AGV & AMR BATTERY SIZING GUIDE
Sizing a battery pack for an automated guided vehicle or autonomous mobile
robot requires more than choosing a voltage and amp-hour rating. The battery must supply enough energy for the required operating time, support motor startup and acceleration current, communicate with the robot controller and recharge safely within the available charging window.
An AGV or AMR battery pack is a rechargeable power system designed around the robot's electrical platform, duty cycle, load profile, charging strategy, installation space and operating environment. A reliable design starts with the robot's real power data rather than selecting a battery from capacity alone.
Five Parameters That Determine AGV or AMR Battery Size
01. Voltage: Match the motor controller, onboard electronics and charger.
02. Energy: Calculate watt-hours from average power and required runtime.
03. Current: Confirm continuous, startup and short-duration peak current.
04. BMS: Define protection, balancing, monitoring and communication functions.
05. Charging: Match the battery to manual, removable or automatic dock charging.
1. Define the AGV or AMR Duty Cycle Before Sizing the Battery
Battery sizing should begin with a complete operating cycle. Two robots with the same motor voltage may need very different battery packs because one moves
continuously while the other waits, lifts loads, accelerates frequently or returns to a charging station between tasks.
Record the power consumption of the drive motors, controller, navigation sensors, cameras, industrial computer, wireless communication system, lifting
mechanism and other auxiliary equipment. Where measured data is available, use average consumption from a representative work shift instead of adding every component's maximum rating.
Information Required Before Battery Sizing
Robot type, payload and operating route
Motor and controller nominal voltage
Average power during normal operation
Continuous, startup and peak current
Required runtime between charging periods
Idle time and opportunity-charging windows
Maximum battery dimensions and allowable weight
Temperature, vibration, dust and moisture conditions
A warehouse AMR that carries light goods on a flat floor has a different load profile from an AGV that repeatedly starts, climbs an incline or lifts a heavy
pallet. The battery specification should reflect these actual operating conditions.
2. Match Battery Voltage to the Robot Electrical Platform
The nominal pack voltage must be compatible with the motor controller, onboard electronics and charging system. AGVs and AMRs may use 24V, 36V,
48V or other system voltages, while compact cleaning and service robots may operate at lower voltage levels.
Nominal voltage is only one part of the requirement. The battery supplier also needs to know the maximum permitted voltage when the pack is fully charged and
the minimum voltage at which the robot controller stops operating. These limits affect cell chemistry, the number of cells in series and BMS settings.
Voltage Parameters to Confirm
Nominal voltage: Normal operating voltage of the robot platform
Maximum voltage: Highest voltage accepted by the controller
Minimum voltage: Robot undervoltage or shutdown threshold
Charge voltage: Required charger output voltage
Auxiliary range: Voltage limits of DC-DC converters and sensors
Engineering Note:
Do not replace an existing battery only because the new pack has a similar nominal voltage. Different lithium chemistries may have different full-charge and discharge voltage ranges.
3. Calculate Battery Energy, Runtime and Required Capacity
Runtime should first be calculated in watt-hours rather than amp-hours. Watt-hours describe the total available energy and allow batteries at different voltages to be compared more accurately.
BASIC ENERGY FORMULA
Battery Energy (Wh) = Average Robot Power (W) × Runtime (h)
The base result should be adjusted for usable discharge capacity, power-conversion losses, temperature, battery aging and operational reserve.
PRACTICAL SIZING FORMULA
Required Nominal Energy = Base Energy ÷ Usable Capacity Fraction ÷ System Efficiency
Example: Sizing a Battery for a 48V AGV
Assume an AGV consumes an average of 420W and must operate for six hours before charging.
| Average Robot Power | 420W |
| Required Runtime | 6 hours |
| Base Energy | 420W × 6h = 2,520Wh |
| Usable Capacity Window | 80% |
| Estimated Efficiency | 90% |
| Required Nominal Energy | 2,520 ÷ 0.80 ÷ 0.90 = 3,500Wh |
Preliminary 48V Capacity:
3,500Wh ÷ 48V ≈ 72.9Ah
This result is a starting point. The pack must still be checked against discharge current, temperature, available space, weight, charging time and expected capacity loss over its service life.
