After completing over 6,000 custom lithium battery pack projects, we found that clients often have specific questions. In this article, we will delve into the essential questions and answers regarding the designing and producing lithium-ion battery packs.
What Are The Key Factors To Consider When Choosing A Custom Lithium-ion Battery Pack?
When selecting a custom lithium-ion battery pack, it is essential to consider several key factors.
Firstly, densité énergétique plays a vital role, as customers often look for lithium-ion batteries for portable applications, desiring high energy capacity in a compact and lightweight design.
Moreover, the discharge rates should be taken into account. There are two main types of lithium-ion cells – energy cells and power cells. Energy cells offer high energy density but lower current delivery, resulting in longer runtime, while power cells provide rapid high current output with lower energy density.
Cycle life is another critical aspect to consider. Lithium-ion phosphate cells, despite potentially being heavier, can deliver over 3,000 cycles, surpassing the 500-600 cycles of other types.
Safety is paramount for all lithium-ion batteries, with lithium-ion phosphate cells known for their enhanced robustness in terms of safety features.
Furthermore, temperature tolerance is an important consideration. Although lithium batteries were previously limited in high-temperature applications, advancements now enable their use in various settings with elevated temperatures.
How Can Thermal Management Be Integrated Into A Custom Lithium Pack?
A larger enclosure often dissipates heat better, and we sometimes add heat spreaders in packs to manage excess heat.
Tesla’s approach to active cooling sets a high standard in the industry, using liquid circulation around individual cells to maintain uniform temperatures and eliminate thermal gradients. This advanced system ensures internal cells match the temperature of external cells, even enabling preheating on cold days for improved efficiency and longevity.
If budget constraints limit cooling options, leveraging temperature sensors can be a cost-effective solution. These sensors can monitor temperature variations and adjust the device’s operation accordingly, such as throttling the processor or adjusting motor speed to prevent overheating.
Additionally, implementing warning systems within the battery pack can help alert users to potential temperature issues and take preventive measures effectively.
What Less Common Safety Features Should Be Included In A Custom Lithium Battery?
Second-tier and third-tier safety features often go unnoticed, but one important aspect is équilibrage cellulaire.
Many people see it as a cycle life feature, similar to evenly filling an ice cube tray to ensure all cells maintain equal levels. This balance extends the pack’s lifespan and prevents individual cells from falling too low or rising too high, which can trigger safety circuits and reduce runtime perception.
Additionally, if safety circuits malfunction, continuous low or high excursions can lead to dendrite growth or issues with separating materials, potentially causing internal shorts. Thus, cell balancing is indeed a safety feature.
Other considerations include encapsulating batteries with effective pressure relief valves. It can help mitigate the risk of overpressure within the battery pack, especially during rapid charging or in case of a malfunction.
Finally, using flame-retardant materials rated for high temperatures ensures that composants don’t ignite during failure situations. These lesser-known safety features play a crucial role in battery performance and reliability.
Do Most End-product Standards Require Batteries To Meet Specific Standards?
Yes, most end-product standards mandate that batteries meet specific safety, performance, and quality criteria to ensure consumer safety and product reliability. Regulatory bodies enforce these standards to mitigate risks like fire hazards, emballement thermique, and environmental impact.
Key standards include:
- ET 38.3: Covers testing requirements for the safe transport of lithium batteries.
- IEC 62133: Specifies safety requirements for lithium ion batteries in portable electronic devices.
- IEC 62619: Focuses on the safety of secondary lithium-ion cells and batteries in industrial applications.
- UL1642 and UL 2054: Safety standards for lithium batteries in household and industrial use.
- CE Marking: Indicates conformity with EU safety standards.
Compliance is necessary to prevent recalls, legal liabilities, and damage to brand reputation; manufacturers must adhere to these standards to deliver safe battery-powered products.
Do You Have Recommendations For Finding Cells Online For In-house Manufacturing? Is It As Simple As Using Google To Find Options That Meet My Requirements?
While Google can be a starting point, here are recommendations for finding reliable cell suppliers:
- Partner with reputable suppliers known for quality battery cells and reliable support.
- Confirm clear specifications, including voltage, capacity, energy density, cycle life, size, weight, and safety features to narrow your search.
- Ensure compatibility with your system by considering mechanical fit, electrical connections, and charging/discharging protocols to avoid integration issues during manufacturing.
- Choose cells that meet recognized industry standards like UL or IEC for safety and performance; review product datasheets or test reports from the supplier.
- Consult industry experts, engineers, or consultants experienced in sourcing battery cells for manufacturing. They can guide you in selecting the right cells for your specific needs.
- Evaluate shipping logistics regarding options, lead times, costs, and delivery requirements.
How Do You Determine A Product’s Cycle Life?
Generally, determining a battery’s cycle life involves several methods:
- Manufacturer Specifications: Check the manufacturer’s estimated cycle life, which is often based on standardized testing. However, these values typically reflect low steady-state currents.
- Accelerated Aging Tests: Conduct tests in controlled conditions by repeatedly charging and discharging the battery while monitoring performance and capacity decline. This method estimates how many cycles the battery can endure before reaching a specific capacity threshold (e. g., 80% of original capacity).
- Past Data and Experience: Historical data on similar batteries can provide insights into expected cycle life through industry research and case studies, though this method offers rough estimations.
- Battery Chemistry and Design: Different chemistries have varying cycle life characteristics; understanding these along with design factors like electrode materials can give rough estimates of performance.
- Operational Conditions: Factors such as discharge rate, depth of discharge (DOD), charging protocols, and environmental conditions significantly influence cycle life.
While these methods provide rough estimates, actual testing tailored to specific conditions is the most reliable way to determine a battery’s cycle life, particularly for outdoor products subject to temperature extremes.
