How to Read LiPo Battery Model Numbers and Size Codes

A LiPo battery may be labeled with a number such as 451220, 603048, or 582540. At first glance, these numbers can look like capacity ratings or internal product codes. In many cases, however, they describe the approximate physical dimensions of the pouch cell.

For example, a 603048 cell is commonly interpreted as approximately:

• 6.0 mm thick

• 30 mm wide

• 48 mm long

This decoding method is useful, but it should not be treated as a universal standard. Different manufacturers may change the number of digits, reverse the dimension order, round measurements differently, or add prefixes and suffixes for chemistry, capacity, voltage, connector, or production revision.

More importantly, the size code usually describes the cell body—not necessarily the maximum dimensions of the finished battery assembly. A protection circuit, insulation, wires, connector, sealing edge, and required installation clearance can all increase the space needed inside the device.

This guide explains how common LiPo battery model numbers work, what the numbers do and do not tell you, and what must be confirmed before selecting a replacement cell or specifying a custom battery.

Key Takeaways

• Many pouch-cell model numbers represent thickness, width, and length.

• A common six-digit format is TTWWLL, but it is not a universal standard.

• Thickness is often expressed in tenths of a millimeter.

• Width and length are commonly expressed in whole millimeters.

• A 603048 cell is commonly read as 6.0 × 30 × 48 mm.

• Codes may contain five, six, seven, or more digits when dimensions fall below 1 mm or exceed 99 mm.

• Manufacturer prefixes and suffixes may indicate chemistry, voltage, capacity, connector, or product revision.

• The model number usually does not reliably identify capacity, discharge rate, maximum charge voltage, or protection functions.

• Cell dimensions and finished-battery dimensions are not always the same.

• Pouch sealing edges, tabs, wires, connectors, and protection circuits must be included in the mechanical evaluation.

• Two batteries with the same size code may still have different electrical characteristics.

• A datasheet and mechanical drawing should always take priority over assumptions based on the model number.

• Replacement selection must confirm voltage, capacity, current, connector, polarity, protection, and dimensions together.

• A battery should be tested in the final device before production approval.

The Quick Answer: What Do LiPo Battery Model Numbers Mean?

A common LiPo pouch-cell size code uses the following structure:

Thickness × Width × Length

For a six-digit code, this is often written as:

TTWWLL

The first two digits typically represent thickness in tenths of a millimeter. The middle two digits represent width in millimeters, and the final two digits represent length in millimeters.

Using this convention:

This is a practical first interpretation, not final proof of battery dimensions. The supplier’s specification table and dimensional drawing must still be checked.

How the Common Six-Digit LiPo Size Code Works

Consider the model number 603048.

It can be separated into three groups:

60 | 30 | 48

First Group: Thickness

The first two digits are often expressed in units of 0.1 mm.

Therefore:

60 ÷ 10 = 6.0 mm

The approximate cell thickness is 6.0 mm.

Second Group: Width

The next two digits normally represent the width in millimeters:

30 = 30 mm

Third Group: Length

The final two digits normally represent the length in millimeters:

48 = 48 mm

The resulting cell size is therefore approximately:

6.0 × 30 × 48 mm

ZERNE lists the 603048 model among its 3.7 V LiPo batteries from 500 to 1000 mAh, where its dimensions and electrical specifications can be compared with other models.

More LiPo Size Code Examples

Example 1: 451220

Separate the number as:

45 | 12 | 20

This commonly indicates:

• Thickness: 4.5 mm

• Width: 12 mm

• Length: 20 mm

The size is approximately:

4.5 × 12 × 20 mm

Example 2: 321447

Separate the number as:

32 | 14 | 47

This commonly indicates:

• Thickness: 3.2 mm

• Width: 14 mm

• Length: 47 mm

The size is approximately:

3.2 × 14 × 47 mm

Example 3: 582540

Separate the number as:

58 | 25 | 40

This commonly indicates:

• Thickness: 5.8 mm

• Width: 25 mm

• Length: 40 mm

The size is approximately:

5.8 × 25 × 40 mm

Example 4: 604040

Separate the number as:

60 | 40 | 40

This commonly indicates:

• Thickness: 6.0 mm

• Width: 40 mm

• Length: 40 mm

The size is approximately:

6.0 × 40 × 40 mm

ZERNE’s 50–500 mAh lithium polymer battery range includes models such as 451220 and 321447, allowing device developers to compare size, capacity, and internal resistance rather than selecting by dimensions alone.

