Wie lange halten die Batterien von Unterwasserdrohnen? ROV-Laufzeit nach Missionstyp erklärt

Battery-powered underwater drones can operate for several hours per charge, but there is no single runtime that applies to every ROV or every mission. Current manufacturer specifications show just how wide the difference can be: QYSEA rates the FIFISH V-EVO for up to four hours while hovering but about one hour at full mobility, while Blue Robotics rates the BlueROV2 at about two hours of normal use and four hours of light use with its specified battery configuration.

The reason is simple: underwater drone batteries supply a changing power load, not a fixed one. A vehicle filming slowly in calm water has a very different energy profile from the same type of ROV holding position against current, running sonar, or operating a manipulator.

For operators and ROV developers, the useful question is therefore not only “How many hours does the battery last?” It is “How much usable energy does this mission require, and can the battery safely deliver both the average and peak power the vehicle needs?”

How Long Do Underwater Drone Batteries Last in Real-World Use?

Most compact battery-powered ROVs are designed for multi-hour operation, but published runtime figures are only meaningful when the operating conditions are also known. A manufacturer may specify normal use, light use, hovering, full movement, or another duty profile, and those figures should not be treated as interchangeable.

For example, three current ROV specifications illustrate the range:

ROV	Published Battery Runtime	Operating Context
QYSEA FIFISH V-EVO	Up to 4 hours	About 4 hours hovering; about 1 hour full mobility
Blue Robotics BlueROV2	About 2 hours normal use	About 4 hours under light use
Blueye with 216Wh High Capacity Battery	Up to 5 hours	Normal runtime; varies with use and equipment configuration

These figures come from the respective manufacturers and demonstrate why a single “four-hour ROV” label can hide important differences in actual mission endurance.

Rated Runtime vs Actual Dive Time

Rated runtime is usually measured under a defined operating profile. Actual dive time includes everything the vehicle must do from launch to recovery.

A practical mission may include:

• descent to the work site;
• transit from the launch point to the target;
• inspection, filming, measurement, or intervention;
• station-keeping while data is collected;
• repositioning between inspection points;
• ascent and recovery;
• an energy reserve for delays or changing conditions.

Thinking in mission phases is especially useful because the task-execution phase may consume energy very differently from descent or slow transit. Your second reference similarly separates deployment, transit, task execution, and recovery when considering practical mission endurance.

An ROV that needs 90 minutes for the actual inspection should therefore not be specified around exactly 90 minutes of theoretical battery runtime. Battery capacity has to support the full deployment profile and the project’s required reserve.

Why Two Similar ROVs Can Have Very Different Endurance

Battery watt-hours are important, but they are only one part of runtime.

Two ROVs carrying batteries with similar energy capacity may still consume that energy at different rates because of:

• vehicle size and hydrodynamic drag;
• thruster number, layout, and efficiency;
• operating speed;
• tether diameter and deployed length;
• buoyancy and trim;
• payload mass and drag;
• lighting output;
• sonar and navigation equipment;
• onboard processors;
• manipulators or other powered tools.

ROV architecture matters because thruster configuration determines how the vehicle moves and holds position, while the tether itself introduces drag into the system. Your Deep Trekker reference likewise identifies thruster configuration as central to propulsion and identifies neutrally buoyant tether as a way to reduce drag in current.

That is why underwater drone batteries should be evaluated against an actual vehicle power budget rather than by comparing amp-hour ratings alone.

ROV Runtime by Mission Type

Mission type is one of the strongest predictors of real-world battery demand. The same ROV can operate efficiently during slow visual inspection and consume considerably more power when asked to travel quickly, fight current, or run multiple accessories at once.

Mission Type	Typical Power Demand	Main Battery Loads	Runtime Implication
Slow visual inspection	Low to moderate	Thrusters, camera, lights	Often closer to normal or light-use runtime
Station-keeping in calm water	Low to moderate	Position-control thrusters, camera	Efficient if buoyancy and trim are well set
Station-keeping in current	Mäßig bis hoch	Continuous thruster correction	Runtime can fall substantially
Search and wide-area transit	Mäßig bis hoch	Sustained propulsion, lights, navigation	Higher average power demand
Sonar inspection	Mäßig bis hoch	Thrusters, sonar, computer, camera	Auxiliary loads add to propulsion demand
Manipulator work	Variable to high	Thrusters, manipulator, lights, sensors	Power profile depends heavily on tool duty cycle

The table is intentionally qualitative. Giving a fixed number of hours for each mission without knowing the ROV, current, payload, speed, and battery would create false precision.

