C9 DIY 18650 Power Bank Case: Build a Custom Six-Cell Charging Kit

This C9 model DIY external battery kit provides the housing and circuitry to construct your own portable power bank using standard 18650 lithium-ion cells. Designed for hobbyists and users seeking a tailored power solution, it accommodates six individual cells to determine total capacity based on the batteries you select. The unit features dual input charging through both Type-C and Micro USB ports, offering compatibility with common cables, and delivers a regulated 5V 2A output suitable for charging smartphones, tablets, and other USB-powered devices. Its compact form factor, measuring 22mm by 76mm by 150mm, maintains portability for travel, work, or outdoor use.

Features and Construction

The C9 kit is centred around its modular design, allowing you to source and install your preferred 18650 cells. This section details its physical build and core electrical specifications.

Material and Build

The case is constructed from a durable plastic housing that securely holds the internal battery cells and printed circuit board. The electronics are designed to manage the input and output power flows, supporting the dual charging inputs and providing a stable 5V 2A output. The build focuses on functionality for the DIY assembly process, with clear battery compartment layout and accessible ports.

Size and Practical Fit

With external dimensions of 22mm in thickness, 76mm in width, and 150mm in length, the case is designed to be slender and hand-held. This size efficiently packs six 18650 cells in a rectangular layout, resulting in a power bank that can easily fit into a backpack, briefcase, or larger pocket. The measured dimensions are based on manual methods, so a tolerance of 1–3cm should be anticipated.

Uses and Placement

This DIY kit suits users who need a reliable, customisable power source away from mains electricity. Its applications range from casual daily use to more prepared scenarios.

Event or Professional Use

For events, tradeshows, or fieldwork where access to charging points is limited, this power bank can be assembled with high-capacity 18650 cells to provide extended backup power. The 5V 2A output is compatible with most consumer electronics, allowing you to keep cameras, communication devices, or presentation tools operational. The dual input charging means you can recharge the bank using whichever cable is available at a power source.

Everyday Home Use

Around the home or office, the kit serves as a centralised charging bank for multiple devices. You can cycle through charging phones, wireless headphones, or smartwatches without needing individual adapters. Choosing between the black or white colour option lets the unit blend with your décor or tech accessories. Its DIY nature means you can replace individual cells over time if performance diminishes.

Benefits and Buying Value

The primary advantages of this product stem from its customisability, straightforward design, and practical output specification.

Reuse and Low Maintenance

Because you supply the 18650 cells, you can utilise new or recycled cells from other projects, potentially reducing waste. The kit itself has no consumable parts beyond the user-provided batteries; the case and board are designed for repeated use. Maintenance involves simply ensuring clean contacts and occasionally checking cell performance.

Why Choose This Product

This DIY kit is selected for its clear specification—supporting six 18650 cells, dual input charging, and a 5V 2A output—all in a defined size. It avoids proprietary battery packs, giving you control over capacity and cell quality. The included components are ready for assembly, requiring no additional electronics work. For those comfortable handling lithium cells, it presents a cost-effective and adaptable alternative to pre-assembled power banks.