Why Not Every LiPo Model Has Six Digits

The TTWWLL format works conveniently when:

• Thickness can be represented by two digits

• Width is below 100 mm

• Length is below 100 mm

• The manufacturer uses thickness–width–length order

• No additional product identifier is included

Real pouch cells do not always fit these conditions.

Dimensions Greater Than 99 mm

A cell with a length of 108 mm requires three digits to express its length. The code may therefore contain seven digits rather than six.

A supplier might represent a 9.5 × 17 × 108 mm cell as:

9517108

This can be separated as:

95 | 17 | 108

However, another manufacturer may use separators, leading zeros, a different grouping method, or an internal part number instead.

A longer model number should not be divided into equal two-digit groups automatically.

Thickness of 10 mm or More

The first group can also become ambiguous when the cell is 10 mm thick or more.

Some manufacturers continue using tenths of a millimeter and may need three digits for thickness. Others adapt the code to use whole millimeters, omit a zero, or create a separate internal naming rule.

For example, the digits “10” could theoretically be interpreted as:

• 1.0 mm under a strict tenths-of-a-millimeter rule

• 10 mm under a manufacturer-specific rule

• Part of a longer thickness field

• Part of an internal catalog number rather than a dimension

Do not decode a thick pouch cell without checking the supplier’s specification.

Thickness Below 1 mm

Ultra-thin cells can also require special notation. A manufacturer may use:

• A leading zero

• An additional digit

• A decimal point

• A letter prefix

• A proprietary model code

A code beginning with “05” could mean 0.5 mm under one system, but the same digits may be interpreted differently by another supplier.

Width or Length With Three Digits

When the width or length reaches 100 mm, possible formats include:

• A seven- or eight-digit continuous number

• Numbers separated by hyphens

• Numbers separated by slashes

• Decimal dimensions written in full

• A manufacturer-specific SKU with a separate size table

Without separators or a dimensional drawing, a long continuous code may have more than one possible interpretation.

LiPo Size Codes Are Common Conventions, Not Universal Standards

The most important rule is simple:

Never assume that every manufacturer uses the same model-number system.

Possible differences include:

• Thickness–width–length order

• Thickness–length–width order

• Width–length–thickness order

• Thickness in 0.1 mm units

• All dimensions in whole millimeters

• Rounded nominal dimensions

• Maximum dimensions instead of nominal dimensions

• Cell-body dimensions excluding sealing edges

• Finished-cell dimensions including insulation

• Internal catalog numbers unrelated to size

• Prefixes identifying chemistry or product family

• Suffixes identifying capacity or connector

• Revision numbers added to the basic size code

If a supplier provides a model called 603048, it should not automatically be considered mechanically interchangeable with every other battery carrying the same number.

The specification sheet must define what each part of the code means.

Model Number, Part Number, and Size Code Are Not Always the Same

Battery documentation may contain several identifiers.

Size Code

A size code describes physical dimensions, such as:

603048 = approximately 6.0 × 30 × 48 mm

Cell Model Number

A cell model may use the size code as its main identifier, but it may also contain letters or additional digits.

For example:

LP603048
ZN-603048
603048HV
603048-850

The added characters might refer to:

• Lithium polymer chemistry

• Manufacturer or product series

• High-voltage chemistry

• Nominal capacity

• Discharge-rate version

• Temperature version

• Production revision

These meanings are manufacturer-specific.

Finished Battery Part Number

A finished battery assembly may have its own part number because it includes more than the cell.

The finished part number may define:

• Cell model

• PCM or BMS

• NTC thermistor

• Wire gauge

• Cable length

• Connector

• Polarity

• Insulation

• Label

• Firmware

• Customer-specific revision

Two finished batteries can use the same pouch cell but have different part numbers because their protection circuits, connectors, or wiring are different.

Customer or Device Part Number

An OEM may also assign its own internal number to the completed battery. That number may not reveal any physical or electrical information.

