quadcopter with a longer battery lead. A practical system needs a carefully sized power tether, airborne power conversion, mechanical load management, a tested backup-power and landing plan, and compliance with the rules for the operation. For most designs, the sound starting architecture is a regulated ground supply feeding a higher-voltage, lower-current tether, an airborne DC/DC converter, and an onboard battery or buffer that can keep the aircraft flying long enough to respond to a fault.
What a tethered-power drone is
A tethered-power drone receives electrical energy from a ground station through a cable while airborne. The cable is also a physical load: it has weight, drag, stiffness and tension, and it can snag, swing or pull the aircraft off position. The ground station must be secured, and the aircraft must remain controllable if the supply or cable fails.
Keep these terms distinct when choosing a design:
- Power tether: Conductors carry electrical power from the ground to the aircraft.
- Data tether: Ethernet, fiber or another link carries communications. It may be combined with a power tether, but a data tether alone does not extend flight time.
- Mechanical tether: Primarily restrains or retrieves the aircraft; it may or may not carry power or data.
- Hybrid tether: Combines power, data and/or a mechanical load path in one cable or assembly.
- Captive drone: An aircraft intentionally constrained by a tether and ground installation.
- Drone-in-a-box: An automated dock that can charge or swap batteries between flights. It does not necessarily power a drone while it is airborne.
“Continuous flight” is conditional: endurance depends on the ground supply, weather, cable and station limits, maintenance, payload, airspace and operator. A tether limits travel but does not make the aircraft immune to flyaway, snag, power or regulatory risks.
Decide whether tethering fits the mission
A tether makes sense when the aircraft needs to hold a defined area for a long period, such as for observation, lighting or communications, and a clear route can be maintained between aircraft and ground station. It is a poor match for missions that require unrestricted horizontal movement, frequent repositioning, or a cable routed across roads, waterways, runways or public access.
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- Continuous power for extended drone operations Provides stable and reliable power for DJI Matrice 400 drone missions, supporting long-duration aerial deployment without frequent battery changes.
- High-performance tethered power system Converts AC power into high-voltage DC power with 800V output and 4kW rated power, delivering efficient and stable energy transmission for professional UAV operations.
- 110m tether cable with portable ground station Includes a 110m tether cable and lightweight ground station design, enabling flexible deployment for emergency response, security, and industrial applications.
- Reliable communication and safety protection Features intelligent fault alerts, automatic power-off protection, grounding support, and HDMI and Ethernet video output for dependable field operations.
- Expandable solution for professional applications Supports multiple drone payloads and up to 1500W lighting output, making it suitable for public safety, emergency response, surveillance, and other continuous-operation scenarios.
| Option | Best suited to | Main trade-off |
|---|---|---|
| Tethered multirotor | Persistent observation or relay over a controlled site | Long endurance in a limited area, at the cost of cable, station, wind and snag constraints |
| Battery multirotor with swaps or rotation | Mobile missions and sites without a safe tether route | Requires battery changes, charging or multiple aircraft rather than a live power cable |
| Tethered balloon | Long-duration stationary observation where wind and payload allow | Different lift, deployment and weather constraints; not a maneuverable multirotor |
| Mast or observation tower | A fixed camera, light or antenna position | Can avoid aircraft operation altogether, but cannot be repositioned in flight |
| Drone dock | Automated repeat flights with charging or battery service between sorties | Reduces turnaround work but does not, by itself, provide airborne power |
If the cable cannot be kept clear, the ground station cannot be anchored or supervised, wind routinely exceeds the aircraft’s tested limits, or there is no safe landing area, choose another platform.
Choose the power architecture
For most serious prototypes, transmit at a voltage higher than the aircraft’s propulsion bus, convert it near the aircraft, and retain onboard energy for failover. The conversion and battery path must be designed as a system; do not improvise a parallel connection between a supply and flight battery.
Low-voltage tether
A low-voltage cable carries a voltage close to the aircraft’s battery bus. Its simple voltage relationship can help with a short, low-power bench or flight prototype. But for a given power, lower voltage means higher current. That drives up cable loss, voltage drop, conductor size, connector stress and heating, so this approach scales poorly with distance or aircraft power.
