Feature Battery

3.87V 1300mAh Lithium ion Battery 703440

Model: 703440 SKU: UFX0869-09

Engineered with a 3.87V nominal voltage, 4.45V charging voltage,this high-voltage lithium-ion battery delivers more usable energy than standard 3.7V cells.

Higher Nominal Voltage: 3.87V design for increased energy output and longer runtime.
Optimized 1300mAh Capacity: Balanced performance for demanding portable electronics.
Compact 703440 Size: Ideal for slim, space-constrained device designs.
Custom Battery Manufacturer: Ufine Battery provides tailor-made LiPo batteries with custom size, voltage, and capacity.

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Product Details
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FAQs

3.87V High-Voltage Design for More Power

A higher nominal voltage means more usable energy in the same size. This 3.87V battery is designed to outperform standard 3.7V cells while keeping your device compact.

Test Curves of 3.87v Cell

Take a closer look at the battery test curves—see the stability and performance you can trust for all your power needs!

Cycle Life
Self-Discharge
Discharge Rate
Temp Performance

Long-Lasting Power

This battery is a long-lasting powerhouse, retaining over 95% of its initial capacity even after 600 charge-discharge cycles. This outstanding longevity ensures a reliable and consistent performance, making it the perfect choice for devices that require extended use and durability.

Incredible Charge Retention

With an incredibly low self-discharge rate, this battery holds its charge exceptionally well. After a full year of storage, its voltage only shows a minimal drop from 4.15V to 4.05V, keeping your device ready to go even after long periods of inactivity.

Learn More About Discharge Rate 

Discharge Characteristics

Experience stable and reliable power delivery. The battery maintains an operating voltage above 3.4V for over 80% of its discharge cycle, ensuring consistent performance. It also delivers high capacity, retaining over 90% even at a high 5.0C discharge rate.

Extreme Temperature Performance

This battery is built for a wide range of climates. It offers consistent, high-capacity performance from 25°C to 60°C. Even in freezing conditions, it remains reliable, providing approximately 65% of its capacity at a frigid -30°C.

Unlock Longer Runtime with 4.45V Charging

Thanks to a 4.45V charging voltage, this battery stores more energy and keeps devices running longer between charges.

4.45V high-voltage charging design
More usable capacity per cycle
Longer operating time without increasing battery size

unlock longer runtime with 4.45v charging

IR < 70mΩ, Stable Power You Can Rely On

Low internal resistance helps reduce heat and power loss, keeping your device running smoothly.

1300mAh High Capacity, Compact Design

This 1300mAh battery fits into a slim 703440 form factor, making it easy to integrate into space-limited products.

1300mAh capacity in a compact size
Dimensions: 7 × 34 × 42 mm (max)
Perfect for lightweight and slim device designs
Discharge temperature: -20°C to 60°C
Charge temperature: 0°C to 45°C

Why Choose Ufine Battery

Ufine Battery (Direct Factory)

Direct manufacturer with full production control, ensuring consistent quality for every 18650 battery pack
Volume-based pricing with competitive factory cost
Supports custom battery pack size, PCM/BMS, connectors, cables, and configurations
Flexible MOQ, suitable for prototypes and small pilot runs
17 years of lithium battery manufacturing experience; provides technical drawings, pack design, and engineering guidance
Complete reports available: MSDS, UN38.3, CE, RoHS, etc.
Stable production with predictable lead time, ideal for OEM/ODM projects
Professional after-sales service with quick response for B2B clients

Design Your Battery Now

Ordinary Channels / Traders / Small Workshops

Often resell from unknown factories; inconsistent quality and higher failure risk
Middleman markups lead to unstable or higher pricing
Limited or no customization; mostly standard products only
High MOQ, difficult for new projects to start
Little to no technical support; only sells finished goods
Certifications often missing or incomplete, causing delays in shipping or customs
Lead time uncertain; stock availability unstable
Limited support; difficult to handle quality claims

Battery Specification

1. Mechanical Characteristics

Cell 703440 PCM Yes

NTC No Weight appr. 19g

Configuration 1S1P

2. Electrical Specification

Capacity	1300mAh	Nominal Voltage	3.87V
Energy	5.031Wh	Internal Resistance	less than 70mΩ
Max. Charge Voltage	4.45V	Discharge Cut Off	2.75V
Max. Charge Current	650mA	Max. Discharge Current	650mA
Standard Charge Current	260mA	Standard Discharge Current	260mA
Charging Temperature	0℃ to 45℃	Discharging Temperature	-20℃ to 60℃
Storage Temp. Range	1 year at -20℃ to +30℃ 3 mos. at -20℃ to +45℃ 1 mo. at -20℃ to +60℃	Cycle life	100 cycles ≥92% 300 cycles ≥88% 500 cycles ≥80%

3. Cell protection

Overcharge Detection	4.45 ±25mV (1000 to 1600msec delay, release 4.2V ±50mV)	Overdischarge Detection	2.8V ±50mV (115 to 175msec. delay, release 3.0V ±50mV)
Overcurrent Detection	5A to 9A (9 to 15msec. delay)	Short protection	Yes

Download Product Datasheet

Choosing a lithium battery is not about capacity alone. For engineers and product teams, the real questions are voltage behavior, charge limits, lifecycle trade-offs, and customization feasibility. This page answers those questions directly.