When requesting a replacement, identify whether the number on the label is:

• A cell size code

• A battery supplier’s model

• A finished-pack part number

• A customer-specific material number

• A batch or date code

What the LiPo Model Number Usually Does Not Tell You

Even when the dimensions can be decoded correctly, the size code alone is incomplete.

Capacity

A 603048 model number does not mean that every cell of this size has exactly the same mAh rating.

Capacity can vary because of differences in:

• Electrode formulation

• Coating thickness

• Internal layer count

• Energy-density design

• Maximum charge voltage

• Tab structure

• Manufacturing process

• Discharge conditions

• Product age and specification tolerance

One 603048 cell may therefore have a different capacity from another 603048 cell.

Nominal Voltage

The geometric code usually does not identify whether the cell is rated at:

• 3.6 V

• 3.7 V

• 3.8 V

• 3.85 V

• Another nominal voltage

It also does not reliably identify maximum charge voltage. This must be confirmed separately because standard and high-voltage LiPo cells require different charging limits.

Maximum Charge Voltage

A cell that charges to 4.2 V should not be replaced with a 4.35 V or 4.4 V cell unless the charger, protection thresholds, device design, and battery specification have been evaluated together.

The same external dimensions do not guarantee charger compatibility.

Discharge Rate

The model code does not normally show:

• Continuous discharge current

• Peak discharge current

• Peak duration

• C rating

• Voltage-drop performance

• Internal resistance

• Temperature rise

A cell that fits mechanically may still be unable to support the device load.

Protection Circuit

The number does not confirm whether the battery includes:

• Overcharge protection

• Over-discharge protection

• Over-current protection

• Short-circuit protection

• Temperature sensing

• Cell balancing

• Fuel gauging

• Communication

A bare pouch cell and a protected battery assembly can use the same basic cell code.

Connector and Polarity

The code does not normally specify:

• Connector manufacturer

• Connector series

• Pin count

• Polarity

• Pinout

• Wire gauge

• Wire length

• Cable exit direction

Two batteries can use identical cells while having reversed polarity at the connector.

Cell Chemistry and Performance Version

Standard-energy, high-density, high-rate, low-temperature, fast-charge, and high-voltage cells can share similar dimensions.

Geometry alone does not identify the internal cell design.

How to Read the Rest of a LiPo Battery Label

A complete battery label may include several types of information.

Consider a hypothetical label:

603048
3.7 V
850 mAh
3.145 Wh
1S1P
PCM + NTC

Each item describes a different characteristic.

603048

The cell is approximately 6.0 × 30 × 48 mm under the common size-code convention.

3.7 V

This is the nominal voltage, not the full-charge voltage.

850 mAh

This is the rated capacity under the manufacturer’s specified test conditions.

3.145 Wh

Watt-hours indicate nominal stored energy:

3.7 V × 0.85 Ah = 3.145 Wh

1S1P

The assembly contains one series group and one cell in that group.

For a single pouch cell, this designation may be omitted.

PCM

A protection circuit is included. Its exact thresholds and current ratings still need to be confirmed.

NTC

A thermistor is included for temperature sensing. The label does not necessarily show whether the PCM, charger, or host device reads it.

Size Code vs Capacity Code

Model numbers are sometimes confused with capacity because both are written as continuous digits.

For example:

• 603048 may be a size code

• 850 may be the capacity in mAh

• 3.7 may be nominal voltage

• 1C may be the charge or discharge-rate specification

These values should not be combined or interpreted as one code unless the manufacturer explicitly defines the format.

A product identified as “603048 850mAh” usually means:

• Model or size: 603048

• Rated capacity: 850 mAh

It does not mean that “850” is part of the cell dimensions.

Cell Dimensions vs Finished Battery Dimensions

One of the most common mechanical-selection mistakes is using the cell code as the maximum finished-battery size.

A completed battery may include:

• Aluminum-laminated pouch

• Side and top sealing edges

• Positive and negative tabs

• Tab insulation

• Protection circuit

• Nickel connections

• NTC thermistor

• Wires

• Connector

• Tape or heat-shrink insulation

• Foam or protective pads

• Identification label

These components can increase thickness, width, length, or the required installation envelope.

