3.7V 4000mAh LiPO Battery Pack for Compact Electronic Devices
Medical devices, smart toys, IoT systems, and wireless Bluetooth equipment are just a few examples of small electronics that need a power solution that matches high energy density, stable performance, strict safety requirements, and limited installation space. This project showcases how CM Batteries supported a client needing a slim yet durable 3.7V Li-polymer battery that could withstand variable operating temperatures and ensure reliable performance throughout product life.

Key features:
- Custom Slim Form Factor. Designed at 8.8 × 55.5 × 150 mm, the pack was engineered to fit seamlessly inside the client’s device structure without sacrificing capacity.
- Optimized for Variable Temperature Environments.The battery operates within charge temperature range of 0°C to 45°C and discharge temperature range of -20°C to 60°C. This ensures stable operation for outdoor, winter-use, or high-temperature scenarios.
- Enhanced Energy Density & Lightweight Design. With only 63g, the battery maintains high capacity while improving user comfort and reducing system weight., ensuring reliability in consumer and medical environments.
- Safe and Stable Cycle Life. Engineered for 300 cycles with ≥80% capacity retention, ensuring long-term reliability for consumer and medical applications.
| No. | Item | Parameter | Remark |
|---|---|---|---|
| 1 | Nominal Voltage | 3.7V | 3.7V/Cell |
| 2 | Nominal Capacity | 4Ah | @0.2C |
| 3 | Minimum Capacity | 3.8Ah | / |
| 4 | Shipment Voltage | / | / |
| 5 | Initial Internal Impedance | ≤200mΩ | AC 1KHZ |
| 6 | Standard Charge Voltage | 4.2V | 4.2V/Cell |
| 7 | Standard Charge Current | 0.8A | @0.2C |
| 8 | Max. Charge Current | 0.8A | |
| 9 | Standard Discharge Current | 0.8A | @0.2C |
| 10 | Max. Discharge Current | 1.6A | / |
| 11 | Burst Discharge Current | 5-9 | ≤5ms |
| 12 | Discharge Cut-off Voltage | 2.4 | 2.4V/Cell |
| 13 | Cycle Life | ≥300 cycles | Retention: ≥80% |
| 14 | Charge Temperature | 0°C~45°C | Standard Charge |
| 15 | Discharge Temperature | -20°C ~60°C | Standard Discharge |
| 16 | Storage Temperature | 0°C~ 35°C | ≤3 Months |
| 0°C ~ 25°C | ≤1 Year | ||
| 17 | Weight | About 0.063 | kg |
3.7V 4000mAh LiPO Battery Pack FAQs
If my device has very limited internal space, can this 3.7V 4000mAh Li-poly battery be adjusted without affecting performance?
Yes. For projects where internal structural space is extremely constrained—such as slim medical handhelds, compact IoT terminals, or elongated toy enclosures—we can reconfigure the cell dimensions while maintaining the required 4000mAh capacity.
Can the operating temperature range be modified for harsher environments?
The discharge temperature range can be extended for specific scenarios, such as outdoor IoT devices or winter-use consumer products.
Can the capacity be increased without significantly raising the total weight?
Capacity can be enhanced through material optimization or structural adjustment while maintaining a lightweight design profile.
Can the discharge capability be modified to meet higher peak-load requirements?
The discharge rate (e.g., 1.6A Max) can be reconfigured according to motor load or pulse-power needs, with thermal and cycle-life assessments aligned accordingly.
Do you support safety certifications for medical and IoT industries?
We can assist with IEC62133, UN38.3, MSDS, transportation reports, and other compliance documentation depending on project needs.
Tailored Customization
Our design team can create custom battery designs for just about any device or machine.
Timely Delivery
Our efficient production and distribution process gets your product delivered in a timely manner.
Quality Guarantee
We stand by our products and guarantee you’ll be happy with your purchase.

