How to Properly Choose a Power Lithium Battery Product

Lithium-ion batteries, known as the “ultimate energy” and “green energy,” have been widely used in people’s production and daily lives since their introduction in the 1990s. From button batteries in electronic products, lithium batteries in mobile phones and digital cameras, to power storage batteries in electric vehicles, they have found applications in various fields. Compared to other types of batteries, lithium-ion batteries offer significant advantages in terms of size, weight, and performance.

Use Lithium Batteries within Reasonable Voltage and Capacity Ranges
Pursuing extremely large capacities and high voltages is an incorrect approach. First, everything goes through a process from simple to complex, and from difficult to easy. Just like flammable gases, ensuring the safety of a lighter is relatively easy, while ensuring the safety of a car’s fuel tank in a collision is much more challenging, and the issue of car fires or explosions in crashes has not been completely resolved. The more energy accumulated in a limited space, the harder it is to manage. Currently, Suzhou Xingheng can only guarantee the safety of battery combinations with a maximum of 48V 10Ah. Additionally, higher voltages and larger capacities increase the difficulty and failure rate of protection and balancing circuits. Therefore, Suzhou Xingheng does not advocate or support battery combinations exceeding 48V 10Ah.

Look for Safety Testing and Certification for Lithium Batteries
UL Certification
Today, most countries and regions worldwide require products related to safety, health, and environmental protection to obtain safety certification before entering the market. The UL mark has become one of the most famous safety certification marks in the world.

Testing Standards:

Casing
The lithium battery casing should have enough strength and rigidity to withstand external pressure without causing a fire. User-replaceable lithium batteries should have sufficient strength to avoid injury to users.

Electrolyte
User-replaceable batteries should not contain pressure vapor or toxic gases and liquids that could harm the eyes. Under normal laboratory conditions (23°C), if impacted, the leakage should not exceed 5ml.

Usage
Measures should be in place to avoid abnormal charging currents during use. The battery has an acceptable charging current (Ic). In abnormal conditions, protective measures should be implemented in the end product.

Leakage
Leakage or loss of mass standards: The maximum loss of mass of the battery cell or battery should not exceed:

1g: 0.5%
1-5g: 0.2%
5g: 0.1%

Mechanical Tests

Crushing: Apply a 13kN pressure (17.2 MPa) with a 32mm diameter hydraulic piston to the two flat surfaces of the battery. After reaching maximum pressure, release the pressure. The sample should not catch fire or explode.
Impact: Drop a 9.1kg weight from a height of 610mm onto a 15.8mm diameter rod placed at the center of the sample. The sample should not catch fire or explode.
Acceleration: Place the battery in a fixed fixture and apply acceleration in three perpendicular directions. The minimum average acceleration in the first 3ms should reach 75g, with peak acceleration between 125-175g. The sample should not catch fire, explode, or leak.
Vibration: Subject the battery to simple tuned vibration along three perpendicular directions with a frequency range of 10-55Hz, with a change rate of 1Hz/min. The sample should not catch fire, explode, or leak.
Thermal Shock: Heat the sample in a natural or forced convection oven, raising the temperature at a rate of 5±2°C/min to 150°C, and maintain for 10 minutes. The sample should not catch fire or explode.
Thermal Cycling Test: The battery undergoes the following cycles:
Heat up to 70±3°C in 30 minutes and hold for 4 hours.
Cool down to 20±3°C in 30 minutes and hold for 2 hours.
Heat up to 40±3°C in 30 minutes and hold for 4 hours.
Cool down to 20±3°C in 30 minutes.
Repeat for 9 cycles.
After 10 cycles, place the battery for 7 days for inspection. The sample should not catch fire, explode, or leak.
High Altitude Simulation: Store the battery at an absolute pressure of 11.6kPa (1.68psi) and 20±3°C for 6 hours. The sample should not catch fire or explode and should not have punctures or leaks.
Charge and Discharge Tests

Charge and Discharge Cycles: At 25°C, perform charge and discharge cycles until the capacity reaches 25% of the initial nominal capacity or after 90 days of continuous cycling. The sample should not exhibit any safety issues.
Short Circuit Test: Short-circuit the battery’s positive and negative terminals with copper wire (resistance less than 0.1Ω). The sample should not catch fire or explode, and the shell temperature should not exceed 150°C.
Abnormal Charging Test: After normal discharge, charge the battery at three times the normal charging current. The sample should not catch fire or explode.
Forced Discharge Test: Fully discharge the battery at room temperature and conduct a short-circuit test with a number of new cells connected in series. The sample should not catch fire or explode.
Overcharge: Charge the battery under constant current and voltage conditions, when the current reaches 100mA, continue charging at constant voltage for 48 hours.
Marking
The battery should be clearly marked with the manufacturer’s name, trademark, and model. A “Warning” label with a corresponding description is also required.

Extra Energy Certification
Extra Energy certification is a non-profit organization headquartered in Germany, focusing on providing neutral information about lightweight electric vehicles worldwide, and offering value-added services. It includes strict and rigorous lithium battery safety testing, which is recognized by most European customers.

Testing Standards:

Abnormal Charging:
At room temperature, empty battery, and factory assembly, remove the protection and management circuits. Charge the battery pack to 1.5 times its nominal voltage with 10A current. The sample should not catch fire or explode; the battery shell temperature should remain below 120°C.

Short Circuit:
At room temperature, using the factory charger, charge the battery to full and remove protection circuits. Short-circuit the battery’s positive and negative terminals. The sample should not catch fire or explode, and the battery shell temperature should stay below 120°C.

Heavy Object Crushing:
At room temperature, using the factory charger, charge the battery to full and remove protection circuits. Apply 10 tons of pressure with a steel roller of 15cm diameter. The sample should not catch fire or explode, and any released gases, solids, or liquids should be non-toxic.

CE Certification
In recent years, the use of the CE mark on products sold in the European Economic Area (EEA) has been increasing. The CE mark indicates that the product meets a series of European directives related to safety, health, environmental protection, and consumer protection.