Higher-voltage tether with airborne conversion
A regulated ground DC supply sends higher-voltage, lower-current power through the cable. An airborne DC/DC converter then produces the voltage required by the flight-power system. This can make a longer run more practical, but the converter adds mass and heat and must tolerate input variation, motor-load transients, vibration and electromagnetic noise. Higher voltage also raises shock and arcing hazards; choose the voltage only after considering the cable, converter, insulation, connectors, site and operator protection.
Add a managed battery buffer
A buffer can supply short transients, bridge a supply interruption and give the aircraft time to land after a fault. A more substantial emergency battery must be sized for a defined response, not assumed to guarantee a safe landing. The power path needs a deliberate switchover strategy, charging control, current limiting and reverse-current protection. A capacitor can bridge very brief transients, but it is not a substitute for descent energy unless its usable energy and the aircraft’s actual power demand demonstrate that it is sufficient.
DJI documents this kind of integration in its Matrice 400 tethered ecosystem: its tethered battery is used as backup or buffer, the ground supply has specified operating conditions, and the aircraft responds to an unstable tether supply by switching to the battery; it forces a landing when that reserve is depleted. Those behaviors and requirements are specific to that system, not a general DIY recipe. DJI Matrice 400 tethered-system documentation
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- Come with 1 pcs XT60 power supply cable
Estimate power and cable losses
There is no universal wattage for a tethered drone. Required power changes with all-up mass, propellers, motor and ESC efficiency, aircraft geometry, payload, wind, altitude, climb rate and the extra drag from the tether. Measure the aircraft on its normal battery before designing the supply: record hover power and peak demand during climb and maneuvering, then account for conversion losses and operating margin.
Use these first-order relationships:
- Current:
I = P / V, where P is transmitted power and V is tether voltage. - Resistive loss:
P_loss = I²R. - Voltage drop:
V_drop = IR. - Ground power estimate:
P_ground ≈ P_hover × safety factor ÷ (tether efficiency × converter efficiency).
For illustration, an aircraft drawing 800 W in hover does not mean an 800 W ground supply is sufficient: climb, gust response, tether loss and converter loss all require additional capacity. Establish the margin by measurement and testing; no single safety factor applies to every airframe or mission. At fixed power, doubling transmission voltage approximately halves current; for the same cable resistance, that reduces resistive loss to roughly one quarter.
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Select the tether, converter and protection
Specify the cable for electrical and mechanical service
Compare cable options by conductor resistance per unit length, full round-trip length, continuous and peak current ratings, insulation voltage, temperature and UV ratings, abrasion resistance, flexibility, bend radius, weight per meter, water exposure, connector compatibility and mechanical breaking strength. If the aircraft needs a data path, specify the Ethernet or fiber arrangement as well.
Decide explicitly how tension is carried. Options include a cable with an integrated strength member or a separate load-bearing line. Add suitable strain relief, a managed reel where appropriate, a swivel if the arrangement requires one, a ground anchor and a deliberately engineered breakaway or weak link if the hazard analysis calls for it. Do not hang the cable from an unreinforced battery lead or flight-controller connection, or rely on electrical conductors alone as an unanalysed structural attachment. The FAA public-safety checklist describes a taut, appropriately load-rated tether attached to a ground station and calls for safe behavior after power or flight-control failure. FAA checklist for actively tethered public-safety UAS
Design the airborne power path
At minimum, evaluate input overcurrent protection, reverse-polarity protection, surge suppression, filtering, inrush limiting or soft start, DC/DC conversion, regulated output, thermal monitoring, voltage and current telemetry, undervoltage and overvoltage behavior, enclosure and cooling, and the battery-management and switchover circuit. Isolation may be necessary depending on the supply, converter and installation. Use components rated for the actual voltage, current, transients, vibration and environment; a generic converter’s nominal rating alone does not establish suitability.
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- 【Wide Compatibility】Compatible with a wide range of DJI drones including DJI Mini, Air, Mavic, Phantom, Spark, FPV Series. You can connect it with their Battery Charger/Charging Hub.
- 【Universal Fit】With an overall length of 1M, this AC Power Cord offers flexibility and convenience in various charging setups, making it an essential accessory for DJI drone enthusiasts.
