¿Cómo se comparan los drones submarinos en términos de duración de la batería?

Un underwater drone battery may support anything from roughly an hour of exploration in a compact recreational ROV to several hours of professional inspection work, while large autonomous underwater vehicles can remain operational for tens of hours. The difference comes from much more than battery size: propulsion load, water current, lighting, payloads, vehicle efficiency and the way power is supplied all affect useful mission time.

That makes headline battery life figures difficult to compare directly. A four-hour figure measured in still water does not describe the same operating conditions as four hours of inspection work against a current with lights, sonar and tools running.

This guide compares real manufacturer specifications, explains what changes underwater drone battery life in practice and shows how OEMs can translate a required mission duration into a suitable batería de litio specification.

How Long Does an Underwater Drone Battery Last?

For battery-powered underwater drones, a useful broad range is around one to five hours for many compact and professional ROVs. Autonomous underwater vehicles occupy a different category altogether and may be engineered for missions lasting tens of hours.

The term “underwater drone” itself covers several types of vehicle. A remotely operated vehicle, or ROV, is controlled from the surface and normally remains connected by a tether. An autonomous underwater vehicle, or AUV, carries out a pre-programmed or adaptive mission without continuous pilot control. The UK’s National Oceanography Centre makes the same distinction between tethered ROVs and independently operating AUVs.

Compact Underwater ROVs: Around One to Four Hours

Small recreational and light-inspection ROVs show how wide the runtime range can be even before moving into professional equipment.

CHASING DORY uses an internal 4,800 mAh battery and is rated for up to 60 minutes of exploration. GLADIUS MINI S moves to two 4,800 mAh batteries and advertises up to four hours of battery life.

Those figures should not be interpreted simply as “twice the battery means four times the runtime”. Different vehicles have different motors, hydrodynamics, electronics, lighting and operating speeds. Battery capacity is only one part of the energy equation.

CHASING’s newer DORY Explore illustrates this particularly well. Its published runtime ranges from around 35 minutes at full throttle to as much as four hours with the lights off in still water. The same underwater drone battery can therefore produce very different mission times depending on how the vehicle is operated.

Professional Battery-Powered ROVs: Roughly Two to Five Hours

Professional ROVs often sit in the two-to-five-hour range when operating from onboard batteries, although the test conditions and configuration matter.

Blue Robotics rates the BlueROV2 at about two hours under “normal use” and four hours under “light use” with the battery specified on its current vehicle page. Blueye’s 216 Wh high-capacity battery is rated for up to five hours of normal runtime across compatible Blueye ROVs. CHASING M2 S uses a 97.68 Wh battery and is rated for up to four hours, with the manufacturer explicitly noting that actual duration varies with operating conditions.

The important point is not that one of these figures is inherently more impressive. Each reflects a different vehicle, operating profile and battery system. For inspection planning, “normal use”, accessory load and the ability to replace the battery are often more useful than the largest published runtime number.

AUV Endurance Can Run Into Tens of Hours

AUV battery design works on a different scale.

KONGSBERG’s HUGIN platform, for example, specifies battery technology capable of up to 100 hours of endurance at four knots. HUGIN is a large industrial and scientific AUV platform designed for applications such as geophysical surveys, sonar work and autonomous seabed data collection, so that figure should not be compared directly with a portable camera ROV.

For long-range AUVs, energy density affects not merely how long the vehicle stays underwater, but how much territory or seabed can be surveyed before recovery.

A recent Lobster Robotics battery project demonstrates that connection. A higher-energy-density pack developed for its autonomous underwater mapping vehicle reportedly increased battery life by approximately 60% without a meaningful increase in vehicle size, allowing more seabed to be surveyed in each deployment.

Underwater Drone Battery Life Compared Across Popular ROVs

Published specifications become more useful when the battery architecture and test wording are read alongside the headline runtime.

CHASING DORY
4,800 mAh internal battery | up to 60 minutes

DORY represents the compact end of the market. Its low weight and integrated power system suit short exploration and filming sessions, but its one-hour maximum also shows why mission duration matters when selecting a small underwater ROV.

