How to Build a Battery Load Profile Before Requesting a Custom Pack

A custom battery project often begins with a few basic requirements:

“We need a 400V battery.”

“The machine should operate for eight hours.”

“The motor is rated at 20kW.”

These details are useful.

But they are not yet a load profile.

A motor does not necessarily operate at its rated power for the entire day.

A lifting system may draw high current for only a few seconds.

A pump may run continuously for an hour, stop for twenty minutes, and then restart.

A refuse collection vehicle may complete hundreds of short lifting cycles while spending much of the route in standby.

The battery experiences all of these operating phases differently.

That is why a reliable custom battery system cannot be sized from voltage, rated power, or desired runtime alone.

It must be evaluated around how the equipment consumes power over time.

That operating picture is the battery load profile.

What Is a Battery Load Profile?

A battery load profile is a time-based description of the electrical demand placed on the battery.

It should show more than one maximum value.

A useful profile may include:

Continuous power
Normal operating current
Startup current
Short-duration peak current
Peak duration
Peak frequency
Standby consumption
Auxiliary loads
Operating sequence
Idle and recovery periods
Daily working hours
Charging opportunities
Regenerative current, where applicable

In simple terms, it answers:

What is the equipment doing, how much power does each activity require, and how long or how often does it occur?

This information helps an engineering team evaluate:

Required usable energy
Continuous current capability
Peak current capability
Cell configuration
Voltage-drop behavior
Thermal requirements
Protection thresholds
Charging strategy
Cable and connector sizing
BMS control logic

A battery should not only contain enough energy.

It must deliver that energy in the way the machine requires it.

Why Rated Motor Power Is Not a Complete Load Profile

A motor nameplate may list rated voltage, rated power, rated current, and speed.

That information is valuable, but it does not describe the complete equipment cycle.

For example, a 20kW motor may:

Operate near 20kW continuously
Reach 20kW only during startup or lifting
Normally operate at 8–12kW
Spend significant time at low load
Drive a pump whose demand changes with pressure
Experience regenerative energy during lowering or braking

These scenarios can require different battery architectures.

A battery designed for a stable 20kW continuous load faces a different thermal challenge from a battery that delivers 40kW for ten seconds every two minutes.

The average energy consumption may even be similar.

But the current profile, heating behavior, voltage drop, BMS limits, and cell requirements may be very different.

The nameplate is a starting point.

The operating profile provides the engineering context.

Start by Dividing the Equipment Cycle Into Operating Phases

The easiest way to begin a load profile is to divide one normal working cycle into separate phases.

For a lifting platform, the phases might be:

Standby
Motor startup
Lifting
Holding position
Lowering
Travel or repositioning
Idle before the next cycle

For a pump-driven vehicle:

Standby
Pump startup
Low-pressure operation
Normal-pressure operation
High-pressure operation
Vehicle movement
Pump shutdown
Idle or refill period

For a refuse collection vehicle:

Vehicle travel
Approach and positioning
Lift initiation
Container lifting
Holding
Container lowering
Auxiliary-system operation
Standby before the next collection point

Each phase should be evaluated separately.

Do not begin by trying to calculate the entire working day as one average number.

Averages are useful later, but they can hide the short events that often determine battery current capability.

Record Six Values for Each Operating Phase

For every phase, collect the following information where possible.

1. Operating Voltage

Record the actual voltage range expected by the equipment, not only the nominal platform name.

Include:

Minimum accepted voltage
Normal operating voltage
Maximum accepted voltage
Controller undervoltage limit
Controller or inverter maximum input
Charging voltage range

A system described as “400V” may operate across a much wider range.

The same principle applies to 800V and project-specific platforms.

2. Normal Power or Current

Record the electrical demand during normal operation.

This can be expressed as:

Power in watts or kilowatts
Current in amps
Both power and current, where available

If only two values are known, the third can be estimated using:

Power = Voltage × Current

or:

P = V × I

However, the calculation should use the actual operating voltage at that moment whenever possible, not only nominal voltage.

3. Peak Power or Peak Current

Identify short high-load events such as:

Motor startup
Lift initiation
Pump acceleration
Rapid movement
Hydraulic pressure increase
Simultaneous auxiliary loads
Emergency operation

Record:

Peak current or power
How long the peak lasts
How frequently it occurs
Battery voltage during the event
Whether the controller limits the peak

Peak magnitude alone is not enough.

A 300A peak lasting 500 milliseconds is different from a 300A load lasting 30 seconds.

4. Duration

Record how long each phase lasts.

