Underwater Robot is an unmanned system designed to navigate, inspect, monitor or perform tasks below the water's surface. These systems range from compact diving devices and underwater thrusters to remotely operated underwater vehicles and long-endurance autonomous underwater vehicles. The battery may power thrusters, cameras, sonar, sensors, communication systems, robotic arms and onboard computers. Each application has a different mission duration, peak power demand, installation space and operating environment. Standard battery packs may not provide the right balance of runtime, output, size and system integration. Grepow develops custom battery cells and battery packs for underwater robotics, including high-energy semi-solid-state batteries, high-rate LiPo batteries, compact LiHV cells and LiFePO₄ solutions.
Battery Solutions for Different Underwater Robotic Systems
| Application | Primary Missions | Key Battery Requirements |
|---|---|---|
| AUVs | Mapping, inspection, scientific research, and long-range navigation | High energy density, lightweight design, and extended runtime |
| Battery-Powered ROVs | Underwater observation, imaging, inspection, and light-duty intervention | High-rate discharge, stable voltage, and strong peak-power output |
| Underwater Thrusters | Underwater propulsion, diver assistance, and intelligent propulsion systems | High discharge capability, low internal resistance, and reliable low-temperature output |
| Resident Subsea Robots | Long-term subsea deployment, autonomous return, and underwater charging | Low-power BMS, service-life management, and redundant power design |
| Underwater Sensors and Diving Devices | Communication, positioning, monitoring, and diving electronics | Compact size, custom-shaped pouch cells, and low self-discharge |
What Makes Underwater Robot Battery Selection More Challenging?
● Limited Space Inside Cylindrical Housings
AUVs and other underwater robots often use cylindrical pressure housings. The battery must provide sufficient capacity while fitting within the available internal diameter and length, leaving room for control boards, wiring, and buoyancy components.
● Long Missions Without Easy Recharging
Once deployed, an AUV cannot replace or recharge its battery as easily as a land-based robot. Mission runtime, return or surfacing reserve, and low-battery response strategies are often more important than nominal capacity alone.
● High Current from Thrusters and Tools
Thruster startup, robotic arm movement, and rapid attitude adjustments can generate large transient current peaks. These loads may cause voltage sag, trigger BMS protection, or restart the vehicle’s control system if the battery is not properly designed.
● Heat Accumulation in Sealed Compartments
Cold seawater does not automatically provide effective battery cooling. When a battery is installed inside a sealed compartment, heat must pass through the mounting structure, enclosure, and thermal interface materials before reaching the surrounding water.
● Low Temperatures and Pressure Changes
Deep-water environments may expose the battery to low temperatures. The complete system may also experience repeated pressure cycles as the vehicle descends, operates, and returns to the surface.
● Difficult Recovery After a Battery Failure
If an underwater robot loses power, it may be unable to surface, return to its recovery point, or maintain communication. Reliable remaining-energy estimation, fault isolation, and emergency power reserves are therefore essential.
Choose the Right Battery Chemistry for the Mission
| Battery Solution | Core Advantages | Best-Suited Underwater Applications | Main Trade-Offs |
|---|---|---|---|
| Semi-Solid-State | High energy density, lower battery weight, and longer mission time | AUVs, long-endurance underwater robots, and air-water hybrid vehicles | Cost and discharge-rate requirements must be evaluated for each project |
| High-Rate LiPo | High continuous and peak current with low internal resistance | ROVs, thrusters, robotic arms, and underwater tools | Requires appropriate thermal management and protection |
| LiHV | More energy and a higher voltage platform within the same available space | Compact underwater robots, communication devices, and portable diving equipment | Requires a charging system compatible with a 4.35V charge voltage |
| LiFePO₄ | Good thermal stability, service life, and safety characteristics | Commercial ROVs, monitoring systems, and subsea backup power | Higher weight and lower energy density than high-energy lithium chemistries |
Why Choose Grepow for Underwater Robot Battery Development?
● High-Energy Semi-Solid-State Technology
Grepow semi-solid-state batteries are suitable for AUVs and long-endurance underwater robots where battery weight, mission duration, and available installation space are critical design constraints.
● High-Rate Pouch Cell Expertise
Grepow applies its experience in UAV and high-power battery development to underwater thrusters, robotic arms, and subsea tools that require stable voltage under high continuous and peak loads.
● Flexible Pouch Cell Form Factors
Pouch cell dimensions and battery layouts can be customized for cylindrical pressure housings, long and narrow compartments, curved internal spaces, and compact underwater devices.
● Multiple Chemistry Options
Instead of applying one chemistry to every project, Grepow can evaluate semi-solid-state, high-rate LiPo, LiHV, and LiFePO₄ solutions according to mission duration, power demand, space, weight, and safety requirements.
● Cell-to-Pack Engineering Support
Grepow supports underwater robotics projects from cell selection through pack integration, including PCM/BMS development, wiring, NTCs, connectors, sample production, and volume manufacturing.