Part 1. Why 3.87V Nominal Voltage Matters (Compared to 3.7V)

A 3.87V nominal voltage battery delivers higher usable energy within the same physical size than a standard 3.7V cell.

More runtime without increasing battery size
Higher system voltage headroom for modern ICs
Better performance in space-constrained designs

For the 703440 size, moving from 3.7V to 3.87V nominal voltage allows designers to extract more energy without redesigning the enclosure.

Part 2. Understanding the 4.45V Charging Voltage (And Why It’s a Concern)

This battery is designed to be charged up to 4.45V, enabling higher energy density—but it requires proper charge control.

Charging to 4.45V increases capacity compared to 4.2V / 4.35V systems
Requires a high-voltage compatible charger IC
Proper protection circuitry is critical for safety and cycle life

Ufine Battery integrates high-voltage chemistry with stable electrode materials to support 4.45V charging while maintaining reliability.

Part 3. Is High Voltage Worth the Trade-Off?

Yes—when designed correctly.

Factor	Standard Li-ion (4.2V)	High Voltage Li-ion (4.45V)
Energy density	Lower	Higher
Runtime	Shorter	Longer
Charger requirement	Standard	HV-compatible
Design complexity	Lower	Moderate

For devices like wearables, medical electronics, smart sensors, and compact consumer products, the benefits often outweigh the added charger requirements.

Part 4. Real Capacity: What Does 1300mAh Actually Mean?

1300mAh is the rated nominal capacity under controlled test conditions, not a marketing peak value.

Discharge current
Cut-off voltage
Operating temperature
Load profile

Ufine Battery provides capacity testing under customer-specified conditions, not just standard lab specs.

Estimate battery runtime using an online calculator:

Battery Run Time

Capacity (mAh)

Discharge Current (mA)

Utilization Rate (%)

Calculate Now

Reset

Enter the values above

Part 5. Battery Size 703440: Is It Right for Your Design?

703440 typically refers to:

Approx. 7.0 mm thickness
34 mm width
40 mm length

This format is commonly selected when PCB layout is already fixed, thickness must stay under 8 mm, and a single-cell solution is preferred over parallel cells.

Part 6. Can This Battery Be Customized?

Yes. Ufine Battery offers deep customization, not just label changes.

Charging voltage (4.35V / 4.4V / 4.45V)
Capacity tuning
PCM / protection circuit design
Connector type and cable length
Cell thickness or footprint adjustment
Branding and OEM packaging

This allows you to match the battery to your system, not redesign your system around the battery.

Part 7. Typical Applications for 3.87V High-Voltage 703440 Cells

This battery is often evaluated for:

Wearable electronics
Portable medical devices
Smart sensors and IoT modules
Compact consumer electronics
Custom OEM devices requiring long runtime

If your product is energy-limited but space-constrained, this chemistry is usually a strong candidate.

Part 8. Is This Battery Safe for Mass Production?

Yes—when paired with the correct protection and charging design.

PCM design matching your charging voltage
UN38.3, IEC-related testing support
Sample validation before mass production
Engineering support during integration

High voltage does not mean unsafe—it means design discipline matters more.

Part 9. Final Takeaway

The 3.87V 1300mAh High Voltage Li-ion Battery 703440 is not for every product—but it is ideal when:

You need more energy without increasing size
Your system supports or can adopt 4.45V charging
Customization and long-term supply stability matter

Ufine Battery doesn’t just sell cells—we help tailor high-voltage batteries to real products.

FAQs

Can multiple cells be safely connected in series or parallel?

Yes, but it requires proper balancing and protection circuits to ensure consistent voltage and prevent overcharge or over-discharge in multi-cell configurations.
Is this battery RoHS and REACH compliant?

Yes. Ufine Battery ensures all cells meet major environmental compliance standards including RoHS and REACH, making them safe for global markets.
How long does it take to fully charge the battery?

Charging time depends on the charger current, but with a recommended high-voltage 4.45V charger, full charge typically takes 2–3 hours at 0.5C rate.
Can this battery support high-current discharge for short bursts?

Yes. The 703440 cell is designed to handle moderate peak currents, making it suitable for devices that occasionally demand high power, such as sensors or portable electronics.
Does this battery require a specific charging profile?

Yes. To ensure safety and longevity, it should be charged using a high-voltage compatible charger with proper constant-current/constant-voltage (CC/CV) profile for 4.45V cells.
Can this battery be used in custom-shaped enclosures or unusual form factors?

Yes. Ufine Battery offers customization of cell size, thickness, and connectors, allowing the battery to fit non-standard layouts without compromising performance.

Ready to Power Your Project?

We’ll help you design the perfect power source — tailored to your voltage, capacity, size, C-rate, and performance needs.

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