Introduction
The 3.7V lithium polymer (Li-Po) battery is one of the most widely used rechargeable power sources in modern electronics. From wearable devices and TWS earbuds to medical sensors and IoT products, the 3.7V Li-Po cell offers the ideal balance of energy density, form factor flexibility, and safety.
At A&S Power, we specialize in manufacturing custom 3.7V lithium polymer batteries for OEM buyers worldwide. Whether you need a standard 120mAh cell for a smart ring or a high-capacity 10,000mAh pack for a portable device, we deliver tailored solutions that meet your exact specifications.
For a complete overview of our custom battery capabilities, check out our full guide: Custom Lithium Polymer Battery – OEM/ODM Solutions for IoT, Wearables & Medical Devices .
What is a 3.7V Li-Polymer Battery?
A 3.7V lithium polymer battery is a rechargeable power source that uses a gel-like polymer electrolyte instead of the liquid electrolyte found in traditional cylindrical cells. This design allows for ultra-thin, lightweight, and flexible form factors – making it the ideal choice for compact, space-constrained devices.
Key characteristics of a 3.7V Li-Po battery:
| Characteristic | Description |
|---|---|
| Nominal Voltage | 3.7V (standard single-cell configuration) |
| Chemistry | Lithium polymer (LiCoO₂, NMC, or LFP variants) |
| Form Factor | Flexible pouch – can be shaped to fit any enclosure |
| Thickness | As low as 3.0mm |
| Capacity Range | 20mAh to 10,000mAh+ |
| Cycle Life | 300–500+ cycles to 80% capacity |
| Safety | Built-in PCM protection (overcharge, over-discharge, short-circuit) |
| Certifications | UL, CE, RoHS, UN38.3, IEC62133 |
Why 3.7V is the Industry Standard
The 3.7V nominal voltage is the standard for single-cell lithium polymer batteries because:
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Compatibility: Most consumer electronics and IoT devices are designed to operate within the 3.0V – 4.2V range
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Energy Density: 3.7V cells offer the optimal balance of capacity and physical size
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Safety: Single-cell configurations require simpler protection circuits, reducing cost and complexity
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Global Adoption: 3.7V is universally recognized – engineers and procurement teams worldwide spec this voltage
Key Applications for 3.7V Li-Polymer Batteries
Our 3.7V Li-Po cells are deployed across multiple industries:
1. Wearable Devices
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Smartwatches and fitness trackers
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Smart glasses and AR/VR headsets
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Smart rings and jewelry
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Health monitoring patches
2. TWS Earbuds and Audio
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True wireless stereo earbuds
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Bluetooth headphones
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Portable speakers
3. Medical Devices
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Continuous glucose monitors (CGM)
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ECG and heart rate monitors
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Drug delivery systems (insulin pumps, inhalers)
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Portable diagnostic equipment
4. IoT Sensors
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Environmental monitors (temperature, humidity, air quality)
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Asset trackers and GPS locators
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Smart home sensors (motion, door, window)
5. Consumer Electronics
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Wireless keyboards and mice
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Stylus pens and remote controls
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Portable chargers and power banks
Technical Specifications – What OEM Buyers Need to Know
When sourcing a 3.7V Li-Polymer battery, these are the key parameters to define:
| Parameter | Typical Range | Why It Matters |
|---|---|---|
| Capacity (mAh) | 20 – 10,000+ | Determines device runtime – higher capacity = longer usage |
| Dimensions (mm) | Custom (thickness from 3.0mm) | Must fit within your device enclosure |
| Discharge Rate (C) | 0.5C – 3C | Higher discharge rates needed for high-power devices |
| Operating Temperature | 0°C – 45°C (charge), -20°C – 60°C (discharge) | Must match your device’s operating environment |
| Cycle Life | 300 – 500+ cycles | Affects device longevity and warranty costs |
| BMS Communication | I²C, SMBus, CAN, HDQ | Required for smart devices that report battery status |
Customization Options for 3.7V Li-Polymer Batteries
As a custom lithium polymer battery manufacturer, A&S Power offers extensive customization to match your product’s unique requirements:
| Customization Area | Options |
|---|---|
| Capacity | From 20mAh to 10,000mAh+ |
| Dimensions | Custom thickness, length, and width |
| Shape | Rectangular, curved, stepped, or ultra-thin |
| BMS | Overcharge, over-discharge, short-circuit, overcurrent, temperature protection |
| Communication | I²C, SMBus, CAN bus, HDQ protocols |
| Terminals | Wire leads, JST, Molex, or custom connectors |
| Labeling | OEM branding with your logo and product specifications |
| Packaging | Industrial or retail-ready packaging |
| Certifications | UL, CE, RoHS, UN38.3, IEC62133 |
Safety Certifications – Critical for OEM Buyers
Every 3.7V Li-Polymer battery we manufacture meets international safety standards:
| Certification | What It Means for Your Product |
|---|---|
| UN38.3 | Safe air and sea transport – mandatory for global shipping |
| UL 1642 / 2054 | Safety tested for electrical, mechanical, and fire hazards – essential for North American markets |
| CE | Required for products sold in the EU |
| RoHS | Free from restricted hazardous substances – required globally |
| IEC62133 | International safety standard for portable rechargeable cells |
| ISO9001 / ISO14001 | Quality management and environmental systems – proven consistency and sustainability |
We provide full compliance documentation with every order – saving you time and reducing your regulatory burden.
