Autonomous Mobile Robot Battery Guide for Outdoor and Agricultural AMRs

Autonomous mobile robots (AMRs) are moving beyond warehouses and factories into orchards, vineyards, greenhouses, farms, parks, and other outdoor environments. These robots perform tasks such as crop monitoring, transportation, mowing, spraying, inspection, towing, and material handling with limited human intervention.

Compared with indoor AMRs, outdoor and agricultural robots face a wider range of operating conditions. Uneven terrain, slopes, mud, dust, rain, vibration, temperature changes, variable payloads, and long operating cycles can all affect battery performance.

For robot manufacturers, the battery is therefore more than an energy-storage component. It is part of the robot’s complete power system, working together with the motors, motor controller, charger, BMS, sensors, communication system, and onboard computer.

This guide explains how to evaluate and design lithium battery packs for outdoor and agricultural autonomous mobile robots.

1. What Is an Agricultural Autonomous Mobile Robot?

An agricultural AMR is a mobile robotic platform designed to navigate and perform tasks with limited manual operation.

Zu den üblichen Anwendungen gehören:

• Crop inspection
• Orchard monitoring
• Vineyard monitoring
• Autonomous mowing
• Weed control
• Agricultural spraying
• Crop transportation
• Harvest assistance
• Greenhouse logistics
• Field inspection
• Soil monitoring
• Autonomous towing

Depending on the application, an AMR may include drive motors, steering systems, cameras, LiDAR, GNSS or RTK positioning, wireless communication, onboard computers, pumps, actuators, and other powered equipment.

Each subsystem consumes energy.

Battery selection should therefore be based on the complete robot duty cycle, rather than the motor’s nominal power alone.

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2. What Must an Outdoor AMR Battery Handle?

Outdoor agricultural robots operate in conditions that can change during a single mission.

A robot may travel across:

• Concrete
• Grass
• Soil
• Gravel
• Schlamm
• Slopes
• Uneven farmland
• Wet surfaces

The battery may also be exposed to:

• Regen
• Staub
• Water spray
• Hohe Temperaturen
• Niedrige Temperaturen
• Vibration
• Mechanical shock

These factors influence both the electrical and mechanical requirements of the battery pack.

Variable loads

An agricultural AMR does not normally consume a constant amount of power.

Power demand can increase during:

• Beschleunigung
• Hill climbing
• Drehen
• Driving through soft soil
• Carrying heavy payloads
• Towing
• Starting pumps
• Operating mowing or spraying equipment

The battery therefore needs sufficient energy capacity as well as sufficient continuous and peak discharge capability.

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3. How to Calculate AMR Battery Capacity

The first step in battery sizing is to determine the robot’s energy requirement.

The basic equation is:

Energie (Wh) = Spannung (V) × Kapazität (Ah)

Zum Beispiel:

A 51.2 V 100 Ah LiFePO4 battery provides approximately:

51.2 V × 100 Ah = 5,120 Wh

or approximately 5.12 kWh of nominal energy.

However, nominal energy is not the same as the energy available for every mission.

Actual usable energy depends on:

• Operating SOC range
• Batterietemperatur
• Entladungsstrom
• BMS-Einstellungen
• Batteriealterung
• Systemeffizienz
• Terrain
• Nutzlast
• Robot operating strategy

Example battery calculation

Suppose an agricultural AMR consumes an average of 600 W and needs to operate for 8 hours.

Energiebedarf:

600 W × 8 h = 4,800 Wh

The engineering team should then add an appropriate operating reserve based on actual field conditions and the required mission reliability.

The final battery capacity should be validated through prototype and field testing rather than relying only on theoretical calculations.

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4. Average Power vs. Peak Power

Battery selection should distinguish between average power und peak power.

Average power

Average power determines how much energy the robot consumes during a typical mission.

It is affected by:

• Driving speed
• Route length
• Nutzlast
• Terrain
• Motoreffizienz
• Sensoren
• Computing
• Auxiliary equipment

Peak power

Peak power determines whether the battery can handle short periods of high demand.

