Home - Products - INR21700 - 3C digital battery - INR21700-40C Small storage battery

INR21700-40C Small storage battery

Product Features:

High Energy Density

Stability

Lightweight

Lower Discharge Rate

Application Areas:

Power Bank
Small-Scale Energy Storage
3C Digital
Small Home Appliances
Security
Lighting

Parameter：

Cell's Materials	Ternary with manganese doping (4.5%)
Dimension (mm)	Height: 70.8±0.2mm
Dimension (mm)	Diameter: 21.7±0.15mm
Nominal Voltage (V)	3.6V
Nominal Capacity (Ah) (0.2c)	4000mAh
Internal Resistance (mΩ)	≤22mΩ
Weight	67.2±1g
Max Discharge Rate	4C
Max Charge Rate	1C
Cycle life (DOD 80% 25℃)	Charge:0.5C, Discharge:2C≥400 cycles Charge:0.5C, Discharge:1C≥500 cycles
Operating Temperature(Cell Surface)	Charge: 0~45℃ Discharge: -10~60℃

Next Product Inquire Now

The INR21700-40C lithium-ion battery is a high-performance lithium-ion battery designed for efficiency, reliability, and safety. With a 4000mAh capacity, low internal resistance, and stable energy output, it’s ideal for power banks, small-scale energy storage, 3C digital devices, home appliances, lighting, and security systems. Lightweight yet durable, this battery offers long cycle life and safe operation under various conditions.

Safety and Quality Highlights of INR21700-40C lithium-ion battery

Built-in protections against overcharge, over-discharge, and short-circuit.
Manufactured using high-quality ternary lithium-ion materials.
Tested for long-term stability, safety, and reliability.

Storage & Usage Tips

Store in a cool, dry place at around 40–60% charge for long-term storage.
Avoid exposure to direct sunlight or high temperatures.
Use compatible chargers to maximize cycle life.

Get reliable, high-capacity power with INR21700-40C – Order now!

Product Differentiation/Why Choose Joinsun:

01

Source Factory

With comprehensive services and quality assurance, employing cutting-edge technology and high-end materials to provide a longer average lifespan.
02

Professional Team and Advanced Production Equipment

A research and development team of over 30 people with 24 related patents. The company covers an area of 100 acres, equipped with 8 advanced coating production lines, 3 fully automated injection lines, 10 sets of fully automatic sheet winding machines, 6 fully automatic integrated welding production lines, etc., meeting the production capacity demand of 20GWh per day, ensuring product efficiency and quality.
03

Sales Network and Services

Jixin Technology has established offices in East China, South China, and an overseas affairs department, with sales networks gradually expanding to cover the Middle East and Southeast Asia regions. Striving to become a leading supplier in the power battery and energy storage lithium battery markets, providing comprehensive service and support.
04

High Cost-Effectiveness

Joinsun products provide high value for their cost.

Industrial Packaging That Can Be Customized According to Requirements.

* Warranty Policy: Provide warranty and replacement service within a certain period of time to ensure the interests of customers.

* Important Notes: Please strictly follow the instructions provided in the product manual.

Customer Feedbacks

JOINSUN battery packs a powerful punch. lt has never failed to provide enough energy to keep our devices running smoothly. From our smartphone to my portable speakers, this battery has got it covered.

Jacob

JOINSUN has provided us with customized lithium battery solutions for our energy storage systems. Their batteries are UL and CE certified, ensuring safety and reliability. Fast shipping and great customer support!

John

We needed custom lithium battery packs for our electric bikes, and JOINSUN delivered exactly what we wanted. Their R&D team helped optimize the design, and the production was quick. Definitely our go-to supplier for long-term cooperation!

Sarah

We've been sourcing 18650 and 21700 battery packs from JOINSUN for over a year. The battery quality is excellent, with stable performance, high capacity, and long cycle life. Their team is very professional and responsive. Highly recommended!