Visual Inspection, Filming and Station-Keeping

Slow visual inspection can be relatively energy-efficient when the ROV is properly balanced and working in mild conditions.

A hull survey, tank inspection, aquaculture check, or close-range video task may involve slow movement followed by periods of hovering. During these phases, propulsion demand can remain lower than during continuous high-speed transit.

The QYSEA FIFISH V-EVO provides a useful published example of this difference: its specification separates approximately four hours of hovering from about one hour under full mobility. The vehicle and battery have not changed; the propulsion duty cycle has.

Station-keeping becomes a different energy problem when current increases. Instead of making occasional corrections, the thrusters may need to provide continuous force simply to keep the camera or sonar aimed at the target.

Search, Transit and Current-Heavy Missions

Search patterns and long transit legs place more emphasis on propulsion.

The effect becomes stronger when the vehicle works in rivers, tidal areas, harbors, or offshore environments. Water acts on both the ROV and its tether, so higher current can require sustained thrust even when vehicle speed over the bottom is modest.

Tether management matters here. A longer or larger-diameter tether presents more area to moving water, increasing the load the vehicle must overcome. Real ROV users repeatedly raise current and tether drag as practical concerns, particularly when operating around wrecks or at greater horizontal distance.

Aus diesem Grund a Batteriehersteller or ROV integrator needs more than a desired “four-hour runtime.” Current speed, tether configuration, transit distance, and expected thruster duty are engineering inputs.

Sonar, Manipulator and Multi-Sensor Operations

An ROV does not spend all its energy on movement.

Cameras, LED lights, sonar, navigation electronics, onboard computers, communications hardware, and manipulators create auxiliary electrical loads. On a sensor-heavy inspection platform, these loads may remain active for much of the mission.

Sonar becomes especially valuable in turbid or low-visibility water, where optical imaging alone may not provide usable navigation or inspection data. Modern ROV platforms can also combine sonar with DVLs, USBL positioning, inertial sensors, and onboard processing. Your first reference describes sonar, positioning, cameras, lighting, and navigation as integrated parts of professional ROV operations.

The correct calculation therefore uses total average mission power, not thruster power alone.

MANLY Battery Platforms for Custom Underwater Drone Batteries

MANLY Battery offers LiFePO4 platforms that can serve as electrical starting points when developing custom underwater drone batteries. The final pack specification still needs to be matched to the ROV’s voltage, average and peak load, battery compartment, BMS requirements, environmental design, and charging architecture.

An important distinction is enclosure qualification. MANLY’s catalog batteries may carry IP65 or IP67 enclosure specifications, but an IP classification under IEC 60529 is an ingress-protection classification; it is not by itself a subsea pressure-depth rating. A battery intended for an ROV must be installed within, or engineered as part of, a system validated for the vehicle’s actual pressure and depth requirements.

MANLY 24V 20Ah LiFePO4 Battery — 512Wh Reference Platform

The MANLY 24V 20Ah LiFePO4 Battery uses a 25.6V nominal configuration with 20Ah rated capacity, giving 512Wh of nominal stored energy.

Its published electrical specification includes:

• 25.6V nominal voltage;
• 20Ah rated capacity;
• 512Wh energy;
• 20A maximum continuous discharge;
• BMS protection for overcharge, over-discharge, overcurrent, overvoltage, short circuit, and over-temperature;
• IP67 enclosure classification.

For a compact 24V ROV project, 512Wh provides a useful engineering reference when the vehicle’s continuous current requirement remains within the configured battery limits.

The value of the 512Wh figure is not that it guarantees a particular number of dive hours. It gives the engineering team a defined energy budget that can be compared with the ROV’s measured or estimated average wattage.

Beispielsweise hypothetical ROV averaging 200W would have a simple theoretical energy calculation of:

512Wh ÷ 200W = 2.56 hours

That is not a promised field runtime. Real usable time will also depend on BMS limits, operating temperature, battery condition, actual duty cycle, reserve requirements, and the vehicle’s electrical efficiency.

MANLY 24V 50Ah Robot Battery — 1,280Wh Higher-Capacity Platform

The MANLY 24V 50Ah Robot Battery is a LiFePO4 platform designed for robotic applications where more onboard energy and higher current capability are required.

Its published specification includes:

• 25.6V actual nominal battery voltage;
• 50Ah capacity;
• 1,280Wh energy;
• 50A maximum continuous discharge;
• 100A peak discharge for 1–3 seconds;
• IP65 enclosure specification;
• optional RS485, RS232, or CANBus communication;
• customizable dimensions;
• customizable housing;
• customizable cables and connectors.

