ASOL 403040 Lithium Polymer Battery — Ultra-compact Li-Po soft pack engineered for miniaturized consumer electronics. At just 4.1mm thin with a 43×30.5mm footprint, this battery integrates seamlessly into sleek wearable and IoT devices. It delivers a reliable 400mAh capacity with 500+ cycle life, making it an ideal long-lasting power solution for TWS earbuds, smartwatches, fitness trackers, BLE beacons, and other space-constrained electronics.
🔋 Why Lithium Polymer vs Cylindrical Cells?
Unlike traditional cylindrical batteries (e.g. 18650), lithium polymer soft-pack cells offer decisive advantages for compact consumer devices:
- 📏 Thinner Profile — As low as 3mm thickness vs minimum 18mm for 18650
- 🔄 Flexible Shape — Adapts to custom enclosures, curved designs, and irregular cavities
- 🪶 Lighter Weight — Up to 30% lighter than equivalent-capacity cylindrical cells
- 🔒 No Pressure Vents — Safer for ultra-compact devices with limited or no venting
- ⚡ Higher Energy Density — Maximizes capacity in minimal physical space
- 🔧 OEM-Friendly Customization — Tabs, wires, connectors, and form factor tailored to your product
Key Features
- 🔋 Mini Size — 4.1×30.5×43mm fits ultra-compact device enclosures
- ⚡ 400mAh Capacity — 1.48Wh energy in a tiny soft-pack form factor
- 📐 Ultra-Slim 4.1mm — Enables sleek, lightweight product industrial design
- 📦 Soft Pack Design — Aluminum-laminated polymer construction, lightweight and flexible
- 🔄 500+ Cycles — Extended service life with minimal capacity fade
- 🔒 Multi-Certified — UL, CB, KC, PSE, CQC, UN38.3 — market-ready worldwide
- 🌡️ Wide Temp Range — Charge: 0~45°C / Discharge: -20~60°C
- ⚙️ OEM/ODM Support — Available with tabs, wires, connectors, or fully custom form
- 🛡️ UN38.3 Certified — Safe for air transport; full documentation available
Specifications
| Parameter | Value |
|---|---|
| Model | 403040 |
| Cell Type | Lithium Polymer (Li-Po) Soft Pack |
| Nominal Voltage | 3.7V |
| Nominal Capacity | 400mAh |
| Energy | 1.48Wh |
| Thickness (T) | 4.1mm (Max) |
| Width (W) | 30.5mm (Max) |
| Length (H) | 43mm (Max) |
| Configuration | 1S1P |
| Impedance | ≤150mΩ |
| Charge Voltage | 4.2V |
| Standard Charge Current | 80mA (0.2C) |
| Max Charge Current | 400mA (1C) |
| Standard Discharge Current | 80mA (0.2C) |
| Max Discharge Current | 400mA (1C, continuous) |
| Discharge Cut-off | 2.5V |
| Charge Temp | 0~45°C |
| Discharge Temp | -20~60°C |
| Storage Temperature | -10~35°C |
| Cycle Life | 500+ cycles (100% DOD, 1C, 25°C) |
| Weight | Approx. 9g |
| Certifications | UL, CB, KC, PSE, CQC, UN38.3 |
Applications
🎧 Audio & Personal Sound
TWS earbuds (left/right + charging case), Bluetooth headset ear hooks, bone conduction headphones, wireless headset gaming headsets, neckband earphones, mini portable voice recorders
⌚ Wearables & Fitness
Smart watchbands, fitness trackers, sports smart rings, sleep monitoring bands, wearable oximeters, smart jump rope counters, calorie-tracking wristbands
📡 IoT & Smart Home
BLE beacons & iBeacons, environmental sensors (temp/humidity), door/window sensors, smart plug adapters, voice assistant remotes, gesture control devices, smart key trackers
✏️ Digital Writing & Tools
Smart stylus pens (Apple Pencil style), digital notepad pens, smart highlighters, electronic signature pads, smart label makers, digital measuring tools
🏥 Health & Portable Medical
Wearable pulse oximeters, digital thermometers, portable blood pressure monitors, Bluetooth glucometers, smart pill organizers, handheld diagnostic devices
Why Choose ASOL Li-Po Batteries?
ASOL Battery combines cutting-edge lithium polymer cell engineering with rigorous quality assurance across every production batch. Our ultra-compact Li-Po batteries are purpose-built for miniature consumer electronics — devices where every millimeter of thickness and every gram of weight directly impacts user experience. We work directly with product designers and engineers to ensure our battery form factor integrates seamlessly into their mechanical enclosures.
With comprehensive global certifications — UL, CB, KC, PSE, CQC, UN38.3 — ASOL batteries are pre-cleared for major markets including North America, Europe, Japan, South Korea, and China. Our dedicated OEM/ODM team supports custom tabs, wiring harnesses, and connector integration, so you receive a battery ready to drop into production with minimal engineering overhead.
Wholesale Pricing
| Quantity | Unit Price | Savings |
|---|---|---|
| 100–499 pcs | Contact us | — |
| 500–999 pcs | Contact us | 8% off |
| 1,000–4,999 pcs | Contact us | 15% off |
| 5,000+ pcs | Contact us | 20%+ off |
📌 Sample orders and custom specifications welcome. Full certification documentation provided.
Contact Us
| Channel | Information |
|---|---|
| info@asol-battery.com | |
| +86 157 7985 8703 | |
| 🌐 Website | www.asol-battery.com |
| ⏰ Response Time | Within 24 hours on working days |