GLADIUS MINI S
Two 4,800 mAh batteries | up to 4 hours

The dual-battery arrangement gives GLADIUS MINI S a substantially longer published operating window for underwater exploration, video capture and light inspection. The four-hour figure remains an “up to” specification rather than a guaranteed duration under every current, speed and accessory load.

CHASING M2 S
97.68 Wh swappable battery | up to 4 hours

M2 S provides a particularly useful comparison because its battery is expressed in watt-hours. The standard 97.68 Wh unit is removable, and CHASING also offers a higher-capacity battery option for longer operations. That makes battery replacement part of the mission-planning equation rather than forcing every task into one fixed onboard capacity.

BlueROV2
15.6 Ah battery reference | approximately 2 hours normal use / 4 hours light use

BlueROV2 clearly separates normal and light-use runtime rather than presenting only one maximum figure. Its battery can also be changed in roughly 30 seconds, making turnaround time relevant for repeated dives.

Blueye High Capacity Battery
216 Wh | up to 5 hours of normal runtime

Blueye takes a modular approach: the higher-capacity 216 Wh pack extends the operating window while remaining field-swappable and compatible with the company’s ROV range. This is useful for inspection teams that want longer individual deployments without changing the complete vehicle platform.

FIFISH E-GO
69.12 Wh × 2 | around 1–4 hours depending on operating conditions

FIFISH E-GO uses two lithium-ion battery modules and supports hot swapping. QYSEA specifies approximately 2.5 hours under its standard intermittent static-water test and a broader 1–4-hour range depending on the working environment. Importantly, hot-swapping is performed in air rather than underwater.

“Up to” Runtime Versus Normal-Use Runtime

“Up to four hours” and “four hours of normal operation” are not equivalent claims.

Manufacturers may establish maximum runtime under relatively light propulsion loads, still water or reduced accessory use. BlueROV2’s published distinction between roughly two hours of normal use and four hours of light use makes the difference easy to see. CHASING also states that M2 S runtime varies with operating conditions.

When comparing an underwater drone battery, look for the test description as well as the number. A specification that explains what the vehicle was doing provides more planning value than an isolated maximum.

Replaceable and Hot-Swappable Batteries

A replaceable battery can make a shorter individual runtime much less restrictive.

BlueROV2 batteries can be changed rapidly between deployments. Blueye batteries are designed for field swapping. FIFISH E-GO goes further with a dual-battery architecture that allows one module to be replaced without shutting the system down, although the replacement must take place out of the water.

For repeated inspection dives, the operational question therefore becomes:

How long can the team keep the ROV working across a complete shift, rather than how long can one battery remain underwater?

That distinction can change the appropriate battery specification.

Compare Watt-Hours, Not Amp-Hours Alone

Amp-hours are useful only when voltage is also known.

Battery energy is calculated as:

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

A 20 Ah battery at one voltage does not contain the same amount of energy as a 20 Ah battery at another voltage. For energy and runtime comparisons, Wh is therefore more informative than Ah by itself.

Even Wh should not be treated as a direct runtime guarantee. Two ROVs can carry the same stored energy but consume it at different rates because of differences in thruster efficiency, drag, payload, lighting and vehicle control.

For an OEM specifying an underwater drone battery, stored energy and expected load therefore have to be assessed together.

How MANLY Battery Can Support Custom Underwater Drone Battery Projects

For an OEM underwater drone project, selecting a battery should begin with the vehicle’s electrical and mission requirements rather than choosing the largest available Ah figure.

MANLY Battery develops customised LiFePO4 and other lithium battery packs for robotic applications, with configurable voltage, capacity, dimensions, BMS parameters, connectors and communication interfaces. The existing robot battery range provides practical electrical platforms from which an application-specific design can be engineered.

MANLY 24V 30Ah Robot Battery Platform
25.6 V nominal | 30 Ah | 768 Wh | 30 A continuous discharge | 60 A peak for 1–3 seconds | optional RS485, RS232 or CAN Bus

The 24V 30Ah platform demonstrates the type of electrical configuration MANLY can build around a robotic system. Voltage, capacity, current, dimensions, housing, connector and BMS requirements can be customised for an OEM programme.