Examples include:

• Motor startup
• Rapid acceleration
• Steep slopes
• Heavy towing
• Soft soil
• Pump startup
• Agricultural implements

A battery may have enough watt-hours for the required runtime but still be unsuitable if its BMS or cells cannot support the robot’s peak current.

For this reason, both energy capacity and discharge current should be specified during battery development.

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5. Choosing the Battery Voltage

Common voltage platforms for mobile robots include:

• 24 V
• 36 V
• 48 V
• 51.2 V
• 60 V
• 72 V

The correct voltage depends on the robot’s electrical architecture.

The battery must be compatible with:

• Antriebsmotoren
• Motor controllers
• DC/DC converters
• Ladegeräte
• BMS
• Actuators
• Auxiliary systems

The relationship between power, voltage, and current is:

P = V × I

For a given power requirement, a higher system voltage can reduce current. However, the battery voltage should always be determined together with the complete electrical system.

For an existing robot platform, the battery should match the specified voltage range rather than changing the system voltage simply to increase battery capacity.

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6. Why LiFePO4 Is Used for Agricultural Robot Batteries

LiFePO4, or lithium iron phosphate, is widely used in industrial mobile equipment and robotic applications.

For agricultural AMRs, the chemistry can be suitable when the project requires:

• Repeated charging and discharging
• Stabiler Betrieb
• Thermische Stabilität
• Industrial-duty operation
• Large battery capacity

LiFePO4 batteries are available in cylindrical, prismatic, and other cell formats.

The appropriate cell format depends on:

• Required capacity
• Entladungsstrom
• Available space
• Mechanical structure
• Gewicht der Batterie
• Production volume
• Thermal requirements

Cell selection should be based on the complete battery specification rather than capacity alone.

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7. BMS Requirements for Autonomous Mobile Robots

The Battery Management System is a core part of an AMR battery pack.

A properly designed BMS can monitor:

• Zellspannung
• Pack-Spannung
• Aktuell
• Cell temperature
• Batterietemperatur
• SOC
• Fehlerstatus

Protection functions may include:

• Schutz vor Überladung
• Schutz vor Überentladung
• Überstromschutz
• Kurzschlussschutz
• Schutz vor Überhitzung
• Under-temperature protection
• Zellausgleich

For autonomous robots, BMS communication is also important.

The robot controller can use battery information to determine whether the robot should:

• Continue its current mission
• Return to a charging station
• Reduce power consumption
• Stop safely
• Begin charging
• Request a battery replacement

The BMS therefore becomes part of the robot’s energy-management system.

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8. CAN Bus and RS485 Communication

Smart battery communication can be useful for agricultural AMRs.

Common interfaces include:

CAN-Bus

CAN is widely used in mobile equipment and vehicle-related systems.

Battery information can include:

• Spannung
• Aktuell
• SOC
• Temperatur
• Fehlerstatus
• Ladezustand

RS485

RS485 is also used in industrial systems and can support communication between the battery, robot controller, charger, or other equipment.

However, having the same physical interface does not guarantee compatibility.

The battery and robot controller should define:

• Baud rate
• Kommunikationsprotokoll
• CAN IDs
• Data format
• Scaling
• Fault codes
• Charging commands
• Communication timeout behavior

Communication should be tested with the actual robot controller before mass production.

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9. IP Protection for Outdoor Agricultural Robot Batteries

Outdoor agricultural batteries may encounter dust, rain, irrigation water, mud, and cleaning processes.

The battery enclosure should therefore be designed according to the actual environmental requirements.

Common IP ratings considered for outdoor battery systems include:

• IP65
• IP67
• IP68

The appropriate rating depends on the installation and operating conditions.

For example, IP67 provides protection against dust ingress and temporary immersion under specified test conditions.

However, the battery enclosure is only one part of the system.

