Are the 21700 batteries included in this DIY case kit?

No, this product is the power bank enclosure only and does not include batteries. You will need to purchase two 21700 lithium batteries separately to make the case functional. You can buy compatible 5000mAh batteries directly from our online store or physical shop.

Is this DIY case better than buying a pre-made power bank?

Yes, building your own power bank allows you to ensure the quality and true capacity of the internal battery cells. Pre-made power banks often degrade quickly, but with this DIY case, you can easily swap out old 21700 batteries for new ones, saving money and reducing electronic waste.

What happens if I insert the 21700 batteries upside down?

Inserting the batteries with reversed polarity will instantly short-circuit and permanently destroy the power bank's motherboard. You must carefully align the positive (+) and negative (-) terminals of the batteries with the markings inside the case before snapping it shut.

Can I buy the required 21700 batteries at your Sham Shui Po store?

Absolutely! Sun Cheong Computer Co. Ltd. stocks a wide variety of high-quality lithium batteries, including the required 21700 cells. You can order the case and batteries online and pick them up instantly at our Sham Shui Po physical store.

How do I turn the power bank on and off?

Operation of the DIY power bank is very straightforward. Simply press the power button once to turn the power bank on and activate the digital display. To turn the power bank off manually, press the power button twice in quick succession.

22.5W PD Power Bank Enclosure

Name: 22.5W PD Power Bank Enclosure | 21700 DIY Kit
Brand: Sun Cheong Computer Company Limited
SKU: 21BY000328
Price: 188.0 TWD
Availability: InStock

Short Product Description

Take control of your mobile power with the DIY 2x 21700 Battery Power Bank Case. Delivering PD 22.5W fast charging in a pocket-sized 9cm x 7.6cm shell, this enclosure features a built-in Type-C lanyard cable, a smart digital display, and dual ports (USB-A and Type-C). It is perfect for tech enthusiasts wanting to build a true 10000mAh portable charger without relying on fake, low-quality factory cells.(Note: Batteries are NOT included). Need reliable lithium cells for your build? Sun Cheong Computer Co. Ltd. (新昌電腦有限公司) has 20 years of electronic component expertise. Visit our Sham Shui Po physical store for instant pickup and expert DIY technical advice!

Key Features

Customizable Capacity: Fits two 21700 lithium batteries (not included), allowing you to build a true, high-capacity power bank.
PD 22.5W Fast Charge: Advanced circuitry supports high-speed charging for modern smartphones, including the iPhone 15 series.
Built-in Type-C Lanyard Cable: Features an integrated orange Type-C cable that acts as a convenient, durable carrying loop.
Dual Port Design: Equipped with 1x USB-A output port and 1x Type-C input/output port for versatile connectivity.
LED Digital Display: Shows precise battery percentage so you never have to guess how much power is left.
Compact & Portable: Measuring just 9cm x 7.6cm x 2.7cm, it easily fits into any pocket or small everyday carry (EDC) bag.

Full Product Description

Build Your Own High-Speed Portable Charger

Take control of your mobile power quality with this customizable DIY 21700 battery case. Pre-made power banks often use cheap, degraded internal cells that lose capacity quickly. By building your own power bank using this premium enclosure, you can select high-quality 21700 lithium-ion batteries to ensure maximum lifespan and true capacity. It is the ultimate, cost-effective solution for DIY makers, frequent travelers, and tech repair technicians who demand reliable power.

PD 22.5W Fast Charging & Built-in Cable

Charge your devices rapidly without carrying a tangled mess of extra wires. This smart enclosure is equipped with an advanced motherboard supporting PD 22.5W two-way fast charging. It features a standard USB-A output port, a Type-C input/output port, and a highly convenient built-in orange Type-C cable that doubles as a carrying lanyard. Whether you are charging an Android smartphone, an iPhone 15, or a tablet, this DIY case delivers optimal power efficiently.

Smart Digital Display & Easy Operation

Monitor your exact battery percentage and fast-charge status at a glance. The sleek black casing features a hidden digital LED display that shows your remaining power from 1% to 100%. Operation is incredibly simple: press the power button once to turn the device on, and press it twice to turn it off.

💡 Pro Tip from Our Technicians

"When assembling your DIY power bank, NEVER reverse the battery polarity! Always double-check that the positive (+) and negative (-) ends of your 21700 batteries match the markings inside the battery slots. Inserting them upside down will instantly short-circuit and permanently burn the internal motherboard. Please note that this case does not include batteries. If you need reliable, high-capacity cells, you can purchase our 2pcs 21700 5000mAh Lithium Batteries here. Drop by our Sham Shui Po store, and our team at Sun Cheong Computer Co. Ltd. will gladly help you assemble it safely!"

Technical Specifications

Product Type: DIY Power Bank Enclosure (Batteries NOT Included)
Supported Batteries: 2x 21700 Lithium-ion Batteries
Maximum Output Power: 22.5W (PD Fast Charging)
Input Ports: 1x Type-C
Output Ports: 1x USB-A, 1x Type-C, 1x Built-in Type-C Cable
Operation: Single click to turn ON, Double click to turn OFF
Dimensions: 9cm x 7.6cm x 2.7cm
Safety Warning: Reverse polarity will destroy the motherboard. Ensure correct +/- alignment.

Delivery Options

Local delivery within Hong Kong and in-store pickup.
Free shipping for orders of HK$400 or above; HK$35 shipping fee for orders below HK$400.
Shipped by SF Express, usually dispatched the same day for orders confirmed before 6:00 PM (Mon–Sat).
Estimated delivery time: 1–3 business days after dispatch (Hong Kong).
In-store pickup details (location and time) will be confirmed by email or phone message.
Delivery times are estimates and may be affected by weather or unforeseen circumstances.

FAQ Section

Are the 21700 batteries included in this DIY case kit?No, this product is the power bank enclosure only and does not include batteries. You will need to purchase two 21700 lithium batteries separately to make the case functional. You can buy compatible 5000mAh batteries directly from our online store or physical shop.
Is this DIY case better than buying a pre-made power bank?Yes, building your own power bank allows you to ensure the quality and true capacity of the internal battery cells. Pre-made power banks often degrade quickly, but with this DIY case, you can easily swap out old 21700 batteries for new ones, saving money and reducing electronic waste.
What happens if I insert the 21700 batteries upside down?Inserting the batteries with reversed polarity will instantly short-circuit and permanently destroy the power bank's motherboard. You must carefully align the positive (+) and negative (-) terminals of the batteries with the markings inside the case before snapping it shut.
Can I buy the required 21700 batteries at your Sham Shui Po store?Absolutely! Sun Cheong Computer Co. Ltd. stocks a wide variety of high-quality lithium batteries, including the required 21700 cells. You can order the case and batteries online and pick them up instantly at our Sham Shui Po physical store.
How do I turn the power bank on and off?Operation of the DIY power bank is very straightforward. Simply press the power button once to turn the power bank on and activate the digital display. To turn the power bank off manually, press the power button twice in quick succession.

Target Users / Applications

DIY Electronics Hobbyists: Repurposing salvaged 21700 lithium cells from old electric vehicle battery packs or power tools into a functional, high-speed power bank.
Frequent Travelers & Commuters: Utilizing the built-in Type-C lanyard cable to charge devices on the go without carrying a tangled mess of extra wires.
Tech Repair Technicians: Creating a reliable, verifiable portable charger for testing USB-C devices and smartphones in the workshop.