Skira's Open UpCell Is an Open-Hardware Single-Cell Battery Management System with Flexibility

Pune-based Sikra, a self-described "open source consumer devices company," is preparing to launch an open-hardware battery management board for USB Power Delivery (USB-PD) for single-cell lithium ion batteries: the Open UpCell.

"Open UpCell is a USB Type-C PD single cell lithium-ion battery management system with either 5V or 3.3V outputs, up to 14V input, and an I2C interface for battery and charge status monitoring," company founders Ishan Daga and Padmalaya Rawal explain. "You can check battery fuel gauge, charge status, charge voltage selection, charge current selection, and more via the provided Arduino IDE and PlatformIO SDKs."

The board is designed, primarily, for broad compatibility. There are Grove-style JST-PH and STEMMA QT-style JST-XH four-pin connectors for power output as well as a 2.54mm (0.1") pin header for access to the I2C bus and both 5V and 3.3V outputs. There's short-circuit, over-voltage, over-current, and over-charge protection, a fused input, and a temperature-monitoring system, and the company boasts compatibility with "any capacity of lithium-polymer or 18650 cell, 21600 cell, or equivalent lithium chemistry cell" — though only a single cell per board.

"Open UpCell enables rapid prototyping of battery dependent projects while keeping things simple from setup to charging," the company claims. "It can be used to power existing Seeed Grove module chains and Adafruit STEMMA QT module chains. It can also keep your projects powered and usable off grid, perfect for some IoT [Internet of Things] and edge projects, like an IoT soil sensor cluster or a simple PIR motion detector. Open UpCell is also capable of being a simple, rudimentary inverter for a project, with an up to 15W output (5V, 3A) — enough to power a Raspberry Pi Board or small router."

Despite its impressive feature list, the Open UpCell is also compact — measuring only marginally more than the footprint of an 18650 cell. This, Sikra claims, makes it suited for wearable and embedded projects — though those needing uninterruptible power supply (UPS) functionality, where the battery kicks in automatically on loss of power, will need to implement it themselves in software, the company admits.

Sikra is currently preparing a crowdfunding campaign, with interested parties able to sign up to be notified when it goes live on Crowd Supply. Meanwhile, the schematics, Gerbers, and bills of materials (BOMs) for the Open UpCell 1.3 and 1.4 are available on the Sikra GitHub repository under the permissive MIT license.