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UL1642 of LiPo Battery

By September 7th, 2022LiPo Battery

What is UL1642? What does UL1642 stand for and what test items does UL1642 have? This article will bring you more answers than this.

UL1642 incorporates essential requirements for a wide variety of products specified by UL.

UL1642 are based on sound engineering principles, the results of research and experimentation, operating experience, and the advice and recommendations of manufacturers, users, testing agencies, and other organizations or individuals with professional experience.

One of the basic conditions that lipo battery manufacturers must meet when manufacturing battery products is to comply with the requirements of this UL1642.

If a product can only comply with the provisions of this standard as written, it is not sufficient to determine whether the product complies with this UL1642.

If the material or design used in a battery product does not meet the technical requirements of this standard, it cannot be considered to comply with UL1642.

UL is not responsible for the customer’s product in performing safety tests requested by the customer; UL only provides a professional judgment of the product based on certain time constraints and requirements considered in the current situation; UL is not responsible for hazards caused by the product.

Many of the tests in this UL1642 must include adequate safety measures to protect people and property because of inherent hazards.

UL1642 Test Items of Lithium Polymer Battery

  • T.10 Short-Circuit Test
  • T.11 Abonormal Charging Test
  • T.12 Forced-Discharge Test
  • T.13 Crush Test
  • T.14 Impact Test
  • T.15 Shock Test
  • T.16 Vibration Test
  • T.17 Heating Test
  • T.18 Temperature Cycling Test
  • T.19 Low Pressure (Altitude Simulation) Test

1. Introduction of UL1642

These requirements include primary (non-rechargeable) and secondary (rechargeable) lithium polymer batteries. These cells include metallic Li or Li alloys or Li ions, and battery pack configurations of one cell, two cells or more cells in series/parallel.

These requirements include technician and user replaceable applications.

The goal of these requirements is to reduce the risk of fire or explosion of lithium batteries when used in products. Final acceptance of these lithium polymer batteries is dependent on their use in a complete product that meets UL 1642 certification for such products.

These requirements are also intended to help reduce the risk of fire or explosion to the user when replacing lipo batteries.

These requirements apply to the replacement of lipo batteries containing ≤5 g of lithium. For lipo batteries containing more than 5 g of lithium, although these lipo may meet this requirement, they must be subjected to further testing and inspection to determine if they can be safely placed in service.

These requirements apply to user-replaceable lithium polymer batteries containing ≤4 g lithium metal and ≤1 g lithium metal per cell. Batteries containing ≥4 g lithium metal or >1 g lithium metal per cell require additional testing and inspection to determine if they can be safely placed in service.

This requirement does not include the risk of toxic hazards caused by ingestion of lithium polymer batteries and their components or hazardous conditions for people when opening batteries.

Certain features, characteristics or parts of the product, materials or the entire system and the requirements of this standard arise under various, while including fire, electric shock, and other situations that may cause harm to persons, shall have additional appropriate parts and end product requirements to evaluate to ensure that the product is within an acceptable level of safety.

2. Summary of UL1642

When a measured value is followed by another value in parentheses, the second value can only be an approximation, while the first is the required value.

3. Glossary of UL1642

Battery – (1) a single cell or (2) a group of cells connected in series/parallel.

Battery, Primary – A battery that can only be discharged once and cannot be recharged and discharged repeatedly.

Battery, Secondary – A battery that can be discharged and recharged many times.

Battery, Technician-replaceable – A battery that can only be serviced and repaired by a professionally trained technician.

Battery, User-replaceable – A battery that can be replaced by the user.

Cell – a separate electrochemical cell with positive and negative poles.

Charged, fully- a battery that has been fully charged and stored in accordance with the electrical capacity specified by the manufacturer.

Component, current-limity – any component used to limit current under abnormal conditions, including resistors, fuses or thermal cut-off components. 3.

Current, Abnormal charge – Charging of a single cell or battery in an abnormal manner.

Discharged, Force – Forced discharge of a battery in series with an external power supply to allow the battery to eventually become a reverse polarity battery.

Discharged, full – A battery is considered fully discharged if a 100 ohm resistor is connected and the short circuit current is less than 1 mA and the closed circuit voltage of the battery is less than 0.2 V.