- 【Safety Guaranteed】Our AC power cord has undergone rigorous safety testing to safeguard both you and your connected devices, offering peace of mind during drone charging sessions.
- 【Product Specification】The plug features a 6A 250V rating, while the flat cable is rated at 300V/300V with a 2x0.75mm2 wire gauge, providing a safe and reliable power supply.
- 【Material & Package】Made of high-quality materials, it is not easy to break or crack, ensuring stable output of current. You will get AC Cable (NA) *1.
ArduPilot’s documented home-made tether prototype illustrates the kinds of issues involved: it uses a ground supply, a high-current power cable, remote voltage-sense wires, a large capacitor and a transient-voltage suppressor at the aircraft end. These component choices and values are specific to that example and should not be copied into another system without engineering analysis. ArduPilot warns that its design involves high-power electronics capable of causing serious injury or death. ArduPilot home-made power tether
As a scale reference only, DJI specifies its Matrice 400 tethered battery around a 50 V input, with an average power rating of 1,800 W and an instantaneous peak rating of 3,500 W. These are specifications for that DJI ecosystem, not generic design targets. DJI Matrice 400 tethered-system documentation
Ground station and power source
Choose a regulated supply or generator that can sustain the measured load and transients, with source-side protection and a defined emergency stop. Protect any mains-derived equipment against outdoor moisture and physical damage, and have electrical installation reviewed by a qualified person. Do not lift a ground battery by its live power cable; DJI specifically warns that its tethered-battery connection cable is current-carrying and must not be used to lift the battery. DJI Matrice 400 FAQ
Define failure behavior before flight
Write down what the aircraft will do for each fault, how the operator will know it happened, and how the system will be tested. Flight-controller voltage sensing or ordinary battery failsafe behavior may not cover a tether converter or power-path fault. Check the firmware documentation for the exact installed version rather than assuming a parameter or response exists.
| Fault | Risk | Design and test response |
|---|---|---|
| Ground supply loss or tether separation | Loss of flight-bus power or abrupt transfer to reserve | Test automatic switchover, low-voltage detection, alarms and controlled landing using a deliberate test switch |
| Voltage drop under load | Converter reset or undervoltage during climb or gust response | Measure both ends under peak load; assess remote sensing, conductor size, transmission voltage, run length and buffer design |
| Converter failure or overheating | Sudden loss of regulated flight power | Monitor faults and temperature; verify reserve power and thermal behavior under representative load |
| Tether snag or sudden tension | Uncommanded roll, yaw, descent or structural overload | Keep a clear flight envelope, manage cable, monitor length or tension where possible, and define an abort or landing procedure |
| Reel or ground-station movement | Changing cable tension pulls the aircraft or alters its position | Anchor or ballast the station, align the cable path and set weather and operating limits |
| Connector failure | Intermittent power, arcing or separation | Use locking, voltage-rated connectors with strain relief; inspect contacts and never use the connector as a structural fitting |
| EMI or navigation disturbance | Compass, GPS, radio or controller errors | Separate high-current wiring from sensitive sensors, filter as appropriate, and check logs and navigation with the tether energized |
Include a buffer battery or emergency battery only with a defined role and verified usable energy. Test failure responses without damaging a live cable or exposing people: use a controlled electronic switch, current-limited setup or dummy load where appropriate.
Account for tether effects on flight
The tether can pull the aircraft sideways, act like a swinging pendulum, transfer ground-station movement, catch on structures, add yaw or roll disturbances, and increase propulsion demand through drag. A taut line can develop load quickly; a cable that seems harmless near the ground may behave differently as its length and wind exposure increase.
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Use a managed reel and maintain a clear path. Set a maximum cable length and operating height based on the site and system, establish wind limits through testing, and keep people clear of the station, line and aircraft’s landing area. Elistair advises leaving a safety margin inside its station to reduce unpredictable movement from gusts, an example of how cable management and wind affect commercial operation too. Elistair client support
Build and test in stages
- Define the mission. Record aircraft and payload mass, intended altitude and cable length, hover duration, wind limit, location, power source, data-link needs, safe landing area and acceptable development risk. Check that a cable route and station position are practical.
- Establish an aircraft baseline. First fly the untethered aircraft reliably on its normal battery. Measure hover and peak power, review logs, and confirm its independent emergency-flight capability. Do not use tethering to compensate for an unproven airframe.