Engineers should also evaluate:

• Steckverbinder
• Cable glands
• Wiring
• Service covers
• Mounting interfaces
• Venting
• Sealing surfaces

A battery case with an IP rating does not automatically make the complete robot waterproof.

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10. Temperature Management

Agricultural robots may operate during different seasons and in different climates.

Battery temperature affects charging, discharging, available power, and battery aging.

High-temperature environments

High ambient temperatures can increase thermal stress.

The battery system should consider:

• Temperatursensoren
• BMS temperature protection
• Wärmeableitung
• Enclosure design
• Charging temperature limits

Cold environments

Low temperatures can reduce available battery performance and require additional charging controls.

Je nach Anwendungsfall sind für den Akku möglicherweise folgende Komponenten erforderlich:

• Low-temperature charging protection
• Heating elements
• Thermal insulation
• BMS-controlled heating
• Überwachung der Temperatur

For agricultural AMRs operating in cold regions, the charging environment should be considered during the initial battery design.

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11. Vibration and Shock Testing

Outdoor AMRs are exposed to repeated mechanical vibration.

Typical sources include:

• Uneven farmland
• Gravel
• Ruts
• Stones
• Slopes
• Sudden braking
• Motor vibration
• Verkehr

Battery pack construction should therefore consider:

• Cell fixation
• Module support
• Busbar structure
• Schweißen
• Connector retention
• Kabelverlegung
• Enclosure strength
• Befestigungspunkte

Testing should ideally reflect the robot’s actual operating environment.

For example, laboratory electrical testing cannot completely reproduce the mechanical loads generated when a robot repeatedly travels across rough agricultural terrain.

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12. Charging Strategies for Agricultural AMRs

Charging strategy has a direct relationship with battery capacity.

Three common approaches are:

Full charging

The robot completes a mission, returns to a charging station, and charges before the next mission.

Opportunitätskosten

The robot charges during operational breaks.

Examples include:

• Between missions
• During shift changes
• While waiting for another task
• During scheduled downtime

Austausch der Batterie

A depleted battery is replaced with a charged battery.

This can be useful when the robot needs extended operating time and the mechanical design supports battery replacement.

The battery, charger, and BMS should be developed as one charging system.

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13. Battery Mechanical Design

Agricultural robots often have strict space and weight limitations.

The battery may need to be installed:

• Under the chassis
• Inside the frame
• Behind the control cabinet
• Beneath the payload platform
• Inside a sealed compartment

Important mechanical parameters include:

• Länge
• Breite
• Höhe
• Gewicht
• Mounting holes
• Anschlussposition
• Cable direction
• Service access

Battery placement also affects the robot’s center of gravity.

A poorly positioned battery can influence:

• Traction
• Stabilität
• Wheel loading
• Ground clearance
• Turning performance

For this reason, battery mechanical design should ideally begin together with the robot chassis design.

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14. Outdoor AMR Battery Safety

A complete battery safety design can include several protection layers.

Cell level

• Überwachung der Zellspannung
• Überwachung der Temperatur
• Zellausgleich

BMS level

• Schutz vor Überladung
• Schutz vor Überentladung
• Überstromschutz
• Kurzschlussschutz
• Temperaturschutz

Pack level

• Fuse
• Contactor or MOSFET protection
• Pre-charge circuit when required
• Insulation
• Mechanical protection

System level

• Charger communication
• Motor controller coordination
• Emergency shutdown
• Fault reporting

Battery safety should be validated according to the actual product design and applicable standards.

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15. Battery Testing for Agricultural AMRs

A battery designed for an outdoor robot should undergo electrical, environmental, and mechanical validation.