Bare Cell Size

This may describe only the pouch-cell body before the protection circuit, wire, and connector are added.

Finished Battery Size

This includes the assembled battery and its insulation. The protection circuit may be positioned:

• At the top of the cell

• Along one side

• Folded over the pouch

• On a separate cable

• Inside a plastic enclosure

Each arrangement changes the final dimensions.

Installation Envelope

The device needs more than the battery’s measured dimensions. The installation envelope may also need to accommodate:

• Manufacturing tolerances

• Assembly clearance

• Cable routing

• Connector access

• Wire bend radius

• Adhesive or foam

• Mechanical supports

• Thermal expansion

• Permitted cell expansion over service life

• Enclosure deformation

• Vibration and drop protection

The battery should not be forced into a rigid cavity based only on its nominal new-cell thickness.

For especially tight products, a thin lithium polymer battery should be evaluated using a complete mechanical drawing rather than only a catalog size code.

Which Part of a Pouch Cell Is Measured?

Terms such as thickness, width, and length may appear straightforward, but the measurement boundaries can differ.

Thickness

The drawing should state whether thickness refers to:

• The main active cell body

• The maximum pouch thickness

• The battery after insulation

• The battery at a defined state of charge

• A nominal or maximum value

Width

The width may include or exclude the side sealing edges, depending on the supplier’s drawing.

Length

The length may refer to:

• The active cell body

• The sealed pouch

• The pouch including the top seal

• The cell including tabs

• The finished battery including the protection circuit

Wire and Connector Length

Cable length should also be defined precisely. It may be measured:

• From the cell edge to the connector housing

• From the PCM edge to the connector

• Along the wire centerline

• To the end of the terminals

• To the front or rear of the connector housing

A dimension without clearly defined reference points can create assembly problems even when the numerical value appears correct.

Nominal Dimensions, Maximum Dimensions, and Tolerances

A battery specification should distinguish between nominal and maximum size.

Nominal Dimension

A nominal dimension is the target or identifying size. It is useful for model classification but may not represent the largest acceptable production unit.

Maximum Dimension

A maximum dimension is the upper limit that the finished battery should not exceed under the specified measurement conditions.

For device integration, maximum dimensions are usually more important than nominal dimensions.

Manufacturing Tolerance

Pouch-cell dimensions naturally have production tolerances. The finished battery can also vary due to:

• Pouch formation

• Electrolyte filling

• Sealing

• Tab folding

• PCM placement

• Soldering or welding

• Insulation tape

• Label application

• Cable routing

The mechanical drawing should therefore specify acceptable tolerances for the finished assembly.

Service-Life Allowance

Pouch cells may change thickness during operation and aging. The device structure should not puncture, sharply bend, or place uncontrolled pressure on the battery.

The amount and direction of permitted expansion depend on the cell, operating conditions, mechanical design, and supplier requirements. It should be defined during battery and enclosure development rather than estimated from the printed model number.

Can Two Batteries With the Same Model Number Be Interchanged?

Not automatically.

Two batteries both labeled 603048 may differ in:

• Capacity

• Nominal voltage

• Maximum charge voltage

• Internal resistance

• Continuous current

• Peak current

• Charge rate

• Cycle life

• Operating temperature

• Protection circuit

• NTC value

• Connector

• Polarity

• Cable length

• Finished dimensions

• Certification status

They may share approximate cell geometry while being electrically or mechanically incompatible.

A replacement battery should match the original design requirements, not merely the six-digit size code.

How to Select a Replacement LiPo Battery

1. Record Every Marking on the Original Battery

Photograph or document:

• Model number

• Voltage

• Capacity

• Watt-hours

• Manufacturer

• Date or batch code

• Polarity symbols

• Certification markings

• Connector

• Wire colors

• Any PCM, NTC, or communication information

Do not rely on one number alone.

2. Confirm the Battery Chemistry and Charge Limit

Determine:

• Nominal voltage

• Maximum charging voltage

• Charging method

• Number of series groups

• Whether the cell is a standard- or high-voltage design

A mechanically compatible cell with an incorrect charge limit is not a suitable replacement.

