How to Select the Right Battery Pack for Your Equipment

Choosing a lithium battery pack for equipment requires more than selecting a voltage and capacity. The battery needs to work with the equipment’s electrical system, physical structure, operating environment, and charging system.

Different applications also have different requirements. An AGV may need frequent charging and CAN communication, while an electric motorcycle may require high discharge current and weather protection. A medical device may have specific size and safety requirements, while an energy storage system may focus on capacity and cycle performance.

Selecting the right battery pack starts with understanding the complete requirements of the equipment.

This guide explains the main factors to consider when selecting or customizing a lithium battery pack.

1. Understand the Equipment’s Power Requirements

The first step is to understand how much power the equipment requires during normal and peak operation.

Zu den wichtigen Parametern gehören:

• Rated power
• Operating voltage
• Continuous current
• Peak current
• Betriebszeit
• Daily usage frequency

For example, a motor-driven device may require a higher current during startup or acceleration than during normal operation.

A battery pack should therefore be designed based on both continuous and peak power requirements.

Calculate Battery Energy Requirements

Battery energy can be estimated using:

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

For example, a 48V 20Ah battery pack has a nominal energy capacity of approximately:

48 × 20 = 960Wh

The actual operating time depends on equipment power consumption, operating conditions, load, and battery system efficiency.

2. Select the Correct Battery Voltage

Battery voltage must be compatible with the equipment’s electrical system.

Common lithium battery pack voltage ranges include:

• 12V
• 24V
• 36V
• 48V
• 52V
• 60V
• 72V

The battery voltage should be checked against:

• Motor voltage
• Controller voltage
• Equipment input voltage
• Charger output voltage
• BMS-Konfiguration

For example, a lithium battery pack designed for a 48V system may use a 13-series configuration with a full-charge voltage of approximately 54.6V when using standard lithium-ion cells.

The nominal voltage and full-charge voltage should both be considered when confirming system compatibility.

3. Determine the Required Battery Capacity

Capacity is generally measured in ampere-hours (Ah).

A higher capacity battery can provide more stored energy, but it can also increase the battery’s size and weight.

Capacity selection should consider:

• Required operating time
• Equipment power consumption
• Available installation space
• Maximum allowable battery weight
• Ladehäufigkeit

For equipment operating for long periods, a larger battery capacity may be required.

For portable equipment, the design may need to balance capacity with weight and dimensions.

4. Choose the Appropriate Battery Chemistry

Different battery chemistries have different characteristics.

NMC Lithium-ion Batteries

NMC cells are commonly used where energy density and compact battery design are important.

Potential applications include:

• E-Fahrräder
• Elektrische Motorräder
• Scooters
• Tragbare Geräte

LiFePO4 Batteries

LiFePO4 cells are commonly used in applications requiring stable operation and repeated charging and discharging.

Potential applications include:

• AGV
• AMR
• Industrielle Ausrüstung
• Marine systems
• Energiespeicherung

Lithium Polymer Batteries

Lithium polymer cells offer flexible packaging and can be used for products with specific shape or space requirements.

Potential applications include:

• Drohnen
• Portable electronics
• Compact equipment

Battery chemistry should be selected according to the complete application rather than a single performance parameter.

5. Check Continuous and Peak Discharge Current

Battery capacity alone does not determine whether a battery can power equipment correctly.

The battery pack must also provide sufficient current.

Two important parameters are:

• Kontinuierlicher Entladestrom
• Spitzenableitstrom

For example, electric motors may require a short period of high current during startup.

Industrial equipment may require stable continuous current during extended operation.

The BMS discharge rating and battery cell discharge capability should both match the equipment requirements.

6. Consider Battery Size and Installation Space

A battery pack must physically fit inside or onto the equipment.

Before designing the battery, measure:

• Länge
• Breite
• Höhe
• Mounting points
• Anschlussposition
• Cable exit location
• Available clearance

Mechanical requirements can significantly affect battery configuration.

For example, an e-bike battery may need to fit inside a down tube, rear rack, or seat tube.

Industrial equipment may require a custom metal enclosure with specific mounting brackets.

Providing a mechanical drawing or installation space information to the battery manufacturer can help with battery pack design.

7. Select the Appropriate BMS

The Battery Management System (BMS) is an important part of a lithium battery pack.

A BMS may monitor:

• Zellspannung
• Pack voltage
• Ladestrom
• Entladestrom
• Temperatur
• State of charge

Common protection functions include:

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

For equipment requiring battery communication, the BMS may also support:

• CAN
• CAN-FD
• RS485
• UART
• Modbus

The BMS should be selected according to the equipment’s electrical and communication requirements.

8. Consider the Operating Environment

The battery’s operating environment can affect battery design.

Important environmental factors include:

• Ambient temperature
• Luftfeuchtigkeit
• Water exposure
• Staub
• Vibration
• Mechanical shock
• Betrieb im Innen- oder Außenbereich

For outdoor equipment, the battery enclosure may require additional protection against water and dust.

For industrial equipment, vibration resistance and mechanical mounting may require additional consideration.

For cold environments, charging and discharging temperature limits should be evaluated during the design stage.

9. Evaluate Charging Requirements

The battery pack should be compatible with the charging system.

Important charging parameters include:

• Charger output voltage
• Ladestrom
• Ladeverfahren
• Aufladezeit
• Charging temperature range
• Charging connector

The charger and BMS settings should be matched to the battery configuration.

