Overview
The 21700 3.7V 3500mAh rechargeable Li-ion battery is a single-cell lithium battery pack designed for DIY electronics, RC devices, toys, LED lighting, small robots, portable instruments, wireless modules, and other low-voltage equipment. It uses a 21700 lithium battery cell, with a 3.7V nominal voltage, 3.6–4.2V operating voltage range, and 3500mAh capacity for longer runtime and stable performance.
This product is available in two connection styles: XH2.54 red-black connector and red-black wire leads. The XH2.54 version is suitable for devices with a matching 2-pin battery plug, while the wire leads version is suitable for soldering, DIY wiring, or custom connector replacement.
Available Options
| Option | Connector Type | Description |
|---|---|---|
| 21700 3.7V 3500mAh Battery with XH2.54 Connector | XH2.54 red-black plug | Ready-to-use version for devices using a 2-pin XH2.54 battery connector |
| 21700 3.7V 3500mAh Battery with Wire Leads | Red-black wire leads | No plug included, suitable for soldering, custom wiring, or connector replacement |
Key Features
The 21700 3.7V 3500mAh battery offers a practical balance of compact size, rechargeable performance, and longer runtime. With a 3500mAh capacity, it is suitable for many small devices that require more battery life than lower-capacity lithium packs.
The battery includes an intelligent IC protection board, designed to help protect against overcharge, over-discharge, and abnormal use conditions during normal charging and discharging. This makes it more suitable for replacement battery applications and DIY projects compared with unprotected bare cells.
The XH2.54 connector version includes red and black wires with a 2-pin plug, while the wire leads version provides red and black output wires for flexible installation. The wire leads version shown in the image has approximately 15cm wire length, making it convenient for DIY connection or soldering.
Specifications
| Parameter | Details |
|---|---|
| Product Type | Rechargeable Li-ion Battery |
| Cell Type | 21700 Lithium Battery |
| Nominal Voltage | 3.7V |
| Operating Voltage Range | 3.6V–4.2V / 3.7V–4.2V |
| Full Charging Voltage | 4.2V |
| Capacity | 3500mAh |
| Battery Configuration | Single Cell / 1S |
| Diameter | Approx. 21mm |
| Length | Approx. 70mm |
| Connector Options | XH2.54 connector / wire leads |
| Wire Color | Red and black |
| Wire Length | Approx. 15cm for wire leads version |
| Protection Board | Built-in IC protection board |
| Rechargeable | Yes |
Connector Details
| Version | Output Type | Best For |
|---|---|---|
| XH2.54 Connector Version | 2-pin XH2.54 red-black plug | Direct replacement for devices using the same XH2.54 plug |
| Wire Leads Version | Red and black wires without plug | DIY electronics, soldering, custom connector installation, battery replacement projects |
The red wire is normally positive (+), and the black wire is normally negative (-). Before installation, please compare the polarity of your original battery connector. Some devices may use the same plug size but different positive and negative wire positions.
Applications
This 21700 3.7V 3500mAh rechargeable battery can be used for DIY electronics, RC models, educational kits, small robots, LED lights, wireless devices, toys, portable equipment, and other products requiring a 3.7V single-cell Li-ion battery pack.
Package Includes
| Selected Option | Package Content |
|---|---|
| XH2.54 Connector Version | 1 × 21700 3.7V 3500mAh battery with XH2.54 red-black connector |
| Wire Leads Version | 1 × 21700 3.7V 3500mAh battery with red-black wire leads |
Important Notes
Please confirm the battery voltage, capacity, connector type, plug size, and wire polarity before purchase. The XH2.54 connector must match your device socket. If your device uses a different connector or polarity, choose the wire leads version or replace the connector carefully. Do not reverse-connect, short-circuit, puncture, crush, overcharge, over-discharge, or expose the battery to high temperature.
