For power users loaded with a laptop, tablet, drone, a robot, and, of course, a smartphone, the ordinary power bank options do not make the cut. The amount of power required to keep these gadgets juiced up is considerable, especially when on the go. The only solution is a custom-made power bank that suffices all the needs of your power-hungry gadgets.
A custom-built portable power station offers a high-capacity solution for people who need to run multiple devices without reliable access to wall power. Standard consumer power banks are often too limited for users carrying a laptop, phone, tablet, router, and other gear at the same time, especially in remote or mobile situations. To solve this problem, creator Luq1308 developed the Omnibus 4×8, a DIY backpack-friendly power bank with enormous capacity and flexible output options.
Designer: Luq1308
The heart of this project is a dense battery pack made from 32 brand-new 18650 lithium-ion cells arranged in a 4S8P configuration. Each cell is rated at 3000 mAh, and when assembled into the pack and scaled for usable voltage, the complete system delivers roughly 96,000 mAh, equivalent to about 345 watt-hours (Wh) of stored energy. This substantial capacity makes it suitable for powering a range of electronics for prolonged periods without recharging. Critical to the build is a battery management system (BMS) rated for 4S and 30 amps. The BMS monitors and balances the individual cells, prevents overcharging and deep discharge, and includes multiple safety fuses. The system also draws very little power at rest, with a standby current of less than 400 microamps, helping to preserve stored energy when the unit is not in active use.
The Omnibus 4×8 offers a wide range of outputs to suit both everyday gadgets and more demanding equipment. There are four USB-C ports, each capable of delivering up to 36 watts, which is enough to charge phones and tablets simultaneously. A 100 W bidirectional USB-C port supports fast laptop charging and can also accept power input from compatible charging sources. For broader custom needs, a DC jack provides adjustable outputs between 2.7 V and 20 V, and a high-wattage XT60 connector can handle loads exceeding 400 W. A dedicated 150 W AC outlet enables the use of small appliances through an inverter, expanding the range of devices that can be supported.
Inside the power station, an ESP32-C3 microcontroller oversees system operations. It reads real-time data such as voltage, current, and temperature from sensors and displays this information on a 1.3-inch OLED screen with simple navigation buttons. Four temperature sensors monitor the battery pack, heatsinks, and inverter, and dual 40 mm cooling fans are triggered as needed to manage heat during high loads. Custom aluminum heatsinks with thermal pads are included to further reduce thermal stress.
The enclosure combines hand-cut G10 fiberglass plates for strength with 3D-printed ABS plastic sides in a subdued matte black finish. Brass spacers and mesh vents enhance airflow and protect internal components while maintaining a rugged aesthetic suitable for outdoor use. Internally, thick-gauge silicone wiring and a perfboard distribution bus with fuses connect the various modules safely and efficiently.
One notable feature of this DIY build is its adaptability. The inverter was modified to work across the full battery voltage range, and the system can accept solar input with maximum power point tracking (MPPT) for efficient off-grid recharging. All design files have been made open source on GitHub, allowing others to replicate or expand on the concept.