Why Choose A&S Power for Your 3.7V Li-Polymer Battery Needs
There are many battery suppliers out there. Here is what sets A&S Power apart:
✅ True Customization
We design batteries to your exact dimensions, capacity, voltage, and connector requirements. No off-the-shelf compromises – we engineer the battery to fit your device.
✅ Engineering Support
Our team provides design reviews, thermal modeling, and BMS customization to ensure seamless integration into your product.
✅ Direct Factory Pricing
As a factory-direct manufacturer, we offer competitive pricing without sacrificing quality. No middlemen, no markups.
✅ Rigorous Quality Control
100% final functional testing and visual inspection on every battery. Batch-level traceability for full accountability.
✅ Full Compliance Documentation
UL, CE, RoHS, UN38.3, and IEC62133 certifications provided with every order.
✅ Global Shipping
UN38.3 certified for safe air and sea transport to customers worldwide.
Frequently Asked Questions (FAQ)
1. What is the typical cycle life of a 3.7V Li-Polymer battery?
Under standard conditions (0.5C charge/discharge, 25°C), our cells deliver 300–500 cycles to 80% capacity. With careful design, we can extend this to 700+ cycles.
2. Can I customize the dimensions of a 3.7V Li-Polymer battery?
Yes. We can manufacture batteries in virtually any shape and size – thickness as low as 3.0mm, and any length/width you require.
3. What is the minimum order quantity (MOQ)?
MOQ depends on the cell size and complexity. For standard pouch cells, MOQ starts at 1,000–3,000 units. For fully custom designs, we can work with lower quantities for prototyping.
4. Do you provide UL, CE, RoHS, and UN38.3 certifications?
Yes. We provide full compliance documentation with every order.
5. What is the difference between a 3.7V Li-Polymer and a 3.7V Li-Ion battery?
Li-Polymer batteries use a gel-like electrolyte and flexible pouch, allowing for ultra-thin and custom shapes. Li-Ion batteries typically use liquid electrolyte in rigid cylindrical or prismatic casings. Li-Polymer offers greater design flexibility and is generally safer.
6. Can you include custom connectors or BMS communication?
Yes. We support all standard connector types (wire leads, JST, Molex, Anderson) and offer BMS with I²C, SMBus, CAN, and HDQ protocols.
7. How long does sample development take?
Typical sample lead time is 2-4 weeks from specification finalization. Mass production takes 4-6 weeks after sample approval.
8. Do you ship to Europe, North America, and Australia?
Yes. We ship globally with full UN38.3 certification. We have customers across North America, Europe, Asia, and Australia.
Get a Quote for Your 3.7V Li-Polymer Battery Project
Ready to power your device with a custom 3.7V Li-Polymer battery? Contact A&S Power today.
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We provide full compliance documentation and engineering support with every order – so you can focus on your product, not battery sourcing.
Dongguan A&S Power Technology Co., Limited.
Building 1, No. 2, Keji 9th Road, Songshan Lake, Dongguan, Guangdong, China
📞 +86 137 1383 1631 | ✉ info@enerbe.net