Examples:

Startup: 2 seconds
Lifting: 25 seconds
Holding: 10 seconds
Lowering: 20 seconds
Idle: 90 seconds

Duration helps convert power into energy.

A simplified calculation is:

Energy = Power × Time

If power is measured in kilowatts and time in hours:

Energy in kWh = Power in kW × Time in hours

Short phases may contribute little total energy but still create important current and thermal requirements.

5. Frequency

Record how often the phase occurs.

Examples:

Six lift cycles per hour
Forty pump starts per shift
Three hundred refuse-container cycles per day
Continuous operation for two hours
One emergency peak per working day

Frequency helps distinguish an occasional event from a repeated stress condition.

A high-current event that occurs once during startup is different from the same event occurring every minute throughout an eight-hour shift.

6. Environmental and Thermal Conditions

Record the conditions during the phase.

These may include:

Ambient temperature
Battery starting temperature
Indoor or outdoor use
Enclosure ventilation
Airflow
Direct sunlight
Cold-start conditions
Dust or water exposure
Equipment movement or vibration

The same electrical profile can produce different battery behavior in a ventilated indoor machine and a sealed vehicle enclosure operating in summer heat.

A Simple Load-Profile Worksheet

The following table can be used for an initial project discussion.

Add notes for:

Ambient temperature
Daily working hours
Cycles per day
Available charging time
Reserve requirement
Regenerative current
Measurement source
Uncertain or estimated values

The first version does not need to be perfect.

Its purpose is to identify what is already known and which values still need verification.

Distinguish Measured Data From Estimated Data

A useful requirement document should clearly label the source of every value.

Possible labels include:

Measured: Recorded from the actual equipment
Controller data: Exported from inverter, motor controller, or vehicle logs
Nameplate: Taken from the component rating plate
Supplier data: Provided by the motor, pump, or controller manufacturer
Calculated: Derived from known voltage, current, power, or runtime
Estimated: Based on expected operation but not yet verified
Target: A project objective rather than existing measured behavior

This distinction matters.

A measured 180A operating current carries different confidence from an estimated 180A based on motor rating.

Estimated values are still useful.

They simply should not be presented as confirmed measurements.

This allows the engineering team to identify which assumptions may need testing during prototype development.

Include Auxiliary Loads

The main motor or pump is not always the only load connected to the battery.

A complete profile should include auxiliary systems such as:

Cooling pumps
Fans
Heaters
Control electronics
Lighting
Displays
PDU loads
Hydraulic valves
Communication modules
DC/DC converters
Sensors
Cabin or operator equipment

An individual auxiliary load may appear small.

But a 500W control and cooling load operating for eight hours consumes:

0.5kW × 8h = 4kWh

That can be significant when calculating daily energy demand.

Auxiliary systems may also continue operating while the main motor is idle, which means they can affect runtime more than their peak power suggests.

Separate Energy Requirements From Power Requirements

One of the most important load-profile principles is the difference between energy and power.

Energy Answers:

How long can the equipment operate?

It is usually expressed in:

Wh
kWh
Ah at a defined voltage

Power Answers:

How much electrical demand must the battery support at a given moment?

It is usually expressed in:

W or kW
A at a defined voltage

A battery may contain enough energy for an entire shift but still be unable to provide the startup current.

Another battery may provide very high peak current but contain too little energy for the required runtime.

A complete design must satisfy both.

This is why “we need eight hours of operation” is not enough to select a battery.

Eight hours at 2kW is very different from eight hours with repeated 30kW peaks.

Do Not Use the Highest Possible Load as the Daily Average

When information is incomplete, project teams sometimes use the maximum motor rating for the entire operating period.

This can produce a heavily oversized battery.

For example:

A 30kW motor does not necessarily consume 30kW for eight continuous hours.

If it did, the theoretical energy requirement would be:

30kW × 8h = 240kWh

But if the equipment operates at:

30kW for short lifting events
8kW during movement
1kW during standby
Long idle periods between cycles

the actual daily energy may be much lower.

The battery still needs to support the 30kW event.

But capacity should be based on the complete operating cycle, not the maximum rating multiplied by the entire shift.

Oversizing is not automatically safer.

It can increase:

Weight
Volume
Cost
Charging time
Mechanical-integration difficulty
Cooling requirements

The objective is not the largest possible battery.

It is the correct battery for the verified load.

Do Not Ignore Low-Voltage Conditions

Peak current is often highest when battery voltage is lowest.

For approximately constant power:

Current = Power ÷ Voltage

If the equipment requires 40kW:

At 500V:

40,000 ÷ 500 = 80A

At 400V:

40,000 ÷ 400 = 100A

This means the battery and related high-voltage components should not be evaluated only at nominal voltage.

