Tethered Drone FAQ: Power Systems, Batteries, Cables, Fiber Optics & Applications

A tethered drone system supplies continuous electrical power to a UAV through a lightweight cable connected to a ground power station. A complete system normally includes a ground power unit, tether cable, cable reel or winch, airborne DC/DC power module, and optional fiber-optic communication hardware.

The ground station converts local AC power into high-voltage DC for efficient transmission through the tether. The airborne module then converts that high voltage into the stable low-voltage DC required by the aircraft and, where applicable, its payload.

Please provide: UAV model; battery series count and voltage range; continuous/hover power; peak power; MTOW; actual mission payload; target operating height; desired tether length; operating altitude and temperature; AC input available on site; and whether fiber-optic data transmission is required.

Not necessarily. A system should not be selected to run permanently at its absolute limit. Continuous demand, takeoff and gust peaks, cable loss, environmental derating, payload variation and reserve margin all need to be considered.

Continuous power determines what the system can sustain thermally for long-duration hover and mission operation. Peak power covers short events such as takeoff, climb, wind correction, acceleration and temporary payload demand. Both values are required for correct sizing.

Often yes, provided the aircraft has adequate payload margin, a compatible voltage range, sufficient cooling and a safe electrical/mechanical integration path. The exact UAV model must be reviewed before the airborne module and mounting method are confirmed.

Nominal voltage is only a reference point. The aircraft must also tolerate the voltage present when its battery is fully charged. The airborne module must be configured within the UAV's acceptable input range across the real operating condition, not selected from nominal voltage alone.

Not automatically. The correct output is determined by the aircraft DC bus, battery/BMS behavior and the chosen parallel-power architecture. Setting the module simply to the nominal battery voltage can be incorrect because the aircraft normally operates over a wider voltage range.

In many TethPower integrations, yes. The original battery can remain connected to the aircraft power bus as a backup and transient-power buffer. However, some UAV platforms use different power-path designs, so the connection method must be confirmed project by project.

Current sharing is not a fixed 50/50 split. It depends on the instantaneous voltage of the airborne module, the battery terminal voltage, load demand, wiring resistance and any power-path control. During normal operation the tethered module is usually designed to carry most of the continuous load, while the battery may support transient demand.

Not necessarily, and maintaining 100% state of charge is not automatically the design objective. In many architectures the battery is preserved as emergency reserve rather than actively charged to full while flying. Actual battery behavior depends on voltage setpoint, BMS logic and power-path design.

A correctly engineered system must prevent the battery from being driven beyond its permitted voltage or charging limits. However, 'the battery can never be overcharged' should not be assumed for every parallel connection. The output setpoint, BMS, reverse-current path and any blocking or power-path circuitry must be verified for the specific UAV.

Backfeeding means current flows from one source into another source instead of only toward the UAV load. For example, if the airborne module bus voltage is higher than the battery terminal voltage and the electrical path allows it, current may flow toward the battery. This is why parallel integration must be designed, not improvised.

Not without confirming how that BMS behaves in the actual aircraft. A BMS may provide important protection, but the complete power architecture still needs to be reviewed. TethPower does not treat an unknown BMS as the only protection layer in a custom integration.

For the same transmitted power, higher voltage allows lower current. Lower current reduces resistive loss and makes it possible to use a lighter cable, which is critical because the aircraft must lift the tether.

Voltage drop is the reduction in voltage between the ground station and the airborne end caused mainly by cable resistance and current. In simplified DC terms, the drop is approximately current multiplied by the loop resistance of the complete outgoing-and-return path.

Loop resistance is the total resistance of the positive and negative current paths together. It is the relevant resistance used when estimating tether voltage drop and resistive heating.

Only within the approved limits of the ground station, tether insulation, connectors and airborne-module input range. Raising voltage is an engineering adjustment, not a universal fix. Excessive input voltage can damage equipment or violate safety margins.

It can. Longer cable increases resistance, heat and voltage drop. If the airborne-module input falls too low or cable temperature/current limits are reached, the usable power must be reduced or the system redesigned with a different transmission voltage or conductor.

No. Additional length is required for routing from the reel, cable angle, sag, wind, ground clearance and safety margin. A target operating height therefore normally requires more cable than the vertical height alone.

It stores, pays out and retrieves the tether while controlling cable handling during climb, hover and descent. Depending on the model, it may provide motorized retrieval, passive payout, manual control, speed control and constant-tension functions.

Constant-tension control keeps the tether pull within a planned range so the cable does not become excessively slack or pull the aircraft downward too strongly. The correct tension depends on aircraft size, tether weight, wind and mission.

It converts site AC input into controlled high-voltage DC for tether transmission and may also integrate input protection, alarms, emergency stop, cooling, reel control, status monitoring and optional fiber-optic hardware.

Lower-power portable systems often use single-phase input, while higher-power industrial systems commonly require three-phase AC. The final choice depends on output power, local site power, generator capacity, portability and electrical standards.

Yes, if the generator provides the required voltage, phase, frequency, continuous capacity, transient capacity, grounding and power quality. Generator sizing should include conversion losses, auxiliary loads and reserve margin rather than matching only the nominal kW rating.

Not necessarily. The generator must supply the input side of the complete system, including conversion loss, startup/transient demand and auxiliary equipment. It should be selected with suitable reserve and stable voltage/frequency.

Depending on the model, protection may include overvoltage, undervoltage, overcurrent, short circuit, reverse connection, overtemperature, abnormal input, output fault and alarm functions. Exact protection features are model-specific.

Only modules specifically designed and tested for current sharing should be paralleled. Two standalone modules cannot be assumed to share current correctly simply because their individual voltage ratings are similar.

Fiber provides high-bandwidth, stable data transmission with strong immunity to radio-frequency and electromagnetic interference. It is useful for command, telemetry, Ethernet data, HD video and other mission data.