Discharged, half – half the rated capacity of the battery is discharged from a full battery.

Explosion – When a cell or part of a battery is forcibly disassembled and the cell or battery case is ruptured or split in half or more.

Toxic materials – Industrial products marked as toxic in the sax reference guide for hazardous materials.

Temperature – approximately 23°C (73°F).

Venting – condition in which battery or cell electrolyte escapes as vapor, liquid, or droplets from the valve or intended sealing mechanism.

4. Composition of UL1642

The case of a lithium polymer battery must be strong and rigid enough to withstand extreme pressure and not catch fire. Replacement lithium batteries must be strong enough not to cause injury to persons.

Replacement batteries must not contain pressurized vapors or emit toxic vapors or liquids that are harmful to the eyes or the battery case under normal laboratory conditions, the toxic liquid that is emitted upon impact at 23 ℃ must be less than 5 ml.

When using lithium polymer batteries, protective measures must be taken to prevent abnormal charging current. The test battery has an acceptable charging current Ic (see 18.1), under abnormal conditions, it should be used in end-product protection measures:

  1. Two blocking parts, such as diodes.
  2. A blocking part and a current limiting part, such as a resistor or fuse. The current limiting part must limit the load current to 1/3rd of its value (not the normal load test value).

Exception 1: An end product application that does not require load protection in a battery circuit where the battery is not to be exposed to charging current.

Exception 2: The battery has been determined not to present an explosion hazard.

Exception 3: Rechargeable batteries require only a current limiting component, not a blocking component.

5. Performance of UL1642

Technician-Replaceable Battery

Technician replacement lithium polymer batteries shall be tested in accordance with the requirements of sections 10 to 19, of which 12 (forced discharge test) applies only to cells used in battery packs. No fire or explosion shall occur under requirements 10 of the short-circuit test, and 14 of the impact test, 16 of the microvibration test, 18 of the thermal cycle test, or 19 of the height simulation test may not occur. In addition, the temperature of the cell or battery case shall not exceed 150℃ (302℉) during the short-circuit test.

Cells or batteries that could catch fire or explode during the battery abnormal charge test 11, 13 compression, 14 impact or 17 heat tests should be strictly limited and not used under conditions that could cause a fire resulting in an explosion. Cells and batteries subjected to 14 impact test, 16 vibration test, 18 thermal cycling test, and 19 height simulation test, battery leakage in these tests must meet the loss criteria in Table 5.1.

 

User-Replaceable Battery

User-replaceable batteries should be tested on 10-19 cells. The 12-forced discharge test is only applicable to multi-cell batteries. user-replacement cells or batteries must not only meet the requirements for technical replacement cells or batteries, but they must not explode or catch fire even after the 13-cell crush (compression) test and the 14-cell impact test.

If technician-replaceable or user-replaceable cells are to be used in a cell setup or battery pack, the 10.3 cell test and the 12 cell test shall also be performed on the cells and they shall not ignite or explode after the test. The section 10.3 test also requires that the battery meet the requirements of sections 5.1.1, 5.2.1 and the section 10 short-circuit test.

Table 5.1

Venting and leakage mass loss criteria

Mass of Cell or Battery Maximum Mass % Loss
Not more than 1 gram 0.5
More than 1 gram and not more than 5.0 gram 0.2
More than 5.0 gram 0.1

6. Samples of UL1642

Fully charged lithium polymer primary cells or lipo batteries and lithium polymer primary cells or lithium polymer batteries that have been partially or fully discharged, or both, shall be used for the tests described in Sections 10 to 19.

The number of samples to be used in each analysis for the technically replaceable primary cell or battery is given in Table 6.1. The number of samples to be used in each analysis for a user-replaceable primary cell or battery is given in Table 6.3. If a group of lithium polymer cells or lithium polymer batteries of different sizes but similar chemical composition are involved, samples of different sizes must be tested.

For the tests described in sections 10 to 19, fully charged lithium-ion secondary cells or lithium-ion batteries and lithium-ion secondary cells or lithium-ion batteries that have been conditioned by cyclic charging and discharging shall be used. The number of samples to be used in each test for a technically substitutable secondary cell or battery is given in Table 6.2.

