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Pack Design Guideline for Lithium Battery

If a customer’s battery pack cannot meet Pack Design Guideline, we cannot take responsibility for a quality issue about a battery cell.

1. Electrical design

1.1   Charge

1.1.1   Stop charging the battery if charging isn’t completed within the specified time.

1.1.2   The battery can be used within the following temperature ranges. Don’t exceed these ranges.

Charge temperature ranges : 0℃ ~ 45℃

1.1.3   Charge current must be controlled by specified value in Cell specification.

1.1.4   Cut-off Voltage of charging must be under 4.2V.

1.1.5   Charger must stop charging battery by detecting either charging time or current specified in Cell’s specificaiton.

1.1.6   Recharge Voltage must be at least 0.1V lower than Max charging Voltage.

1.1.7   Do not charge the battery under 1.0V Voltage.

1.1.8   Voltage range of the battery for pre-charge mode is 1.0 ~ 3.0V with a charging current of 0.1 ~0.5C.

1.2 Discharge

1.2.1   Discharge current must be controlled by specified value in Cell’s specification.

1.2.2   Cut-off Voltage of discharging must be over 5V.

1.2.3   The battery can be used within the following temperature ranges. Don’t exceed these ranges.

Discharge temperature ranges : -20℃ ~ 60℃

1.3 Storage

Store the battery at low temperature (below 60℃, 20℃ is recommended), low humidity(below 65%), no dust and no corrosive gas atmosphere.

1.4 Design of positioning the battery pack in application and charger

To prevent the deterioration of the battery performance caused by heat, battery shall be positioned away from the area where heat is generated in the application and the charger.

1.5 Safety Device

Be sure adopting proper safe device such as PTC specified type or model in Cell Specification. If you intend to adopt different safety device which is not specified in Cell Specification, please contact Onex Limited to investigate any potential safety problem. Be sure designing 2nd protective devices such as PTC & PCM at the same time to protect Cell just in case one protective device is fault.

2. Design of System

2.1   Connection between the cell and thebattery

2.1.1   The cell should not be soldered directly with other cells. Namely, the cell should be welded with leads on its terminal and then be soldered with wire or leads to solder.

2.1.2   Otherwise, it may cause damage of component, such as separator and insulator, by heat generation.

2.2   Positioning the battery in the System

2.2.1   The battery should be positioned as possible as far from heat sources and high temperature components.

2.2.2   Otherwise, it may cause loss of characteristics.

2.2.3   The recommended spacing between the cells is more than 1 mm.

2.3  Mechanical shock protection of the battery

2.3.1   The battery should be equipped with appropriate shock absorbers in the pack in order to minimize shock, which can damage the cells.

2.3.2    Otherwise, it may cause shape distortion, leakage, heat generation and/or rupture and/or open circuit.

2.3.3    Ultrasonic should not be used when manufacturing battery packs as it can damage the connection between component parts.

2.4  Short-circuit protection of the battery

2.4.1    The battery is equipped with an insulating sleeve to protect short-circuit which may occur during transportation, battery assembly and /or system operation.

2.4.2    If the battery sleeve is damaged by some causes such as outside impact, it may cause short-circuit with some wiring inside the battery.

2.5  Connection between the battery and charger/system

2.5.1   The battery should be designed to be connected only to the specified charger and system.

2.5.2    A reverse connection of the battery, even in the specified system, should be avoided by employing special battery design such as a special terminals.

2.6  Pack design

2.6.1    The current consumption of the battery pack should be under 10uA after shut down.

2.6.2    Cell voltage monitoring system.

The system (charger or pack) should be equipped with a device to monitor each voltage of cell block to avoid cell imbalance which can cause damage to the cells.

2.6.3    The battery pack or system should have warning system such as over temperature, over voltage, over current, and so on.

2.6.4    Mechanical design

ItemPortable ITPower-ToolMedicalE-BikeE-ScooterEV/LEVESS/UPS
□ Need partitions (separator) between BMS and a Cell
□ Need to check if the pack is designed to be able to avoid thermal runaway (1KWh↑)
□ Need to analyze the battery pack's thermal distribution and its effect on the pack's life cycle
□ Need to use a non flammable (VO level) case
□ Need to apply improved material (Steel) to the case
□ Need to analyze the battery pack's structure, system, installation status and use environment