For underwater use, the vehicle designer still needs to engineer and validate the complete battery installation, pressure enclosure, penetrators, sealing and thermal arrangement for the intended operating depth. An enclosure IP rating is not the same thing as a subsea pressure-depth rating; IEC 60529 covers ingress-protection classifications for electrical enclosures, while a deep-water vehicle must also withstand the hydrostatic pressure associated with its operating depth.

Start With Mission Energy, Not Battery Capacity Alone

The first question for a battery manufacturer should be: how much energy does the complete mission require?

A practical starting calculation is:

Required energy (Wh) = average system power (W) × required operating time (h)

The engineering specification should then account for mission reserve, usable state-of-charge limits, ageing, operating temperature and return or recovery requirements.

This approach is more useful than asking for “a 30 Ah underwater drone battery”, because Ah does not describe total energy until the system voltage is known.

For a survey AUV, the calculation might be dominated by propulsion, navigation and sensor operation over a long period. A working ROV may instead have a shorter mission but large transient loads when accelerating against current or operating tools.

Voltage, Peak Current, BMS and Pack Size

Stored energy is only the beginning of the battery specification.

Thrusters can create high short-duration current demand, particularly during acceleration, station keeping or manoeuvring in flow. The battery and BMS therefore need to support both expected continuous load and realistic peak current without inappropriate voltage sag or protection trips.

Physical volume matters as well. Every increase in battery size can change vehicle mass, buoyancy, trim and packaging. The battery enclosure also competes for internal volume with control electronics, payload interfaces and sensors.

MANLY’s robot battery platforms support configurable BMS charging and discharge current, physical dimensions, connectors, wiring and communication. Optional RS485, RS232 and CAN Bus interfaces on the 24V 30Ah platform also illustrate how the battery can be integrated into a wider vehicle-control architecture rather than treated as an isolated energy source.

For OEM development, that is where working directly with a battery manufacturer becomes useful: the pack can be specified around the electrical and mechanical envelope of the vehicle instead of forcing the vehicle to accommodate an unrelated off-the-shelf format.

Design the Battery Around the Vehicle and Pressure System

A successful subsea battery installation is a system-level design.

The lithium battery has to fit the pressure architecture, electrical distribution and buoyancy plan of the ROV or AUV. Engineers also need to consider connector routing, pressure penetrators, service access, charging strategy and how the pack will be isolated if a fault occurs.

Battery design should therefore start alongside the vehicle rather than after the hull has been finalised.

The Lobster Robotics project provides a useful real-world example of this approach. Its battery supplier worked within an existing vehicle envelope and increased available battery life by approximately 60%, while retaining a compact installation and field-service requirements. That is an example of information gained through pack-level optimisation rather than simply enlarging the vehicle.

Why Real-World Runtime Is Often Shorter Than the Headline Figure

Real underwater drone battery life changes because an ROV does not consume a fixed amount of power throughout a mission.

Vehicle speed, current, buoyancy, trim and payload all change how hard the propulsion system must work. Accessories then add another layer of demand.

Thrusters, Speed and Water Current

Thrusters are one of the most variable electrical loads on a battery-powered ROV.

A vehicle holding position in moving water has to produce continuous thrust simply to remain stationary. The same ROV hovering in calm water may need much less propulsion power.

High-speed manoeuvring has a similar effect. Blue Robotics explicitly advises smooth driving at low gain where practical to maximise BlueROV2 battery life. The company’s operating guidance also notes that an ROV that is poorly balanced or not close to neutral buoyancy must work harder to stabilise and maintain depth, reducing runtime.

Battery sizing should therefore be based on expected water conditions rather than laboratory still-water endurance alone.

Lights, Sonar, Grippers and Other Payloads

A working ROV is more than its thrusters.

High-output lights, sonar, cameras, manipulator arms, acoustic equipment, positioning systems, computers and scientific sensors all draw power. Some loads may be relatively constant, while others operate intermittently.

Payload also affects the vehicle mechanically. Added equipment can alter drag, buoyancy and trim, which may increase propulsion demand even before its own electrical consumption is counted.