The profile should consider:

Minimum operating voltage
Expected voltage sag
Low state of charge
Cold conditions
Peak load
Controller undervoltage threshold

A system may appear suitable at nominal voltage but reach current or voltage limits near the lower end of the operating range.

Document Regenerative Conditions

Some equipment may return energy to the battery during:

Lowering
Deceleration
Braking
Motor overrun
Load release

This should be documented separately from discharge demand.

Important information includes:

Maximum regenerative current
Typical regenerative current
Regeneration duration
Frequency
Battery state of charge when regeneration occurs
Controller limits
Whether regeneration can be disabled or redirected

A battery near full charge may have limited ability to accept regenerative energy.

The BMS, controller, and operating strategy must respond appropriately.

Do not assume regeneration always increases practical runtime.

Its value depends on the equipment cycle and the system’s ability to accept and control the returned energy.

Include the Charging Window in the Load Profile

A battery requirement is incomplete without a charging schedule.

Record:

When the equipment can charge
How long each charging window lasts
Available charging power
Onboard or external charger
Required return-to-service time
Whether opportunity charging is possible
Whether the equipment must operate while connected
Whether the charger communicates with the BMS

Two machines with the same daily energy consumption may require different batteries.

Machine A can charge for one hour between shifts.

Machine B must operate all day and only charge overnight.

Machine C receives several short opportunity-charging sessions.

The available charging windows affect:

Required capacity
Charging rate
Thermal management
Cell selection
Charger size
Infrastructure
Battery reserve

The operating and charging profiles should be evaluated together.

Example 1: Lifting Equipment

A simplified lifting cycle might look like this:

The battery must be evaluated for:

Repeated 35kW startup events
Sustained 22kW lifting periods
Total cycles per shift
Heat accumulation
Regenerative conditions
Standby energy
Charging opportunities
Required reserve

Using only the 35kW peak would not define capacity.

Using only average power would not define peak-current capability.

The complete cycle is required.

Example 2: Pump-Driven Utility Vehicle

A pump vehicle may have:

Pump startup: 45kW for 5 seconds
Normal operation: 18kW for 40 minutes
High-pressure operation: 30kW for 10 minutes
Vehicle auxiliaries: 1.5kW continuously
Idle/refill: 0.8kW for 20 minutes
Several operating sessions per day

Important questions include:

Does pressure change throughout operation?
How often does the pump restart?
Does the motor controller limit startup current?
Do fans or cooling pumps continue during idle?
Is charging available during refill periods?
Does outdoor temperature affect cooling?
How much reserve is needed at the end of the route?

This profile may emphasize sustained thermal load more than a lifting application with short peaks and long recovery periods.

Example 3: Refuse Collection Vehicle

A rear-lift refuse collection system may complete hundreds of short cycles during a route.

A cycle may include:

Vehicle positioning
Lift startup
Container movement
Holding
Lowering
Auxiliary hydraulic or electric operation
Standby while traveling to the next location

The daily energy of one cycle may appear small.

But repetition changes the engineering requirement.

The battery may experience:

Frequent peak current
Repeated voltage drop
Cumulative heating
Long total working time
Vibration
Outdoor temperature variation
Limited charging during the route

This is why cycle count and frequency must be documented, not only the power of one lifting event.

Lifirst’s current custom battery engineering page identifies lifting equipment, refuse collection systems, pump-driven vehicles, and other industrial mobility equipment as project-based applications evaluated around real load profile, duty cycle, installation, charging, communication, and environment.

What If the Equipment Does Not Yet Exist?

New equipment development may not have measured load data.

That does not prevent an initial engineering discussion.

Begin with:

Motor or pump specifications
Controller or inverter information
Expected mechanical load
Expected operating sequence
Estimated cycle time
Target daily operating hours
Similar existing equipment data
Planned charging method
Available installation space
Environmental requirements

Mark uncertain values clearly as estimates.

During development, the project may then use:

Controller logs
Current sensors
Voltage logging
Power analyzers
Temperature sensors
Prototype testing
Equipment integration trials

The load profile should become more accurate as the project progresses.

It is normal for early-stage engineering inputs to contain assumptions.

The important point is to identify those assumptions rather than treating them as validated data.

What If the Equipment Already Uses a Battery?

A replacement project should collect information from the existing system.

