Overview
The LiitoKala Lii-40A 21700 4000 mAh is a high-drain rechargeable Li-ion cell designed for devices that demand both power and runtime. Featuring low ≤20 mΩ internal resistance and consistent 3.7 V output, it provides stable performance across multiple applications — from flashlights and e-bikes to DIY battery packs and energy storage modules.
Main Features
- 4000 mAh nominal capacity for balanced runtime and power
- 3.7 V nominal voltage, 4.2 V charge limit
- ≤20 mΩ internal resistance for efficient discharge and low heat
- Up to 1000 recharge cycles for long-term use
- 21700 format (21.5 mm × 70.5 mm) — higher energy density than 18650
- Supports custom versions (Nickel, Pointed, PCB Protected)
- Genuine LiitoKala cell tested for safety and stability
Technical Specifications
| Parameter | Specification |
|---|---|
| Brand Name | LiitoKala |
| Model | Lii-40A |
| Type | Li-ion 21700 Rechargeable Battery |
| Nominal Capacity | 4000 mAh |
| Nominal Voltage | 3.7 V |
| Limited Charge Voltage | 4.2 V |
| Working Voltage Range | 2.75 – 4.2 V |
| Internal Resistance | ≤ 20 mΩ |
| Recharge Cycles | Up to 1000 |
| Weight | 65 g ± 1 g |
| Size | Ø 21.5 mm × 70.5 mm |
| Customization Options | Nickel / Pointed / PCB |
| Package Details | 256 pcs / box (22 × 22 × 18 cm) |
Applications
The Lii-40A 21700 cell is ideal for flashlights, power tools, and e-bikes, providing consistent high-drain output and long runtime.
It is also used in RC projects, energy storage systems, and DIY battery packs that require efficient current delivery and stable performance.
Thanks to its optimized energy density and low internal resistance, it offers both power and efficiency for industrial and consumer applications.
Product FAQ
Is the Lii-40A protected or unprotected?
The standard cell is unprotected; PCB-protected versions are available on request.
How does it compare to 18650 batteries?
The 21700 format offers ~30% more capacity and higher current output in a similar form factor.
What devices is it best for?
High-drain equipment such as flashlights, e-bikes, and power tools.
What charger should I use?
Use a LiitoKala smart charger like the Lii-C6 Smart Charger.
Can it be used in battery packs?
Yes — ideal for multi-cell configurations when matched and BMS-balanced.
Does it work in cold environments?
Yes, but performance may decrease below 0 °C and recover when warmed.
Do you offer bulk purchase options?
Yes — visit our Bulk Batteries page for retail and OEM orders.
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