For applications with frequent operation, charging time may also be an important design parameter.

10. Consider Battery Communication Requirements

Some equipment requires the battery to communicate with the main controller.

A smart battery system may provide information such as:

• Ladezustand (SOC)
• Batteriespannung
• Aktuell
• Temperatur
• Fault information
• Verbleibende Kapazität

Communication protocols may include CAN, RS485, UART, or Modbus.

This function is commonly considered for:

• AGV
• AMR
• Roboter
• Industrielle Ausrüstung
• Elektrische Fahrzeuge

Communication requirements should be confirmed before the BMS is selected.

11. Check Safety and Certification Requirements

Battery requirements can vary depending on the destination market and application.

Common standards and certifications may include:

• UN38.3
• IEC 62133-2
• CE
• UL2271
• FCC
• RoHS

Transportation requirements should also be considered when shipping lithium batteries internationally.

For OEM projects, certification requirements should ideally be identified during the product development stage.

This can reduce the risk of changing the battery design after prototype development.

12. Consider Battery Protection and Enclosure Design

The battery enclosure protects the internal cells, BMS, wiring, and other components.

Depending on the application, the enclosure may need to address:

• Dust protection
• Water protection
• Impact protection
• Wärmeableitung
• Mechanical mounting

Common housing materials include:

• Plastic
• Aluminum
• Steel
• Custom composite structures

For outdoor applications, an appropriate IP protection level may be required.

13. Evaluate Cell Consistency and Battery Pack Quality

A battery pack normally contains multiple cells connected in series and parallel.

Cell consistency is therefore important.

Manufacturers may evaluate:

• Zellspannung
• Innerer Widerstand
• Kapazität
• Cell appearance

Cells with suitable consistency can be selected and grouped before battery assembly.

Battery pack production may also include:

• Welding inspection
• BMS testing
• Charging and discharging tests
• Alterungstests
• Final electrical inspection

14. Consider the Expected Service Conditions

Battery selection should take the expected usage pattern into account.

Bedenken Sie Folgendes:

• Tägliche Öffnungszeiten
• Ladehäufigkeit
• Depth of discharge
• Expected service period
• Storage conditions

For example, an AGV operating several shifts per day may have different battery requirements from equipment used only a few hours per week.

The expected usage pattern can influence cell chemistry, capacity, BMS settings, and thermal design.

15. Work With a Battery Manufacturer During Product Development

For a custom battery project, it can be useful to involve the battery manufacturer during the equipment development stage.

A battery manufacturer can support:

• Battery specification design
• Zellauswahl
• Reihen- und Parallelschaltung
• BMS selection
• Tragwerksplanung
• Connector selection
• Prototypenfertigung
• Battery testing
• Certification preparation
• Mass production

Early communication allows electrical and mechanical requirements to be considered together.

16. What Information Should You Provide to a Battery Manufacturer?

When requesting a custom battery solution, providing detailed technical information can make the design process more efficient.

Useful information includes:

If some parameters are not available, equipment power consumption, operating time, and installation dimensions can still provide useful information for preliminary battery design.

17. Common Mistakes When Selecting a Battery Pack

Several issues can occur when battery selection focuses only on voltage and capacity.

Choosing Capacity Without Checking Current

A battery may have sufficient Ah capacity but still be unsuitable if its discharge current is not sufficient for the equipment.

Ignoring Installation Space

A battery with suitable electrical specifications may not fit into the equipment.

Selecting a BMS Without Checking Communication

If the equipment requires CAN or RS485 communication, the BMS needs to support the required protocol.

Considering Certification Too Late

Certification requirements can influence cell selection, BMS design, enclosure design, and testing.

Ignoring the Operating Environment

Temperature, water, dust, vibration, and mechanical shock can all affect battery pack design.

Schlussfolgerung

Selecting the right battery pack requires consideration of both electrical and mechanical requirements.

Key factors include:

• Spannung
• Kapazität
• Continuous and peak current
• Chemie der Batterie
• Zellkonfiguration
• BMS
• Physical dimensions
• Charging requirements
• Betriebsumgebung
• Kommunikationsfunktionen
• Sicherheitsbescheinigungen

For equipment manufacturers, a custom battery pack can be designed around the actual product requirements rather than using a standard battery with fixed specifications.

By providing detailed equipment information to a lithium battery manufacturer, the battery design can be evaluated from the electrical, mechanical, environmental, and compliance perspectives before prototype production.

FAQ

How do I know what battery voltage my equipment needs?

Check the equipment’s rated input voltage, motor or controller specifications, and existing battery specifications. The battery’s nominal and full-charge voltage should both be considered.

How do I calculate the battery capacity I need?

Battery energy can be estimated using voltage × capacity. The required capacity then depends on equipment power consumption, expected operating time, and operating conditions.

Should I choose NMC or LiFePO4?

The choice depends on the application. NMC may be suitable when energy density and compact design are important, while LiFePO4 may be considered for applications requiring stable operation and repeated cycling.

What information does a battery manufacturer need?

Useful information includes voltage, capacity, current, operating time, dimensions, charging requirements, temperature range, communication protocols, and certification requirements.

Can the battery pack be customized to fit my equipment?

Yes. Custom battery packs can be designed around specific electrical specifications, installation dimensions, connectors, mounting structures, and communication requirements.