The number of samples to be used in each test for a user-replaceable secondary cell or battery is given in Table 6.4. If a group of lithium-ion cells or lithium-ion batteries of different sizes and similar chemical composition are involved, samples of different sizes should be tested.

Prior to Section 17 testing, lithium-ion batteries shall be preconditioned as specified in 6.4 and 6.5. For the Section 17 heat test, two sets of five lithium-ion cell specimens shall be fully discharged (i.e., to the final voltage specified by the manufacturer).

The specimens are then placed in a test vessel and incubated for 1 to 4 hours (5 specimens at the upper temperature limit and 5 specimens at the lower temperature limit of the operating range) as specified in Table 6.3. Fully charged lithium-ion secondary cells or lithium-ion batteries and lithium-ion secondary cells or lithium-ion batteries that have been conditioned by cyclic charging and discharging shall be used for the tests described in Sections 10 to 20.

The number of samples to be used in each test for a technically substitutable secondary cell or battery is given in Table 6.2. The number of samples to be used in each test for a user-replaceable secondary cell or battery is given in Table 6.4. If a group of lithium-ion cells or lithium-ion batteries of different sizes and similar chemistries are involved, the selected sizes representing the range should be tested.

Table 6.1

Number of batteries to be used in each test for primary technician-replaceable batteries

 

Test

Conditioning of Batteries
Fresh One half discharged Complete discharged
Electrical Test
Short-Circuitb
at room temp. 5 5
at 60℃(140℉) 5 5
Abnormal Charge 5 5 5
Dischargec 5 5 5
Mechanical Test
Crush 5 5
Impact 5 5
Shock 5 5 5
Vibration 5 5 5
Environment Test
Heating 5 5
Temperature 5 5 5
Altitude Simuation 5 5 5

aOnly cells with a liquid cathode, such as thionyl chloride or sulfur dioxide, are conditioned by on-half discharge.

BFor series or parallel use, see 10.3

cFor series use, see 11B.2

 

Table 6.2

Number of batteries to be used in each test for secondary technician-replaceable batteries

Test Fresh Charge/Discharged Cycled
Electrical Test
Short-Circuita,c.
at room temp. 5 5
at 60℃(140℉) 5 5
Abnormal Chagre 5 5
Dischargeb 5 5
Mechanical Tests
Crushc 5 5
Impactc 5 5
Shock 5 5
Vibration 5 5
Enviromental Tests
Heating 5 5
Temperature Cycling 5 5
Altitude Simulation 5 5

aFor series or parallel use, see 10.3.

bFor series use, see 11B.2

cTest are to be conducted on samples in the fully charged condition.

 

Table 6.3

Number of batteries to be used in each test for primary user-replaceable batteries

 

Test

Conditioning of batteries
Fresh One halfa discharged Complete discharged
Electrical Tests
Short-Circuitb
at room temp. 5 5
at 60℃(140℉) 5 5
Abnormal Chagre 5 5 5
Dischargec 5 5 5
Mechanical Tests
Crush 5 5
Impact 5 5
Shock 5 5 5
Vibration 5 5 5
Enviromental Tests
Heating 5 5
Temperature Cycling 5 5 5
Altitude Simulation 5 5 5
User Replaceable Lithium Battery Tests
Flaming Particles 5
Projectile 5

aOnly cells with a liquid cathode, such as thionyl chloride or sulfur dioxide, are conditioned by one-half discharge.

BFor series or parallel use, see 10.3.

cFor series use, see 11B.2.

 

Table 6.4

Number of batteries to be used in each test for secondary user-replaceable batteries

Test Fresh Batteries conditioned by charge-discharg cycling
Electrical Tests
Short-Circuita,c.
at room temp. 5 5
at 60℃(140℉) 5 5
Abnormal Chagre 5 5
Discharge 5 5
Mechanical Tests
Crusha,c 5 5
Impactc 5 5
Shock 5 5
Vibration 5 5
Enviromental Tests
Heating 5 5
Temperature Cycling 5 5
Altitude Simulation 5 5
User Replaceable Lithium Battery Tests
Flaming Particles 5
Projectile 5

aFor series or parallel use, see 10.3.

aFor series use, see 11B.2.

cTests are to be conducted on samples in the fully charged condition.

