Increased energy density
The energy density of 21700 batteries reaches 300Wh/kg, 20% higher than that of 18650 batteries.
Increased Single Cell Capacity
The main capacity range is between 3000mAh and 4800mAh, a 35% increase compared to 18650 batteries.
Reduced Battery Pack Cost
With the same capacity as 18650 battery packs, fewer 21700 cells are needed.
Weight Reduction
Due to the reduced number of 21700 cells, the overall weight of the battery pack is reduced.
21700 Battery ion Pack Product
Below are some of the 21700 battery packs we produce: 1S1P 3.7V 5Ah battery pack and 2S1P 7.4V 5Ah battery pack. Of course, we can also produce different battery packs like 21700 12S2P 10Ah.
Based on your needs, we can customize 21700 battery packs.
21700 1S1P 3.7V 5Ah Battery
Nominal voltage: 3.7V
Nominal capacity: 5000mAh
Rated energy: 18.5Wh
Charge current: 1.0C rate
Discharge current: 3.0C rate
Diameter: ≤21mm
Length: ≤72.0mm
21700 2S1P 7.4V 5Ah Battery
Nominal voltage: 7.4V
Nominal capacity: 5000mAh
Rated energy: 37Wh
Charge current: 1.0C rate
Discharge current: 3.0C rate
Thickness: ≤22.0mm
Width: ≤44mm
Length: ≤72.0mm
21700 Battery Pack Applications
Due to its high energy density and long cycle life, the 21700 battery pack is gradually replacing nickel-metal hydride and nickel-cadmium batteries. It can provide more powerful power and longer runtime for power tools such as drills, electric hammers, and lawn mowers.
21700 batteries are also widely used in home and industrial energy storage, capable of storing solar and wind energy for long periods, providing stable power supply for homes and industries.
21700 battery packs are also suitable for products like flashlights and robots.
Additionally, 21700 battery packs can be used in ebike, medical equipment, aerospace, military equipment, and other fields.
Lithium Battery Factory-direct Pricing
- Minimum Order Quantity: 500 pieces per model.
- All orders come with the necessary certificates.
- Any model can be customized in terms of voltage, capacity, size, and charge/discharge rate.
How calculate 21700 battery pack
Everyone hopes for a quick calculator to help them DIY 21700 battery packs, but due to the varying voltage and capacity of each cell, the situation is complex. We can assist in designing 21700 battery packs for free.
Before calculating lithium battery packs, please understand the basic knowledge of 21700 battery design. Determine the following requirements for your battery application:
- Nominal Voltage: Single cell voltage is 3.7V, 2S voltage is 7.4V, 3S voltage is 11.1V, and so on.
- Standard Charging Current: Generally recommended current is 0.2C or 0.5C rate.
- Maximum Charging Current: Generally recommended current is 1C or 3C rate.
- Standard Discharge Current: Generally recommended current is 0.2C or 0.5C rate.
- Maximum Discharge Current: Generally recommended current is 1C or 3C rate. Some cells support 5C, 10C, or even higher rates.
- Starting Current and Time: Each customer’s requirement varies. Typically, it is 3C or 5C rate starting current, with 5 milliseconds or 10 milliseconds starting time.
- Minimum Capacity: Capacity can be increased by parallel connection to meet long working hours requirements.
- Run Time: Theoretically, 1C discharge rate gives approximately 55 minutes of run time. Some dynamic rates require reevaluation.
- Battery Pack Dimensions (Length, Width, Height): Provide the dimensions of the reserved battery compartment in the device.
- Determine Same-Port or Different-Port Output: Some battery packs have the same port for charging and discharging, while others have different ports.
- Charging Terminal or Connector Model: Molex, JST, XT30, XT60, EC3, EC5, etc. Consider the pin pitch as well, commonly 1.25mm, 1.5mm, 2.0mm, 2.54mm.
- Wire Length: The length from the external battery pack to the device’s mainboard.
21700 Battery Pack Combination
21700 battery packs are formed by connecting multiple 21700 cells in series (S), with each cell increasing the voltage to reach the required total nominal voltage. Parallel (P) connections add the battery diagram capacities in Ah to achieve the needed capacity.
Below is a simple diagram of our 21700 battery packs in series and parallel configurations. Series connection means connecting the positive and negative terminals of each cell, while parallel connection means connecting the positive terminals together and the negative terminals together.
Besides these basic 21700 battery details, we also need to consider protection board design and placement, whether a casing is needed, or if simple PVC wrapping will suffice. Since lithium batteries are the main power source for the entire device, we must ensure their safety and reliability. We are a professional lithium battery factory in China, welcome to consult with us to solve your problems.
How to DIY 21700 Battery Pack
To DIY a 21700 battery pack, follow these steps:
- 21700 Cells: Choose the appropriate battery model for your needs, such as Molicel P42A or Samsung 40T.
- Nickel Strips: Used for connecting battery cells, preferably 2.0mm thick.
- Battery Management System (BMS): For monitoring cell voltage, internal resistance, capacity, and temperature.
- Insulation Materials: Fish paper, high-temperature tape, heat shrink tubing.
- Welding Equipment: Such as a spot welder (Kweld) or a soldering iron.
- Wires: Select the appropriate gauge wire (e.g., AWG 10).
- Connectors: Such as XT90 connectors, for connecting the battery pack to the device.
21700 Battery Pack DIY Steps
Test the Cells: Before assembly, match the cells to ensure all battery units are in good condition with consistent voltage, internal resistance, and capacity.
Assemble Battery Modules: Group the battery cells according to your design (e.g., 12S4P). This means each group has 4 parallel cells, and there are 12 such groups in series.
Weld Nickel Strips: Use the spot welder to weld the nickel strips to the positive and negative terminals of the battery cells, ensuring solid connections.
Insulation Treatment: Use insulating tape and fish paper to insulate the battery pack, preventing internal short circuits.
Connect BMS: Follow the BMS manual to connect it to the appropriate positions on the battery pack. Ensure correct connections and pay attention to the order and position of the signal wires.
Test the Battery Pack: Before connecting to the device, test the voltage and current of the battery pack to ensure normal output.
Packaging: Place the battery pack into a suitable casing.
Whole Machine Testing: Once the battery is integrated into the final device, test the overall operation of the device.
Following these steps will help you successfully DIY a 21700 battery pack.
Lithium-ion battery production process
#1 Cell Selection
Select the quanitities of 21700 battery cells you need. Ensure they works fine.
#2 Battery Sorting
Make sure that the capacity, voltage, and internal resistance of the selected cells are consistent.
#3 Arrangement & Assembly
Combine the required battery modules in a series-parallel manner.
#4 Spot Welding
The positive and negative terminals of the battery are connected via nickel tabs to form the desired capacity or voltage.
#5 Mounting Protection Board
Connect the protection board on the battery pack to ensure that its overcharge, overdischarge and short circuit protection functions properly.
#6 Packaging & Aging
Wrap the battery pack in a PVC or metal casing while charging and discharging to activate the battery pack performance.