Elektrische Prüfungen

Typical tests include:

• Prüfung der Kapazität
• Charge testing
• Discharge testing
• Continuous-current testing
• Peak-current testing
• BMS protection testing
• Kommunikationstests

Environmental testing

Depending on the application:

• Prüfung bei hohen Temperaturen
• Prüfung bei niedrigen Temperaturen
• Temperature cycling
• Humidity testing
• Water ingress testing
• Dust exposure

Mechanische Prüfung

Possible tests include:

• Vibrationsprüfung
• Shock testing
• Drop testing where applicable
• Connector retention
• Enclosure strength

Production testing

Battery production may also include:

• Voltage inspection
• Internal resistance inspection
• Prüfung der BMS-Kommunikation
• Prüfung der Kapazität
• Isolationsprüfung
• Alterungsprüfung
• Funktionsprüfung

Testing requirements should be defined according to the robot’s actual operating conditions.

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16. Battery Certification and Compliance

For AMR manufacturers selling products internationally, battery compliance should be considered during the development stage.

Potential requirements may include:

• UN38.3
• IEC 62133-2
• CE
• RoHS
• EMC-related requirements
• EU Battery Regulation
• Customer-specific requirements

The exact certification path depends on the battery design, destination market, transportation requirements, robot classification, and final application.

For the European market, Regulation (EU) 2023/1542 specifically includes batteries intended for agricultural activities within its broad industrial-battery category.

The regulation also establishes performance and durability information requirements for rechargeable industrial batteries above 2 kWh.

Therefore, European AMR projects should consider battery documentation, performance data, traceability, labeling, and other applicable requirements early in the development process.

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17. How to Choose an AMR Battery Manufacturer

For an OEM/ODM agricultural robot project, the battery supplier should be evaluated beyond the quoted voltage and capacity.

Consider whether the manufacturer can provide:

Kundenspezifisches Batteriedesign

• Spannungsanpassung
• Anpassung der Kapazität
• Abmessungen
• BMS
• Steckverbinder
• Wiring
• Kommunikation
• Enclosure
• Befestigungskonstruktion

Entwicklung von Prototypen

A typical development process can include:

Requirement → Battery Design → Prototype → Robot Integration → Testing → Optimization → Mass Production

Battery traceability

Ask about:

• Cell batch information
• BMS version
• Production records
• Test records
• Serial numbers
• Qualitätsprüfung

Unterstützung bei der Zertifizierung

The supplier should understand the certification and transportation requirements of the target market.

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18. OEM/ODM Battery Solutions for Agricultural AMRs

Agricultural AMRs often require customized battery packs rather than standard batteries.

A custom battery may be designed around:

• Robot voltage
• Required capacity
• Peak current
• Betriebszeit
• Verfügbarer Einbauraum
• Gewichtsbeschränkungen
• Kommunikationsprotokoll
• Ladegerät
• Umgebungsbedingungen

Zum Beispiel:

Battery Chemistry: LiFePO4
Nennspannung: 51.2 V
Capacity: 100 Ah
Energie: 5.12 kWh
BMS: Intelligente BMS
Communication: CAN / RS485
Application: Agricultural AMR
Enclosure: Outdoor-rated
Aufladen: Dedicated charger
Anpassungen: Housing, connector, wiring and mounting

The final specification should be based on measured robot loads and field operating conditions.

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19. Agricultural AMR Battery Specification Checklist

Before contacting a battery manufacturer, prepare the following information:

The more complete the specification, the easier it is for the battery manufacturer to develop a suitable solution.

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20. Final Considerations When Selecting an Outdoor AMR Battery

An agricultural robot battery needs to perform as part of the complete robot system.

The battery should be evaluated according to:

• Energiebedarf
• Peak power
• Continuous current
• Duty cycle
• Chemie der Batterie
• BMS
• Kommunikation
• Aufladen
• Temperatur
• Water and dust exposure
• Vibration
• Mechanical installation
• Zertifizierung
• Production traceability

For many outdoor AMR applications, a LiFePO4 battery pack with a smart BMS, CAN/RS485 communication, appropriate enclosure protection, and customized mechanical design can provide a suitable platform for robot power-system development.

The key is to avoid selecting a battery based only on an Ah number.

The right AMR battery is designed around the robot’s actual mission, terrain, load, charging strategy, and operating environment.