For an ROV developer, the significance of the 50A continuous and 100A short-duration ratings is different from the significance of the 1,280Wh capacity.

Energy capacity determines how much energy is stored. Current capability determines whether the battery can supply the load demanded at a particular moment.

An ROV with a large battery can still have an unsuitable power system if the BMS, cells, wiring, connector, or fuse architecture cannot support the required current.

Custom Battery Packs for ROV Voltage, Current and Runtime Requirements

Ein Brauch ROV battery should start with the vehicle specification rather than with a catalog battery size.

Before developing underwater drone batteries, useful engineering inputs include:

• nominal and allowable operating voltage;
• target mission duration;
• measured or estimated average power;
• maximum continuous current;
• kurzzeitiger Spitzenstrom;
• thruster configuration;
• auxiliary equipment load;
• maximum battery dimensions and weight;
• connector and cable requirements;
• BMS-Schutzschwellenwerte;
• required battery communication;
• charging strategy;
• temperature range;
• mechanical and environmental requirements.

MANLY can customize robot battery voltage, capacity, dimensions, BMS charge and discharge current, connectors, enclosures, and wiring. Selected robot configurations also support CAN Bus, RS485, and RS232 communications.

Communication can be important when the vehicle controller needs state-of-charge, voltage, current, temperature, alarms, or charge information. The exact protocol still has to match the ROV controller; having a CAN or RS485 physical interface does not automatically make two devices interoperable.

For an OEM project, a battery manufacturer should therefore treat the cells, BMS, controller interface, wiring, charging system, and mechanical enclosure as one integrated power architecture.

What Reduces Underwater Drone Battery Runtime?

Thruster demand is often the largest variable in underwater drone runtime, but it is not the only one. Current, tether drag, payloads, lighting, sonar, vehicle balance, temperature, and operating technique can all change average power consumption.

Thruster Load, Speed, Current and Tether Drag

Propulsion power changes continuously.

Slow maneuvering may require only a fraction of available thrust. Sustained high-speed movement or holding position against current requires the thrusters to work much harder.

Blue Robotics illustrates this difference directly in its BlueROV2 runtime specification: about two hours under normal use compared with about four hours under light use. In technical discussions around ROV power calculations, Blue Robotics also notes that assuming every thruster runs continuously at maximum output does not represent typical operation.

Tether drag adds another external load. More deployed tether means more cable exposed to moving water, so tether diameter, buoyancy, route, and current direction can all affect the propulsion required to maintain position.

Lights, Sonar, Cameras and Manipulators

Auxiliary equipment consumes part of the same energy budget.

A basic observation ROV may run a camera, controller, communications hardware, and moderate lighting. A professional inspection platform may add imaging sonar, positioning sensors, additional lights, onboard computing, and a manipulator.

The correct power model is therefore:

Average mission power = propulsion load + electronics + sensors + lighting + tools + conversion losses

Not every device operates at maximum power all the time, so using duty cycle is more realistic than adding every nameplate maximum together.

For example, a manipulator may draw substantial power when moving but almost none while idle. Lights may run continuously during a dark-water inspection. Sonar and navigation electronics may remain powered throughout the dive.

That operating pattern is what converts a component list into a realistic battery requirement.

Water Temperature, Buoyancy and Vehicle Trim

Battery and vehicle efficiency also depend on physical operating conditions.

Temperature can affect lithium battery performance, particularly as conditions move away from the cells’ preferred operating range. Battery selection should therefore be based on the actual thermal environment rather than room-temperature capacity alone.

Vehicle balance is equally important. A well-trimmed ROV that is close to neutral buoyancy does not have to spend as much propulsion energy continuously correcting depth or attitude.

Blue Robotics specifically recommends setting the BlueROV2 close to neutral buoyancy for battery life and handling; a vehicle that is excessively positive or negative must use more thrust to maintain depth.

Depth itself should not be treated as a simple “deeper equals faster battery drain” relationship. The more relevant factors are the energy required for descent and ascent, tether behavior, pressure-system requirements, current at working depth, and how long the ROV must travel before reaching the task area.

How to Calculate ROV Runtime from Battery Capacity and Power Draw

The basic theoretical calculation is straightforward:

Runtime (hours) = usable battery energy (Wh) ÷ average ROV power (W)

The difficult part is determining realistic usable energy and average mission power.

Convert Voltage and Amp-Hours into Watt-Hours

Amp-hours alone do not tell you how much energy a battery stores.

Use:

Watt-hours (Wh) = nominal voltage (V) × amp-hours (Ah)

Zum Beispiel:

• 25.6V × 20Ah = 512Wh
• 25.6V × 50Ah = 1,280Wh

This is why watt-hours are more useful than amp-hours when comparing batteries at different voltages.