- Choose a transmission voltage and cable. Match them to measured load, run length, converter availability, insulation and connector ratings, operator safety and site restrictions. Do not select a voltage from a rule of thumb without the full system design.
- Bench-test the power system. Use a dummy load before motors or propellers. Check regulation, startup and inrush, load transients, voltage drop, temperatures, connector heating, overcurrent protection, short-circuit behavior, supply loss and battery switchover.
- Verify installation and controls. With propellers removed where appropriate, confirm telemetry, shutdown, strain relief, connector retention, backup behavior and electromagnetic compatibility. Arrange a remote emergency stop and a controlled test area.
- Start with a low, controlled tethered hover. Use a managed cable and a clear, unoccupied area. Add cable length and altitude gradually, changing one variable at a time; do not begin at maximum height or in wind.
- Validate failure modes and log results. In a safe test setup, check response to ground-power interruption, converter shutdown, reserve depletion, link and GPS loss, overcurrent, overheating, cable-length limit and tension events. Log ground- and aircraft-end voltage, current, converter temperature, battery state, cable tension and flight warnings.
Increase height, cable length, wind exposure, payload, maneuvering and duration only after the previous test stage is stable. Never test over people or property, and never simulate power failure by cutting or damaging an energized cable.
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Flight-controller and firmware capabilities to verify
Check whether the flight system actually supports the monitoring and responses your design requires:
- Voltage and current telemetry on the relevant power path.
- Battery failsafe and a tested transition to backup power.
- Controlled descent, position-hold and loss-of-GPS behavior.
- Loss-of-control-link behavior, operator alerts and logging.
- Altitude or geofence limits, remote emergency stop and manual override.
- Tether-length or cable-tension monitoring, if those features are part of the installation.
Commercial tether modes can impose special limits. DJI’s Matrice 400 tethered mode specifies horizontal and vertical speed limits, does not support Smart Return-to-Home and defaults to hover as a failsafe behavior. These are product-specific settings, not assumptions to apply to custom firmware. DJI Matrice 400 tethered-system documentation
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.United States: check the rules for the operation
United States; information checked August 18, 2026. Verify current FAA rules and guidance before flying. A tether does not automatically exempt a drone operation from FAA requirements. FAA safety material says most tethered UAS operations remain subject to applicable rules, including Part 107 where relevant, because the tether does not by itself change the aircraft’s regulatory treatment. FAA safety material on tethered UAS
Determine which requirements apply to your operation, including registration, Remote ID, pilot qualification, visual line of sight, airspace authorization, altitude, operations over people, night operations and any necessary waiver. The FAA’s Part 107 waiver page asks applicants to describe the UAS’s in-flight power or energy source and lists a tether as a factor to consider; it does not make tethering a blanket permission or exemption. FAA Part 107 waivers
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A distinct statutory framework may apply to qualifying public-safety operations. The FAA’s checklist for actively tethered public-safety UAS describes eligibility and conditions including organization eligibility, registration and Remote ID; aircraft weight of 55 lb or less excluding the tether; a taut, load-rated tether supplying continuous power; safe control after power or flight-control failure; controlled landing after tether separation; visual line of sight; yielding to other aircraft; no direct operation over non-participating people; and applicable altitude and airspace limits. Do not assume this provision applies to hobbyists, ordinary businesses, demonstrations or every government agency: confirm eligibility and current law and FAA guidance. FAA public-safety tethered-UAS checklist
Outside the United States, check local aviation rules as well as electrical, workplace-safety and public-space requirements. Countries and regions may treat restrained aircraft differently.