For this reason, an underwater drone battery designed for a basic camera platform may require a different capacity or discharge specification once the same vehicle becomes an inspection platform carrying sonar and tools.

Temperature, Battery Age and Mission Reserve

Nameplate capacity does not remain the only relevant number throughout a battery’s life.

Lithium battery performance changes with temperature and state of health, while ageing progressively reduces usable capacity and power capability. Modern research continues to identify temperature, charge and discharge rate, depth of discharge and state of charge among the factors that influence lithium-ion ageing.

A professional mission plan should therefore avoid assuming that every deployment can use 100% of a new battery’s nominal energy.

Reserve energy is particularly important underwater. The ROV still needs enough power to return to the recovery point or maintain control while the operator retrieves it.

Battery Capacity, Swapping and Surface Power: How to Compare Systems Properly

The most useful power comparison is not always “which battery lasts longest?”

For professional ROV work, total operational availability may be more important than one uninterrupted dive. That introduces three different strategies: more onboard energy, rapid battery replacement and continuous surface power.

Watt-Hours Give a Fairer Energy Comparison

Wh allows batteries at different voltages and capacities to be compared on stored energy.

For example, stating that one battery has 30 Ah while another has 15 Ah tells little by itself. The voltage must also be known before their stored energy can be compared.

The same Wh figure still cannot predict identical runtime across different ROVs, because energy consumption depends on the vehicle.

A useful comparison therefore combines:

• battery energy in Wh;
• realistic average system load;
• peak discharge requirement;
• published runtime and test conditions;
• payload configuration;
• battery replacement time;
• mission reserve.

That produces a much clearer picture than Ah or maximum runtime alone.

Swappable Batteries Can Matter More Than Maximum Runtime

Imagine an inspection team conducting several short dives around a ship, quay or submerged structure.

In that situation, a field-swappable underwater drone battery may keep operations moving by allowing a depleted pack to charge while another pack is in service. BlueROV2, Blueye and FIFISH E-GO all demonstrate versions of this approach, although the exact replacement process differs between platforms.

For OEMs, this leads to an important design question early in development:

Should the vehicle carry the maximum possible energy, or should it carry a smaller serviceable battery that can be replaced quickly?

A larger pack can extend each deployment, but the complete design must also account for mass, packaging and buoyancy.

When Surface Power Makes More Sense

Some operations need endurance that is difficult to achieve economically with onboard batteries alone.

Blue Robotics offers surface power as an alternative configuration for BlueROV2, allowing continuous operation rather than relying on repeated battery cycles.

Surface power can be attractive for long static inspections, fixed-position observation or repeated work close to a support vessel. It also changes the electrical architecture substantially: power transmission voltage, tether losses, topside supply, conversion hardware and safety all become part of the design.

Real ROV builders raise exactly this problem. Discussions in the ROV community frequently centre on whether to transmit power through the tether, trickle-charge an onboard pack or simply replace batteries between dives. These conversations highlight voltage drop, conductor size, tether weight and propulsion current as practical concerns.

There is therefore no single correct power architecture for every underwater drone.

Matching Battery Runtime to the Underwater Mission

The right underwater drone battery is the one that supports the required mission with an appropriate operating reserve, not necessarily the battery with the largest capacity.

Recreational Filming and Short Surveys

For recreational exploration, filming and short visual surveys, portability can matter as much as endurance.

Compact ROVs such as CHASING DORY demonstrate that around an hour may be sufficient for short dives, while GLADIUS MINI S provides a longer operating window for users who expect extended exploration or repeated filming during a session.

A larger battery is not automatically desirable if it adds unnecessary weight and volume to a highly portable vehicle.

Inspection, Search and Tool-Based Operations

Professional inspection creates a different load profile.

An ROV may need to transit to the work area, hold position against current, illuminate a dark structure, operate sonar, record imagery and use a manipulator before returning for recovery.

In this environment, battery selection should be based on the complete duty cycle. Fast battery replacement may also be important if several assets or locations need to be inspected in one working day.