7. Discharge Conditioning of LiPo Batteries

7.1 Primary lithium-ion batteries shall be fully discharged by connecting their terminals through resistors that provide the required level of discharge for 60 days. Final discharge is considered when the closed circuit voltage is reduced to less than 0.2 volts and the short circuit current to less than 1.0 milliampere. Lithium-ion batteries are discharged at room temperature. Lithium-ion cells with a liquid cathode, such as thionyl chloride or sulfur dioxide, shall also be conditioned by half discharge.

7.2 In the case of solid electrolyte batteries and other types of primary lithium-ion batteries that cannot be discharged within 60 days due to the small currents they produce genetically, longer operating times and higher temperature discharges may be used to obtain the desired level of discharge. To achieve the required discharge level as quickly as possible, the battery manufacturer’s recommended discharge procedures should be followed.

7.3 Secondary lithium-ion cells must be conditioned at 25°C (77°F). Li-ion cells are continuously cycled in accordance with the battery manufacturer’s specifications. Specifications shall be such that the full rated capacity of the lithium-ion cell is used and the number of total cycles shall be at least 25 percent of the life of the lithium-ion cell or continuous cycling shall be for 90 days, whichever is shorter. Cycling must be performed individually or in groups. Lithium-ion cells shall be recharged prior to testing as specified in Table 6.2 and Table 6.4.

8. Important Precautions for Test of UL1642

8.1 Some lithium batteries may explode when tested in accordance with Section 10-19 and personal protection should be provided against flying splinters, sudden release of heat from the force of the explosion, and hazards associated with explosion noise. The area to be tested should be well ventilated.

8.2 All persons participating in the test should not touch the exterior surface of the battery if the temperature of the battery enclosure is determined to exceed 90C during the tests in Sections 10, 13 and 17.

9. Temperature Measurements of UL1642

The area of the thermocouple wire for measurement should be no greater than 0.21mm2, greater than 0.05mm2, and used in conjunction with thermal potential measurement equipment.

When measuring, the thermocouple must be pressed against the surface of the battery case.

10. Short-Circuit Test of UL1642

10.1 The positive and negative terminals of each sample test cell shall be short-circuited by a copper wire having a resistance of less than 0.19 ohms. The battery shall be continuously discharged until it catches fire or explodes or until it is completely discharged and the temperature of the case has dropped to ambient temperature.

10.2 The test shall be performed at room temperature 60+2 °C and the battery shall be short-circuited at room temperature or 60±2 °C to achieve equilibrium stability with the environment.

10.3 Cells shall be tested individually unless the manufacturer specifies that series or parallel connection is required. For series or parallel applications an additional five sets of cells should be tested and the maximum number of cells used should be determined by the number of series/parallel connections used.

10.4 When a UL listed thermal or overcurrent protection device is installed, the battery shall be tested at full load with the protection device uncovered. Non-certified protective devices shall be shorted.

10.5 The battery sample shall be non-flammable and non-explosive and the temperature of the battery casing shall not exceed 150°C.

11. Abnormal Charging Test of UL1642

11.1 Batteries shall be tested after being discharged to the capacity specified by the manufacturer.

11.2 Each battery sample shall be subjected to a charging current 3 times the normal charging current specified by the manufacturer. The battery shall be connected to a direct current source. A specified charge current is achieved by connecting a resistor of a specified size and specification in series. The test time is calculated using the following formula:

tc = 2.5C/3Ic

Tc is the charging time (h); C is the capacity (Ah), Ic is the normal charging current specified by the manufacturer (A).

The minimum test time should be 48 h, but this does not mean that the initial charging current has to be maintained for 48 h.

11.3 If the battery is protected by a certified thermal or overcurrent protection device, the battery shall be tested at maximum load without tripping the protection device. Non-certified protection devices shall be short-circuited before testing.

11.4 The sample shall not ignite or explode.

12. Forced-Discharge Test of UL1642

12.1 This test is suitable for applications where several cells are combined, e.g. rechargeable batteries.

12.2 The fully discharged cell should be connected in series with a new cell of the same type and then subjected to a forced discharge. Number of new cells in series = maximum number of cells applied in series – 1. 5 cells tested at room temperature after full discharge.