3. Measure the Available Device Space

Measure the maximum usable:

• Thickness

• Width

• Length

Also record:

• Cable-routing area

• Connector location

• Cable exit direction

• Keep-out zones

• Mounting surfaces

• Required assembly clearance

The usable space may be smaller than the visible cavity because of ribs, screws, circuit boards, antennas, or moving parts.

4. Confirm Capacity and Runtime Requirements

The replacement should provide the required runtime without exceeding the device’s space, weight, charging, or thermal limits.

A higher-capacity battery is not automatically compatible. It may be:

• Larger

• Heavier

• Slower to charge

• Designed for a different current

• Incompatible with the fuel-gauge calibration

5. Check Continuous and Peak Current

Provide the battery supplier with:

• Standby current

• Typical operating current

• Maximum continuous current

• Startup current

• Peak current

• Peak duration

• Repeating pulse load

• Charging current

This is particularly important for motors, pumps, heaters, radios, displays, and processors with high startup demand.

6. Match the Connector and Polarity

Confirm the connector’s:

• Manufacturer

• Series

• Part number

• Pitch

• Pin count

• Mating connector

• Polarity

• Pinout

• Wire gauge

• Wire length

Wire color alone is not sufficient proof of polarity.

7. Confirm Protection and Temperature Sensing

Determine whether the battery requires:

• PCM or BMS

• Overcharge protection

• Over-discharge protection

• Over-current protection

• Short-circuit protection

• NTC thermistor

• Secondary fuse

• Fuel gauge

• Communication

A replacement with a different protection threshold may shut down too early or fail to protect the cell correctly.

8. Test the Battery in the Device

Validate:

• Mechanical fit

• Connector engagement

• Polarity

• Charging

• Full-charge voltage

• Runtime

• Peak-load response

• Device shutdown

• Low-battery reporting

• Temperature rise

• Cable movement

• Protection behavior

Production approval should be based on device-level testing, not only a comparison of label information.

How to Specify a New LiPo Battery for an OEM Device

When developing a new battery-powered product, start with device requirements rather than choosing a size code first.

Mechanical Requirements

Provide:

• Maximum cell or pack thickness

• Maximum width

• Maximum length

• Cavity drawing

• Restricted areas

• Cable exit direction

• Connector position

• Mounting method

• Weight limit

• Permitted expansion space

• Enclosure material

• Drop and vibration requirements

Electrical Requirements

Provide:

• Nominal device voltage

• Acceptable input-voltage range

• Maximum safe input voltage

• Typical current

• Maximum continuous current

• Peak current and duration

• Required runtime

• Charging voltage and current

• Device cutoff voltage

• Standby-current target

Protection Requirements

Provide:

• PCM or BMS functions

• Overcharge and over-discharge protection

• Charge and discharge over-current protection

• Short-circuit protection

• Number and location of temperature sensors

• Fuse requirements

• Fuel-gauge requirements

• Communication protocol

Connection Requirements

Provide:

• Connector manufacturer and part number

• Mating connector

• Pinout

• Polarity

• Wire gauge

• Cable length

• Wire colors

• NTC or communication leads

• Strain-relief requirements

Product and Compliance Requirements

Provide:

• Target market

• Application type

• Expected annual volume

• Certification requirements

• Transportation requirements

• Cycle-life target

• Operating temperature

• Storage conditions

• Sampling and validation plan

ZERNE’s custom Li-polymer battery service can combine the selected pouch cell with the required protection circuit, temperature sensor, wire, connector, insulation, and mechanical structure for an OEM device.

Common LiPo Model Number Mistakes

A Practical Model-Number Verification Checklist

Before approving a LiPo battery, confirm the following.