FIFISH E-GO’s dual-battery system, Blueye’s field-swappable packs and BlueROV2’s rapid battery changes illustrate why serviceability becomes part of endurance rather than a separate issue.

For a custom project, an experienced battery manufacturer can use the expected mission profile to define usable energy, current capability, BMS behaviour and physical pack format.

Long-Endurance Autonomous Missions

AUVs introduce a different optimisation problem.

Because the vehicle operates autonomously and may travel significant distances before recovery, energy density directly affects how much survey work can be completed per launch. Payload power and propulsion efficiency become central design variables.

KONGSBERG’s HUGIN specification of up to 100 hours at four knots demonstrates the scale of endurance achievable in a purpose-built autonomous survey platform.

The Lobster Robotics project provides the complementary battery-design lesson: increasing energy within approximately the same vehicle envelope enabled substantially more survey time without simply enlarging the drone.

For this type of platform, the battery is part of the mission architecture from the start.

Underwater Drone Battery FAQs

Can You Increase an Underwater Drone’s Runtime With a Larger Battery?

Yes, if the vehicle’s electrical and mechanical design can support it. More usable Wh normally provides more potential runtime, but battery voltage, discharge current, mass, dimensions, buoyancy, trim, BMS compatibility and enclosure space also have to match the ROV. A larger underwater drone battery can even increase propulsion demand if additional mass or poor trim makes the vehicle work harder. For OEM projects, battery capacity should therefore be changed as part of the complete vehicle design rather than as an isolated specification.

Can an Underwater Drone Run Continuously From Surface Power?

Some ROVs can. BlueROV2, for example, can be configured with a surface power system for continuous operation instead of relying solely on an onboard battery. Surface power is not a universal retrofit, however. The tether, transmission voltage, conductor size, voltage drop, onboard conversion electronics and electrical safety all need to be engineered together. Battery-powered systems remain attractive where portability, rapid deployment and independence from a topside power supply are priorities.

Can You Take an Underwater Drone Battery on a Plane in the UK?

It depends mainly on the lithium battery’s watt-hour rating and whether it is installed or carried as a spare. UK Civil Aviation Authority guidance states that spare lithium-ion batteries up to 100 Wh can generally be carried without operator approval, while batteries above 100 Wh and up to 160 Wh require operator approval. Applicable spare batteries must be carried in cabin baggage and protected against short circuits. Batteries must also be of a type meeting the relevant UN 38.3 tests. Always confirm the airline’s current rules before travel.

Is LiFePO4 Suitable for an Underwater Drone Battery?

LiFePO4 can be suitable where its voltage characteristics, power capability, mass and pack dimensions match the vehicle, but chemistry should be selected at system level. Different underwater platforms use different lithium technologies. Blue Robotics, for example, supports lithium-ion and lithium-polymer battery configurations, while MANLY’s 24V 30Ah robot platform uses LiFePO4. For a custom ROV or AUV, the battery manufacturer should assess energy density, discharge requirements, packaging, BMS design and mission duration together.

How Much Battery Capacity Does an Underwater Drone Need?

Start with energy, not Ah alone. Estimate the vehicle’s average power consumption in watts and multiply it by the required mission duration in hours to establish a base Wh requirement. Then account for recovery reserve, expected peak loads, ageing, temperature and the usable state-of-charge range. Thrusters, sonar, lighting and manipulators should be included in the load profile. This process produces a useful underwater drone battery specification instead of choosing capacity from a headline runtime target.

Conclusión

Underwater drone battery life cannot be reduced to a single “typical” number. Compact recreational ROVs may operate for around an hour, many professional battery-powered ROVs provide several hours of useful operation, and purpose-built AUVs can extend endurance into tens of hours.

The more useful comparison is how the complete power system supports the mission. Wh indicates stored energy, but currents, thruster load, water conditions, payloads, battery swapping and surface power determine how that energy translates into real underwater work.

For OEM ROV and AUV programmes, this makes early battery integration particularly important. MANLY Battery can configure lithium battery packs around required voltage, capacity, BMS current, communication, connector and mechanical requirements, giving developers a practical route from a mission-energy target to an application-specific battery design.

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