This "Cybertablet" Aims to Power a Raspberry Pi Touchscreen Tablet with a Stack of AA Batteries
10 AA batteries in a cartridge which doubles as a grip — but how long they'll last isn't yet known.
Pseudonymous maker "Personalitysphere," hereafter simply "Sphere," is working on a Raspberry Pi-based tablet called the "Cybertablet," which is powered by a stack of standard AA batteries, housed in a cartridge that doubles as a grip.
"On this prototype I’m experimenting with different grip styles on the handle: one webbed/recessed design and one ribbed version to see which feels better in hand," Sphere explains of the project's second prototype. "I also assembled a battery cartridge. It’s not soldered up yet, I just put together for fitment testing at this stage. The idea is to transfer power directly from the batteries through a magnetic pogo-pin connector into the tablet via a matching connector. Inside the tablet, a buck converter steps the voltage down to a stable 5.1V for the Raspberry Pi."
Using a Raspberry Pi single-board computer to power portable cyberdeck builds is nothing new, and even opting for a tablet form-factor isn't unusual — but what makes the Cybertablet stand out is its choice of power source. Rather than a lithium-ion or lithium-polymer battery and charging system, or even the easy option of an off-the-shelf USB battery bank, Sphere's design uses either standard alkaline or rechargeable AA batteries.
Powering portable electronics with AA batteries was par for the course in the 1980s and 1990s — the Cambridge Computers Z88 slab-like ultra-portable laptop takes four AA cells in the back, while Hewlett-Packard's later MS-DOS-powered "Project Felix" 200LX and associated palmtops managed with just two plus a button-cell battery for the real-time clock. A Raspberry Pi, though, is somewhat more power-hungry, as is a full-color touchscreen display — so the Cybertablet takes a whopping 10 AA batteries, housed in a quick-connect cartridge that doubles as a grip.
"I honestly have no idea how much battery life I'll get out of 10 AA cells with the screen and all," Sphere admits, "but I will find out I guess. [Currently] two banks of five [batteries] in series are connected in parallel. If I increase the chassis length 10mm, I could fit 15 batteries, but then the weight would be too much. For daily use I intend to build a rechargeable pack."
More information is available in Sphere's Reddit post.