21700 DIY Power Bank Case | PD 20W Fast Charge USB-C Kit

Build Your Own Portable Charger — No Soldering Required!

Take control of your charging setup with this 21700 DIY Power Bank Case. Designed for electronics enthusiasts and everyday users alike, this solder-free kit lets you assemble a compact, fast-charging power bank in minutes. Just drop in a single 21700 flat-head battery and you're ready to go — no wiring, no mess, no expertise needed.

Made in Mainland China.

Why You'll Love It

• Zero Soldering Needed: Welding-free design makes assembly quick, safe, and beginner-friendly — perfect for DIY electronics hobbyists.
• PD 20W Fast Charging: Supports Power Delivery up to 20W output, compatible with all mainstream USB-C devices for speedy, efficient charging.
• Built-In USB-C Cable: Comes with a detachable Type-C dual-line cable (C-to-C) stored right inside — no more scrambling for a cable when you're on the go.
• Easy Disassembly: The snap-open shell makes it simple to swap batteries or repair the circuit board, extending the lifespan of your power bank.
• Ultra-Compact & Portable: Designed specifically for a single 21700 cell, this slim case slides into any pocket, bag, or commuter kit with ease.
• Smart Battery Indicator: Four LED indicator lights show real-time battery level — all four light up solid when fully charged, and a green light indicates active fast charging.
• Multi-Protection Safety Circuit: Built-in overcharge, over-discharge, overvoltage, and overcurrent protection keeps your devices and battery safe at all times.

Technical Specifications

What's in the Box

• 1× Power Bank Case (battery not included)

Installation Tips

Insert your 21700 flat-head battery, paying close attention to polarity — the spring contact is the negative (–) pole. Secure the shell, and your DIY power bank is ready to charge!

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For guidance on safe battery handling and lithium-ion cell standards, visit the U.S. Consumer Product Safety Commission – Lithium-Ion Battery Safety.

Frequently Asked Questions

Q: Does this 21700 power bank case come with a battery included?

A: No, the 21700 battery is not included. You will need to purchase a single flat-head 21700 lithium-ion cell separately. Make sure to use a flat-top (unprotected or protected flat-head) 21700 battery for proper fit and performance.

Q: Does this DIY power bank case support fast charging for iPhones and Android devices?

A: Yes! The case supports PD 20W fast charging via its USB-C bidirectional port, making it compatible with most modern iPhones (iPhone 12 and later) and Android devices that support USB Power Delivery. The USB-A port provides standard fast charging output as well.

Q: Do I need any tools or soldering skills to assemble this power bank case?

A: Absolutely not! This DIY power bank case features a solder-free (welding-free) design. Simply insert your 21700 battery, observe the correct polarity (spring = negative), and close the shell. No tools, no soldering iron, and no technical expertise required.

Q: How do I know when the power bank is fully charged or fast charging?

A: The case has four LED indicator lights that display the current battery level. When all four LEDs are solid, the battery is fully charged. A green indicator light activates specifically when fast charging is in progress, so you always know the charging status at a glance.