A 20Ah battery at one voltage does not contain the same energy as a 20Ah battery at another voltage.

Estimate Average Mission Power, Not Just Peak Power

Peak power answers one engineering question: Can the battery safely support the highest expected load?

Average power answers another: How quickly will the stored energy be consumed?

Beides ist wichtig.

Suppose an ROV has six or eight thrusters. Adding the maximum electrical rating of every thruster and assuming that total load persists throughout the entire dive will normally overstate mission energy consumption. Conversely, sizing the battery from calm-water cruising alone can understate what the pack must supply during current-heavy maneuvering.

Blue Robotics technical guidance makes the same distinction: actual battery life depends strongly on how aggressively the vehicle operates, and all thrusters running at maximum power simultaneously is not a typical continuous condition.

A more useful engineering worksheet looks like this:

Laden	Average Power	Time or Duty Cycle	Mission Energy
Thrusters	Measured/estimated	Mission dependent	W × hours
Camera and control	Measured/estimated	Usually continuous	W × hours
Lichter	Measured/estimated	As required	W × hours
Sonar	Measured/estimated	As required	W × hours
Manipulator	Measured/estimated	Intermittierend	W × hours
Other payloads	Measured/estimated	Mission dependent	W × hours

Add the expected watt-hours for each load to build a mission energy budget.

Add Operational Reserve and Validate with Field Data

The calculated runtime should not be treated as the point at which the battery is expected to reach empty.

The required reserve depends on the vehicle, mission risk, recovery method, BMS limits, environmental uncertainty, and the operator’s procedures. A vehicle inspecting a tank beside an access platform has a different recovery profile from an offshore ROV operating at substantial distance from its launch point.

After prototype deployment, measured data should replace assumptions wherever possible.

Useful records include:

• average current;
• Spitzenstrom;
• Batteriespannung;
• mission duration;
• starting and ending state of charge;
• water temperature;
• current conditions;
• tether length deployed;
• payload configuration;
• mission phase.

Several dives under representative conditions can produce a much more useful power profile than an estimated runtime based only on catalog specifications.

That measured profile also gives a battery manufacturer a stronger basis for deciding whether additional capacity, different current capability, revised BMS settings, or another pack architecture is appropriate.

Choosing Underwater Drone Batteries for Your ROV Mission

The right underwater drone battery is not simply the pack with the largest Ah rating. Voltage compatibility, watt-hours, continuous current, peak current, BMS behavior, size, weight, charging, communication, and pressure-system integration all need to work together.

Li-ion, LiPo or LiFePO4?

There is no single lithium chemistry that fits every ROV.

Commercial ROV systems already demonstrate this diversity. Blue Robotics offers both lithium-ion and lithium-polymer battery approaches for the BlueROV2, while MANLY’s robotic platforms use LiFePO4.

Selection should be based on the application:

Lithium-Ionen:
Often considered where high energy storage relative to pack mass and volume is important. The exact energy and discharge characteristics depend on the cell chemistry and construction.

Lithium-polymer:
Common in systems requiring compact packaging and high discharge capability. Pack design, charging controls, mechanical protection, and thermal management must still match the application.

LiFePO4:
Well suited to many industrial systems where cycle life, power capability, and thermal behavior are important design priorities. Published comparative battery research shows meaningful chemistry-dependent differences in thermal response, reinforcing the need to choose chemistry as part of the system design rather than by capacity alone.

MANLY Battery uses LiFePO4 in its current robot battery platforms, including the 24V 20Ah and 24V 50Ah configurations discussed above.

Voltage, Continuous Current, Peak Current and BMS

A lithium battery for an ROV has to satisfy several electrical constraints simultaneously.

Stromspannung must match the vehicle’s permitted electrical range.

Dauerstrom must cover sustained propulsion and auxiliary loads without exceeding the battery, BMS, wiring, or connector limits.

Spitzenstrom must accommodate short load increases such as rapid maneuvering or simultaneous thruster demand where the ROV architecture permits it.

The BMS must protect the cells while remaining compatible with normal vehicle operation. Overcurrent protection that trips below a legitimate propulsion peak, for example, would interrupt the mission even if the battery stores plenty of energy.

For connected systems, communication requirements may include state of charge, voltage, current, temperature, warnings, and charger coordination. These functions should be defined before a custom pack is finalized rather than added after the ROV electronics have already been designed.

Battery Swaps, Surface Power and Field Logistics

Long mission capability does not always require one very large onboard battery.