12.3 When the fully discharged cells are connected in series with a new cell designed for a certain number of days, the resulting battery pack is tested for short circuits.

12.4 The positive and negative terminals are connected to Cu wires with a resistance of less than 0.1Ω and the cells are discharged until they catch fire or explode or the test is completed when the temperature of the battery enclosure drops back to near room temperature.

12.5 If there is already an approved thermal and overcurrent protection device that responds during the test, the test shall be performed at a maximum load that does not cause the protection device to respond, or at a short circuit, if there is no approved protection device.

12.6 The sample must be non-flammable and non-explosive.

13. Crush Test of UL1642

13.1 A 32 mm diameter hydraulic piston is used to apply a compressive force between two flat cell surfaces. Compression is continued until a pressure of 17.2 MPa is reached, applying a pressure of 13 KN and relaxing the pressure when the maximum pressure is reached.

13.2 The cylindrical or square cell is compressed so that the plane of the hydraulic unit is parallel to its longitudinal axis. The square cell shall also be rotated 90°C in the direction of the long axis, this is necessary to ensure that the wide and narrow sides can withstand compression. Each cell of the specimen is subjected to compression in only one direction and separate cells are used for each test.

13.3 Coin or button batteries shall be compressed in the in-plane direction.

13.4 Batteris shall not ignite or explode.

14. Impact Test of UL1642

14.1 The test is carried out with the sample cell on a flat surface, then a 15.8 mm diameter rod is placed in the center of the sample and a 9.1 kg weight is dropped on the sample from a height of 610 mm.

14.2 The cylindrical or square cell is struck so that its long axis is parallel to the plane and perpendicular to the curved surface of the 15.8 diameter rod placed in the center of the sample. The square cell shall be rotated 90 degrees in the direction of the long axis so that both the wide and narrow sides are impacted. Each cell of the specimen is only impacted in one direction. Separate specimens are used for each test.

14.3 The plane of the button cell shall be parallel to the plane at the center of which is the curved surface of the 15.8 mm rod.

14.4 The battery shall not catch fire and not explode.

15. Shock Test of UL1642

15.1 The cells are placed in a fixed fixture and each facet must be fixed. Each cell shall be subjected to three accelerations of equal magnitude and each cell shall be accelerated along three mutually perpendicular directions, unless the cell shape has only two directions, then each direction of vibration acceleration shall be perpendicular to the cell surface. The minimum average acceleration should be 75g (g stands for gravity acceleration) during the first 3 s. The acceleration at the moment of peak should be 125-175 g. The test shall be carried out at a temperature of 20±5℃.

15.2 The sample shall not ignite or explode and there shall be no leakage of the sample.

16. Vibration Test of UL1642

16.1 The cell is subjected to a simple amplitude of 0.8mm tuned vibration.

16.2 The vibration frequency varies at a rate of 1Hz/mim in the range of 10-55Hz and recovers back within 90-100mim. The cell vibrates along three mutually perpendicular directions, and for cells with only two axes, the cell should be tested along a direction perpendicular to each axis.

16.3 The sample must not catch fire, explode, or leak.

17. Heating Test of UL1642

17.1 The sample is heated in a natural convection or forced convection oven, and the oven temperature should be increased to 150℃ at a rate of 5±2℃/mim and maintained for 10min.

17.2 The sample cannot catch fire and does not explode.

18. Temperature Cycling Test of UL1642

18.1 The battery is placed in the test chamber, and then the following cycles are performed.

a) temperature rise to 70±3℃ within 30min, holding for 4h.

b) Cool down to 20±3℃ within 30min and hold for 2h.

c) temperature rise to 40±3℃ within 30min, insulation 4h.

d)Cool down to 20±3℃ within 30min.

e)Repeat the above cycle for 9 times.

F) 10 times after the cycle, the battery is placed for 7 days to be tested.

18.2 The sample should not catch fire, no explosion, no leakage.

19. Low Pressure (Altitude Simulation) Test of UL1642

19.1 The sample cell must be stored at an absolute pressure of 11.6Kpa (1.68psi) and a temperature of 20+3°C (68±5F) for 6 hours.

19.2 The sample cell must not explode or catch fire, especially the cell must not have perforations or leaks.

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