Useful inputs include:

Existing battery nominal and operating voltage
Capacity
Chemistry
Continuous and peak-current ratings
BMS fault records
Typical state of charge at the end of a shift
Charging time
Temperature history
Voltage sag during startup
Known shutdown events
Operator complaints
Actual daily runtime
Existing dimensions and weight
Connector and communication information

Also document why the existing battery is being replaced.

Possible reasons include:

Insufficient runtime
Startup voltage drop
Overtemperature
Slow charging
High weight
Limited cycle life
Poor mechanical fit
Unavailable replacement parts
Communication incompatibility
New equipment requirements

The objective should not be to copy the old battery automatically.

It should be to understand which parts of the old system worked and which problems the new system must solve.

A Load Profile Is Not the Final Battery Specification

A load profile is an input to engineering evaluation.

It does not independently define:

Final cell chemistry
Series-parallel configuration
Cooling method
BMS thresholds
Pack dimensions
Connector selection
Exact usable capacity
Charging power
Certification scope

Those decisions also depend on:

Voltage architecture
Installation space
Weight limit
Environmental conditions
Required cycle life
Charging strategy
Supply-chain requirements
Safety and validation
Project quantity
Cost targets

A strong load profile improves the quality of those decisions.

It does not replace the engineering process.

What to Submit to Lifirst

For an initial project review, prepare the best available version of:

Equipment type
Work the machine performs
Existing or target voltage range
Motor, controller, inverter, or pump information
Normal power or current
Peak power or current
Peak duration
Frequency of peak events
Daily operating sequence
Cycles per hour or day
Required runtime
Auxiliary loads
Regenerative conditions
Charging method and charging windows
Installation dimensions
Weight limitations
Temperature and environmental conditions
Communication requirements
Prototype and production expectations

Values may be measured, calculated, estimated, or targeted.

Label the source and confidence of each value.

Lifirst’s current custom high-voltage process begins with requirement review covering equipment type, voltage, capacity, continuous and peak current, expected runtime, charging, installation, and operating environment before moving into system configuration, prototype evaluation, validation, and project production.

Submit your battery requirements for engineering review

Conclusion

A battery load profile is not a single maximum number.

It is the story of how the machine uses energy over time.

A useful profile should show:

What the equipment does
How much power each activity requires
How long each activity lasts
How frequently it repeats
Which events create peak current
How much auxiliary power is consumed
When the equipment can recharge
How temperature and environment affect operation

This information allows the battery to be evaluated around the real machine rather than an assumption.

At Lifirst, the objective is not to select a battery from a fixed catalog and force the equipment to adapt.

It is to understand the application, convert its work cycle into engineering requirements, and develop the battery system around the complete operating profile.

Voltage begins the electrical conversation.

The load profile explains what the battery must actually do.

Frequently Asked Questions

What Is the Difference Between a Load Profile and a Duty Cycle?

A load profile describes how voltage, current, and power change over time.

A duty cycle describes how frequently and for how long the equipment operates in each working state.

They are closely related. The duty cycle provides the timing and repetition required to interpret the electrical load profile.

Can I Request a Custom Battery Without Measured Load Data?

Yes.

An initial review can begin with motor or pump specifications, controller data, expected operating sequence, runtime targets, and estimated loads.

Estimated values should be clearly labeled and may need verification during prototype or equipment testing.

Is Peak Current More Important Than Average Current?

Both are important for different reasons.

Peak current affects startup, lifting, acceleration, voltage drop, and short-duration battery capability.

Average and continuous current affect energy consumption, heat accumulation, runtime, and cooling requirements.

How Long Should Peak Current Be Measured?

Record the complete duration of the event and, where possible, the shape of the current over time.

A brief millisecond spike, a five-second startup event, and a thirty-second lifting load create different requirements even when the maximum current is the same.

Should Standby Power Be Included?

Yes.

Standby, controls, cooling, communication, displays, and auxiliary loads may operate for long periods and contribute significantly to daily energy consumption.

How Much Safety Margin Should Be Added?

There is no universal percentage suitable for every project.

Margin depends on measurement confidence, temperature, battery aging, operating variation, charging access, reserve requirements, and equipment criticality.

It should be evaluated during engineering review rather than applied as one fixed rule.

Can Motor Nameplate Data Replace Equipment Measurements?

No.

Nameplate data is a useful starting point, but it does not show the real operating cycle, startup behavior, partial-load operation, auxiliary consumption, controller limits, or environmental effects.

Does Regenerative Energy Reduce the Required Battery Capacity?

It may recover part of the energy in some applications, but the benefit depends on the amount, frequency, battery state of charge, controller behavior, and the system’s ability to accept regenerative current.

It should be measured or conservatively estimated rather than assumed.

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