There are three common architecture choices:

1. More onboard energy for longer intervals between recovery.
2. Swappable batteries so a vehicle can return to service quickly.
3. Surface power when continuous operation is more important than completely self-contained onboard power.

Blue Robotics, for example, specifies that its BlueROV2 battery can be changed in about 30 seconds and also supports a separate surface-power architecture for continuous operation.

Surface power changes the energy problem fundamentally. Instead of carrying the full mission energy onboard, electrical power travels through the tether from the surface. That removes the normal onboard battery-runtime limit, although actual deployment duration still depends on equipment ratings, crew operations, maintenance, tether management, and the surface power source.

Questions about onboard versus surface power also appear repeatedly in ROV user communities, particularly among builders trying to balance tether losses, vehicle weight, current demand, and endurance.

The second reference you supplied reaches the same useful distinction: battery-powered and surface-powered ROVs have fundamentally different endurance models.

For repeated field work, uptime may therefore depend as much on pack swapping, charging logistics, and spare-battery planning as on the runtime of one battery.

Underwater Drone Battery FAQs

Does a Bigger Battery Always Give an ROV Longer Runtime?

More watt-hours generally provide more stored energy, but a larger battery does not automatically produce a proportional increase in ROV runtime. The added pack may change vehicle weight, buoyancy, dimensions, and trim, while the battery still has to meet voltage and current requirements. Compare W, not Ah alone, and evaluate the complete mission power budget. For custom underwater drone batteries, mechanical integration should be considered at the same time as electrical capacity.

Can an Underwater Drone Run Continuously from Surface Power?

Yes. A properly designed tethered ROV can receive electrical power from a topside supply instead of relying only on an onboard battery. Blue Robotics offers a surface-power configuration for continuous BlueROV2 operation.

The system requires more than connecting a charger cable to the vehicle. Tether conductor size, transmission voltage, voltage drop, conversion electronics, electrical protection, subsea connectors, and the ROV’s power architecture must all be engineered for the required load.

How Long Does an Underwater Drone Battery Last Before Replacement?

Runtime per charge and battery service life are different specifications. Runtime describes how long one mission can operate before recharging; service life describes how the battery retains usable capacity over repeated charge-discharge cycles and calendar aging.

Cycle life depends on cell chemistry, depth of discharge, temperature, charge conditions, current demand, storage state, and the manufacturer’s end-of-life criterion. MANLY’s current 24V 20Ah LiFePO4 specification states 6,000 cycles at 80% depth of discharge under its specified conditions.

Battery health should still be assessed against the actual application rather than assuming every field pack will reproduce a catalog cycle figure.

Is Watt-Hour Capacity More Useful Than Amp-Hours for an ROV?

Yes, when comparing batteries with different voltages. Watt-hours represent stored energy because they combine voltage and amp-hour capacity:

Wh = V × Ah

A 25.6V 20Ah pack stores 512Wh, while a 25.6V 50Ah pack stores 1,280Wh. Amp-hours alone cannot show that difference when voltage changes. Current ratings must then be checked separately because watt-hours describe energy capacity, not how much current the pack can safely deliver at once.

What Information Should I Give a Battery Manufacturer for a Custom ROV Battery?

Start with the ROV’s nominal voltage, permitted voltage range, desired mission duration, measured average power, continuous and peak current, battery-space dimensions, weight limits, connector, charging method, temperature range, BMS requirements, and communication protocol.

Also describe the mission: visual inspection, high-current station-keeping, sonar survey, manipulation, or another duty profile. These details allow the battery manufacturer to translate required runtime into energy, current, BMS, mechanical, and integration requirements instead of selecting a pack from Ah capacity alone.

Abschluss

The useful answer to “How long do underwater drone batteries last?” is not a single number. Published ROV specifications already show that one vehicle can deliver very different runtimes depending on whether it is hovering, cruising lightly, or operating at high propulsion demand.

For visual inspection and slow observation, efficient maneuvering and neutral buoyancy can help keep average power relatively low. Search patterns, sustained transit, current-heavy station-keeping, sonar, manipulators, and other payloads increase the mission energy requirement.

Start with watt-hours to establish stored energy, then verify voltage, continuous current, peak current, BMS behavior, environmental requirements, and the complete mission duty cycle.

For OEM ROV development, MANLY Battery’s 24V 20Ah 512Wh LiFePO4 battery and 24V 50Ah 1,280Wh robot battery provide two existing electrical reference platforms. MANLY can also develop custom battery configurations around the project’s voltage, capacity, current, BMS, communication, connector, wiring, and mechanical requirements. The final underwater power system should then be engineered and validated for the ROV’s actual operating depth, enclosure, payload, and mission profile.

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