Testing and Compliance Support
Testing and compliance requirements vary according to the battery configuration, target market, operating environment, and underwater system architecture. Grepow can support relevant battery testing, documentation, and project-specific validation based on the application requirements.
Battery Safety and Reliability
● Electrical safety testing
● Overcharge and over-discharge testing
● Short-circuit and overcurrent testing
● Temperature testing
● Vibration and mechanical testing
● Cell and battery pack consistency evaluation
Transportation and Market Compliance
● UN 38.3 transport documentation
● IEC- and UL-related battery safety evaluation
● RoHS and REACH compliance support
● SDS/MSDS and shipping documentation
● Regional compliance support for target markets
Note: Available tests, certifications, and compliance documents depend on the selected battery configuration, target market, and project requirements.
Semi-Solid-State Batteries for Long-Endurance AUV
High-Rate LiPo Batteries for ROV and Thruster
Custom Battery Solution for Underwater Robotics
Grepow semi-solid-state batter
ies are designed for underwater systems that need more energy without significantly increasing battery weight. They are suitable for autonomous underwater vehicles used in surveying, inspection, research, and long-range missions.
Key advantages:
● High gravimetric energy density
● Reduced battery weight
● Longer mission range
● Large-capacity pouch cell options
● Custom 22–24V and 44–52V configurations
● Low-temperature options
● Smart battery management
Battery Model | Capacity/Energy | Rated Voltage | Land-off Voltage | Dimension | Weight | Energy Density | Constant Discharge | Peak Current |
TARBG3812K04S10X | 12Ah 177.6Wh | 4S 14.8V | 11.44V | 22.0*71.5*190mm | 580g | 306.21Wh/kg | 36A | 120A |
TARBG3836K06S10X | 36Ah 799.2Wh | 6S 22.2V | 17.16V | 59*89*206.5mm | 2250g | 350.27Wh/kg | 108A | 360A |
TARBG3599K06S10X | 99Ah 2197.8Wh | 6S 22.2V | 17.28V | 72.2×151.5×287mm | 6829.79g | 321.80Wh/kg | 297A | 495A(≤3S) |
TARBG3887K08S10X | 87Ah 2575.2Wh | 8S 29.6V | 22.88V | 79*151.5*287mm | 7040g | 365.80Wh/kg | 261A | 870A |
TARBG3836K12S10X | 36Ah 1598.4Wh | 12S 44.4V | 34.32V | 127*89*209.5mm | 4600g | 342.65Wh/kg | 108A | 360A |
TARBG3887K14S10X | 87Ah 4506.6Wh | 14S 51.8V | 40.04V | 150*151.5*292mm | 13300g | 338.84Wh/kg | 261A | 870A |
High-discharge-rate LiPo batteries are suitable for a remotely operated vehicle, underwater thruster, or robotic tool that experiences rapid changes in power demand.
Key advantages:
● High continuous-current capability
● Strong peak-current output
● Low internal resistance
● Reduced voltage sag
● Stable output during thruster startup
● Flexible voltage and capacity configurations
Model | Capacity | Nominal Voltage | Energy | Discharge Rate | Weight | Dimension |
TAA37004S45X6 | 3700mAh | 4S1P 14.8V | 54.76Wh | 45C | 361g | 136×44×29mm |
TAA52004S35X6 | 5200mAh | 4S1P 14.8V | 76.96Wh | 35C | 436.5g | 133×45×33.5mm |
TAA10K4S30E5 | 10000mAh | 4S1P 14.8V | 148Wh | 30C | 935g | 177×66×39mm |
TAA100006S30AX | 10000mAh | 6S1P 22.2V | 222Wh | 30C | 1360g | 177×66×58mm |
TAA120006S30E | 12000mAh | 6S1P 22.2V | 266.4Wh | 30C | 1532g | 192×72×54mm |
TAA160006S30X | 16000mAh | 6S1P 22.2V | 355.2Wh | 30C | 1974g | 190×76×65mm |
TAA22000BS30X | 22000mAh | 6S1P 22.2V | 488.4Wh | 30C | 2460g | 206×91×61mm |
TAA28K6S25ASX | 28000mAh | 6S1P 22.2V | 621.6Wh | 25C | 3413g | 205×121×67mm |
TARBAS30K0625X | 30000mAh | 6S1P 22.2V | 666Wh | 25C | 3494g | 216×125×61mm |
For underwater projects that cannot be supported by standard batteries, Grepow can customize pouch cells and complete battery packs according to the available space, voltage platform, capacity, power demand, and operating environment. Available options include low-temperature batteries for cold-water missions, high-energy-density batteries for extended endurance, high-discharge-rate batteries for thrusters and robotic tools, and LiFePO₄ batteries for applications requiring enhanced safety and long service life. Battery pack customization can also include the BMS, wiring, connectors, communication functions, mechanical structure, and thermal management design.