4. Size Continuous, Startup and Peak Discharge Current
A battery that provides enough watt-hours can still fail if it cannot deliver the required current. Drive motors may draw much more current during startup,
acceleration, turning, lifting or climbing than during steady-speed travel.
CURRENT ESTIMATE
Current (A) = Power (W) ÷ Battery Voltage (V)
A 48V robot requiring 2,400W during acceleration draws approximately 50A before conversion losses and auxiliary loads are included. The cells, BMS,
busbars, fuse, cables and connector must all support the required current.
| Current Type | Meaning | Design Impact |
|---|
| Average Current | Typical current over a complete duty cycle | Used for runtime and energy calculations |
| Continuous Current | Current supplied for an extended period | Determines thermal and BMS continuous rating |
| Peak Current | Short high-current demand during acceleration or lifting | Determines voltage-drop and shutdown risk |
Important: Peak-current duration and repetition frequency must be supplied. A 100A peak lasting one second creates a different thermal load from 100A lasting two minutes.
5. Specify the BMS, Communication and Dock-Charging System
BMS Protection and Robot Communication
An AGV or AMR battery management system should be selected according to the cell configuration, voltage range, current profile and robot-control
requirements.
Typical BMS Functions
Cell-voltage and pack-voltage monitoring
Overcharge and over-discharge protection
Continuous and peak overcurrent protection
Short-circuit and temperature protection
Cell balancing
State-of-charge and state-of-health reporting
Fault-code and remaining-runtime reporting
Depending on the robot controller, communication may use CAN, RS485, UART or a project-specific protocol. The message definitions, data rate, connector
and fault-handling logic should be agreed before prototype production.
Automatic Dock Charging
Dock charging affects battery size and fleet utilization. A robot that
recharges during short idle periods may use a smaller battery than a robot
that must operate an entire shift before charging.
| Dock-Charging Item | Requirement to Confirm |
|---|
| Charging Window | Available charging time between missions |
| Charger Output | Voltage, current and charging profile |
| Charging Contact | Position, alignment tolerance and polarity |
| Communication | Charger enable signal and communication handshake |
| Temperature Control | Cell and pack temperature limits during charging |
6. AGV and AMR Battery Sizing Checklist
| Design Item | Information to Confirm | Why It Matters |
|---|
| Voltage | Nominal, maximum and minimum voltage | Determines chemistry and controller compatibility |
| Runtime | Average power and operating hours | Determines watt-hours and amp-hours |
| Current | Continuous and peak current | Determines cell and BMS ratings |
| Charging | Manual, removable or dock charging | Affects charge rate and fleet availability |
| Communication | CAN, RS485, UART or custom protocol | Supports monitoring and system coordination |
| Mechanical Design | Dimensions, weight and mounting | Ensures secure installation |
Related Robot Battery Solutions
Conclusion
Correct AGV and AMR battery sizing begins with the robot's real duty cycle. Match the complete voltage range, calculate energy in watt-hours, verify continuous and peak current, define BMS communication and evaluate the charging station together with the battery. A pack that balances runtime,
current capability, charging time, size and service-life requirements is more useful than one selected from amp-hours alone.
AGV & AMR BATTERY FAQ
Frequently Asked Questions
How many amp-hours does an AGV battery need?
Calculate required watt-hours from average power and runtime, adjust for usable capacity and system efficiency, and then divide by nominal voltage.
Should an AGV battery be sized from average or maximum power?
Average power determines energy and runtime. Maximum power determines cell, BMS, cable and connector current ratings. Both values are required.
Can an AGV use opportunity charging?
Yes. Opportunity charging may occur during loading, unloading or planned idle periods, provided the cells, BMS and charger support the required rate.
Does an AMR battery need CAN communication?
Not every system requires CAN. Some robots use RS485, UART or basic status signals depending on the controller and fleet-management system.
What information should be sent to a battery manufacturer?
Provide system voltage, average power, continuous and peak current, runtime, dimensions, charging method, temperature, communication protocol
and estimated production quantity.
CUSTOM AGV & AMR BATTERY PROJECT
Planning an AGV or AMR Battery Pack?
Send Yilai the robot voltage, average power, peak current, required runtime, installation dimensions and charging method for an initial battery
feasibility evaluation.
Discuss Your AGV or AMR Battery Requirements 
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