Build, adapt or buy?
| Route | Choose it when | Important trade-off |
|---|---|---|
| Build from scratch | The project is experimental or educational, the aircraft is custom, the team can engineer and test high-power electronics, and the test environment is controlled. | Customization and learning, but the team owns structural, electrical, thermal, EMC, flight-safety and support risks. |
| Adapt a supported enterprise drone | The manufacturer documents the power interface and reliability or payload integration matters. | Uses an existing aircraft and integration path, but compatibility and operating behavior are ecosystem-specific. |
| Buy a complete tethered system | Public-facing, security, emergency-response or continuous-deployment work makes support, training, spares and defined operating procedures important. | Higher cost and possible vendor lock-in, in exchange for integrated station, cable management, aircraft interface and support. |
| Use another platform | A cable route, landing area, wind exposure or mobility requirement makes tethering unsafe or impractical. | A battery aircraft, balloon, mast, tower, lighting system or automated dock may better fit the task. |
For operational or public-facing use, compare complete systems on aircraft compatibility, cable length, airborne-module mass, backup-energy behavior, wind rating, repairability, supply requirements, training, warranty and regulatory support—not on an endurance claim alone.
Examples of commercial paths
These are vendor-stated examples, not independent performance comparisons; availability, configuration and prices can change.
- Elistair: Its SAFE-T 2 and LIGH-T 4 stations and KHRONOS dronebox target public safety, security, defense and industrial uses. The company advertises continuous operation up to 24 hours for tethered solutions; SAFE-T 2 lists 110–220 V input, and the company says SAFE-T supports aircraft including DJI M400 and 6S/12S platforms. Pricing was not stated in the reviewed official material. Elistair solutions Elistair SAFE-T station
- Hoverfly Technologies: Sentry and Spectre are dedicated persistent tethered systems for surveillance, communications and security applications. Its store listed a 50-foot tether kit at $124.99 USD, one battery item at approximately $686.55 USD, CONUS basic training at $6,174.85 USD and PowerMount kits at $3,224.99 USD when reviewed; those are vendor-listed prices and may change. Hoverfly tethered UAS Hoverfly store
- DJI Matrice 400 ecosystem: DJI documents a tethered battery and aircraft-specific behaviors. Its UK store listed the TB100C at £1,610 and out of stock when reviewed; that listing gives approximately 977 Wh and 4.87 kg and compatibility with the Matrice 400. Price, stock and availability vary by region. DJI tethered-system documentation DJI UK TB100C listing
- EnduTether G35: The vendor lists configurations for DJI Matrice 30, 300, 350 and 400. Its product page describes a standard 110 m tether, automatic cable control, optional lighting and fiber communications, and claims operation beyond 24 hours. Listed pricing was $9,820–$10,270 USD, varying by model, accessories, payloads, order quantity and application. EnduTether G35
- Foxtech: Its store lists modular T25/T35/T60/T80/T100/T200 and UT35–UT200 systems and a T-3000L tethered power-and-lighting solution. Listed ranges were $8,500–$9,500 USD for T-3000L, $14,999–$52,899 USD for T25–T200 airborne-and-ground systems and $28,899–$109,299 USD for UT35–UT200 complete systems. A listed configuration is not necessarily a complete operational package for every aircraft and payload. Foxtech tethered systems
For a custom build, select test equipment and components by verified specifications rather than a generic parts list: a programmable bench supply, electronic load, calibrated multimeter, DC clamp meter, thermal camera, appropriately rated converter, fuse hardware, locking connectors, abrasion-resistant cable, strain relief, emergency stop, battery analyzer and flight-data logger may be useful. Verify voltage range, current rating, efficiency, cooling, isolation, transient response and approvals for the exact component and application.
Quick Recap
Preflight checks and common symptoms
- Low voltage at the aircraft: Measure at both ends under representative peak load. Check round-trip conductor and connector resistance, cable length, supply regulation and converter input limits.
- Converter resets or false failsafes: Review voltage and current logs during motor load changes; check inrush, transient response, filtering and firmware thresholds.
- Hot connector or cable: Stop operation and inspect current, contact condition, conductor size and thermal rating. Do not treat warmth as acceptable without a validated limit.
- Unstable hover or cable oscillation: Check wind, reel alignment, line tension, snag points and routing near the aircraft’s center of gravity; reduce altitude and land if the disturbance is not understood.
- Compass or navigation warnings: Compare logs with the tether unpowered and powered, inspect high-current cable routing and verify sensor separation and filtering.
- Battery does not charge or take over: Verify the designed charging and power-path logic, battery state and switchover tests on the bench. Do not assume the tether supply will charge a battery merely because both connect to the same bus.
- Unexpected station movement: Stop the flight, secure the ground installation and reassess anchor, ballast, alignment and wind conditions before resuming.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