Identity

• Full model number

• Cell manufacturer

• Finished battery part number

• Product revision

• Date or batch code

Dimensions

• Thickness

• Width

• Length

• Whether dimensions are nominal or maximum

• Measurement boundaries

• Dimensional tolerances

• Finished-pack size

• PCM location

• Connector and cable envelope

• Required device clearance

Electrical Specification

• Nominal voltage

• Maximum charge voltage

• Rated capacity

• Minimum capacity

• Watt-hours

• Internal resistance

• Continuous current

• Peak current and duration

• Charging current

• Discharge cutoff

Protection

• Overcharge threshold

• Over-discharge threshold

• Charge over-current threshold

• Discharge over-current threshold

• Short-circuit response

• Temperature sensing

• NTC specification

• Recovery behavior

• PCM or BMS current consumption

Connection

• Connector manufacturer

• Connector part number

• Mating connector

• Pinout

• Polarity

• Wire gauge

• Cable length

• Cable exit direction

• Strain relief

Validation

• Mechanical-fit test

• Charging test

• Runtime test

• Peak-load test

• Temperature-rise test

• Protection-function test

• Low- and high-temperature test

• Cycle test

• Device-level approval

Conclusion

LiPo battery model numbers often provide a useful first indication of cell size. Under the common TTWWLL convention, a model such as 603048 represents a cell approximately 6.0 mm thick, 30 mm wide, and 48 mm long.

That convention is not universal. Codes may use a different dimension order, contain additional digits, include proprietary prefixes or suffixes, or represent nominal cell-body dimensions rather than the maximum size of the completed battery.

The size code also does not reliably identify capacity, maximum charge voltage, discharge current, protection functions, connector, or polarity. Two batteries with the same geometric code may therefore be unsuitable replacements for one another.

Use the model number to begin the selection process, then confirm the datasheet, dimensional drawing, finished-pack construction, electrical ratings, connection details, and device test results. This prevents a cell that appears correct on paper from causing charging, runtime, thermal, protection, or assembly problems in the final product.

Frequently Asked Questions

What does 603048 mean on a LiPo battery?

Under a common pouch-cell naming convention, 603048 indicates approximate dimensions of 6.0 mm thickness, 30 mm width, and 48 mm length. Confirm the supplier’s datasheet because naming systems can differ.

What does 451220 mean on a LiPo battery?

It commonly represents a cell approximately 4.5 × 12 × 20 mm. The first two digits indicate thickness in tenths of a millimeter, followed by width and length in millimeters.

Are all LiPo battery model numbers six digits?

No. Some contain five, seven, eight, or more digits. Longer dimensions, ultra-thin cells, manufacturer prefixes, capacity suffixes, and proprietary part-number systems can change the format.

Is TTWWLL an official LiPo battery standard?

It is a widely used naming convention, but it is not a universal standard followed identically by every manufacturer. Always confirm the dimension order and units.

Does a LiPo model number show its capacity?

Usually not. Capacity is typically listed separately in mAh. Cells with the same external dimensions may have different rated capacities.

Does the size code include the protection circuit?

Not necessarily. It often refers to the pouch cell itself. The PCM, insulation, wires, and connector can increase the finished battery dimensions.

Can I replace a battery with another one carrying the same model number?

Only after confirming voltage, maximum charge voltage, capacity, current capability, protection circuit, connector, polarity, NTC, finished dimensions, and device compatibility.

Why is the finished battery larger than its size code?

The completed assembly may include pouch sealing edges, tabs, a protection circuit, nickel connections, tape, labels, wires, and a connector. Manufacturing tolerances and installation clearance also require additional space.

Which comes first in a LiPo size code: length or thickness?

Thickness commonly comes first, followed by width and length. Some manufacturers use a different order, so the datasheet or mechanical drawing should be checked.

What if one LiPo dimension is greater than 99 mm?

The manufacturer may use an extra digit, separators, leading zeros, or a proprietary model number. Do not divide a seven- or eight-digit code into equal groups without confirming the supplier’s convention.

Is a 603048 battery always 850 mAh?

No. Although 850 mAh is a possible specification for this size, capacity can vary with cell design, chemistry, charge voltage, and manufacturer. Use the stated capacity rather than estimating it from the model number.

Should I use nominal or maximum dimensions for device design?

Use the supplier’s maximum finished-battery dimensions and specified tolerances. The device should also provide appropriate assembly, cable-routing, and service-life clearance.

What information should I send when requesting a custom LiPo battery?

Provide the maximum battery space, voltage, capacity, continuous and peak current, charging method, runtime, connector, polarity, cable length, protection functions, temperature range, and application requirements. A cavity drawing is particularly useful for space-constrained products.