Key Features
- 4000mAh Capacity: Provides long-lasting power between charges for high-demand devices.
- 30A High-Drain Output: Delivers strong, steady current for demanding applications.
- Flat-Top Lithium-Ion Cell: Designed for devices that require flat-top battery contacts.
- IMR Chemistry: Engineered for stable and consistent performance under load.
- Rechargeable & Compact: 21700 size offers a balance of capacity, power, and portability.
Overview
The Efest 21700 4000mAh rechargeable lithium-ion battery combines high capacity with strong discharge performance in a compact 21700 format. With a 30A maximum continuous discharge rating and flat-top, unprotected design, this cell is intended for devices engineered to handle high-drain lithium-ion power. It’s a reliable option for users who need sustained energy and dependable output.
Applications / Uses
- 21700-compatible flashlights
- Portable power tools and equipment
- DIY electronics and custom battery assemblies
- Bench testing and evaluation projects
- Replacement batteries for compatible lithium-ion devices
Specifications
| Manufacturer: | Efest |
| Size: | 21700 |
| Nominal Capacity: | 4000mAh |
| Nominal Voltage: | 3.7V |
| Maximum Voltage: | 4.2V |
| Discharge: | 30A Maximum Continuous |
| Positive: | Flat |
| Protected: | No |
| Rechargeable: | Yes |
| Dimensions: | 21.3mm x 70.2mm |
| Weight: | 66.37g |
⚠ Important Safety Warnings
Improper handling or misuse of this lithium-ion battery can result in FIRE, EXPLOSION, or THERMAL RUNAWAY, causing personal injury, property damage, or death. Users must read and follow all safety guidelines before purchase and use. Click here to review the full safety guidelines.
- Critical Warning: Never carry loose batteries in your pocket, purse, or bag. Loose batteries can come into contact with metal objects like keys or coins, causing a short circuit, which may result in severe burns, fire, or explosion. Always store or transport batteries in a protective case.
- Intended Use: This battery is designed for integration into protected battery packs with a Battery Management System (BMS) or Protection Circuit Board (PCB). It is not intended for standalone use or for e-cigarettes, vaporizers, or similar devices.
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Thermal Runaway: A chain reaction where heat from a failing battery
causes further overheating, potentially leading to fire or explosion.
- Causes: Overcharging, short circuits, physical damage, or exposure to high temperatures.
- Prevention: Use a smart charger, avoid damage, and store batteries in a cool, dry place.
- Storage & Transport: Always store batteries in protective cases to prevent accidental contact with metal objects. Never store loose batteries in pockets, purses, bags, or near conductive materials.
- Inspection: Do not use if the PVC wrapper, terminal insulator, or casing is damaged, dented, leaking, or bulging. Continued use could result in failure, fire, or explosion.
- Charging: Use a smart charger specifically designed for lithium-ion batteries and ensure the charger's voltage matches the battery's specifications. Never overcharge, over-discharge, or leave unattended while charging.
-
Prohibited Activities:
- Do not expose the battery to extreme heat, fire, or liquids.
- Do not short circuit, puncture, crush, or modify the battery.
- Do not charge or discharge beyond the manufacturer’s voltage range.
- Do not dispose of in regular trash—always recycle at approved facilities.
- Emergency Response: If the battery overheats, emits smoke, or swells, move it to a non-flammable surface (e.g., sand or concrete) and stop use immediately. In case of fire, use a Class D fire extinguisher or sand. Do not use water.
Disclaimer
18650Battery.com is not responsible for any damages, injuries, or claims arising from improper use, handling, or failure to follow these safety guidelines. Lithium-ion batteries require strict adherence to all safety protocols. It is the reseller's responsibility to ensure all safety warnings and product guidelines are effectively communicated to customers. Users and resellers assume full responsibility for the safe handling, usage, and distribution of this product.