Yes. A hybrid power-and-fiber tether can transmit high-voltage DC and optical signals in the same cable, simplifying cable management and supporting continuous power plus reliable data transmission.

Usually no. Unless the aircraft or payload has a compatible native optical interface, an airborne optical/electrical conversion module is required to convert the fiber signal into interfaces the UAV, flight controller, camera or payload can use.

Depending on the converters and system design, fiber can transport Ethernet/network data, serial data, telemetry, video and control-related interfaces such as SBUS through suitable conversion hardware. The exact protocol and connector must be confirmed.

Yes, if the network/conversion architecture and bandwidth are designed for both. Multiple data streams can be transported over the same optical link, but the required switches, converters and interfaces must be defined.

No digital video/control system is literally zero-latency. Fiber itself adds very little delay, but total latency also comes from cameras, encoders, network devices, decoders, controllers, displays and software.

The optical data path is not affected by RF interference in the same way as a wireless link. However, GNSS, onboard electronics and any remaining radio links can still be affected. Fiber reduces one major dependency but does not make the entire aircraft immune to interference.

In some projects, yes, through appropriate conversion or bridging hardware. Compatibility depends on the controller, flight-control protocol, video path and whether the aircraft permits the required interface.

No. The power supply may support continuous operation for extended periods, but actual flight endurance is also limited by motors, ESCs, propellers, bearings, cooling, flight-control behavior, weather, payload and maintenance requirements.

Not automatically. '24/7 capable power delivery' describes the ground-power architecture, not a guarantee that every aircraft can stay airborne continuously without inspection. UAV thermal limits and maintenance intervals must be respected.

Yes. Removing the battery-endurance limit can expose thermal limits that were less visible during short battery flights. Motor, ESC and connector temperatures should be monitored during extended missions.

It can. Power electronics may need thermal derating when ambient temperature, internal temperature or airflow exceeds the design condition. Installation clearance and cooling are part of system selection.

Yes. Lower air density can reduce cooling performance and change aircraft propulsion efficiency. High-altitude projects should be evaluated for power, thermal margin, payload and flight performance rather than using sea-level assumptions.

Operators should periodically check cable condition and temperature, connectors, airborne-module temperature, battery status, winch behavior, motor/ESC temperature, weather, alarms and mechanical fasteners.

Yes. Continuous power does not make the aircraft unattended. A trained operator or team must monitor the UAV, tether, ground station, weather, flight area and emergency conditions.

Yes. Proper protective grounding and site electrical safety are essential for high-voltage tethered equipment. The grounding method must follow the product manual and local electrical regulations.

Persistent monitoring requires the aircraft to remain above one area for long periods. Continuous power reduces battery-change interruptions, while fiber can provide a stable wired path for EO/IR video, control and command-center data.

Yes, if the selected gimbal or payload supports both and its power, interfaces, bandwidth, mounting and control requirements are integrated into the system.

Selection should consider the required illuminated area, operating height, lumen output, beam pattern, ground illuminance target, payload weight, power consumption, wind and whether the light direction must be adjustable.

No. Useful illumination also depends on mounting height, beam angle, optical efficiency, target distance and ambient light. A well-matched beam can be more useful than a larger lumen number with poor light distribution.

It combines continuous electrical power with a ground-fed water hose. The power tether reduces battery-change downtime while the water tether supplies cleaning fluid or water to the airborne spray system.

Pressure is lost through hose length, elevation, fittings, bends, filters and flow resistance. Cleaning systems should therefore be evaluated from the pump to the nozzle rather than by the pump's maximum pressure alone.

Yes. Hose weight, water column, drag and hose tension all affect the aircraft. These loads must be included in the payload and flight-stability calculation, especially at greater heights.

Yes. Long-duration power is well suited to communication payloads that need to remain at altitude. Payload weight, power consumption, antennas, cooling, data backhaul and local spectrum rules must all be considered.

Yes. Tethered power can support controlled endurance, hover, propulsion and flight-control testing when the aircraft electrical architecture and test envelope are compatible. The tether should be treated as part of the test setup, including mechanical and safety effects.

The same aircraft can be used with different payloads, heights, cable lengths, site power and operating environments. Final pricing depends on the actual ground station, airborne module, tether, winch, interfaces, fiber, customization, testing and delivery scope.

A formal quotation normally lists the selected ground power unit, airborne module, tether length, reel/winch, connectors, accessories, documentation, packing, trade term, lead time, warranty and any optional services. Third-party UAVs and payloads are included only when clearly listed.

Yes, many projects can be customized in output voltage, power level, tether length, connector, mechanical mounting, data interface, appearance and system configuration. Feasibility, MOQ, cost and lead time depend on the requested changes.

Integration can be evaluated when complete electrical, mechanical and interface specifications are available. Third-party payload selection and certification are not automatically included in the standard tethered-power scope.

Project systems can be powered and function-tested according to the agreed scope. When the customer's aircraft is not available to TethPower, final aircraft-level integration and flight validation must be completed with the customer's actual UAV after delivery.

Yes. Support may include wiring review, video guidance, parameter confirmation, startup assistance, fault analysis and operating advice. Complex integrations may require on-site support or return-to-factory testing.

No. Certification and test documentation are model-specific. Required CE, EMC, safety, IP, environmental, transport or local compliance documents should be confirmed before ordering.

The local operator, customer or authorized local partner is normally responsible for aviation permission, airspace approval, operator licensing, spectrum requirements and other local regulatory obligations unless separately contracted.

Send the UAV model or target platform, battery voltage range, continuous and peak power, MTOW, mission payload, required operating height, tether length, site AC input, fiber/data requirements, operating environment, quantity, destination and expected schedule to TethPower.