Give Your Vintage TI Calculator a LiPo Upgrade

We’ve seen a massive shift over the past few decades from devices that take single-use batteries to devices with built-in rechargeable batteries. There are some environmental benefits, because fewer batteries end up in landfills. But the major driving factors are convenience and cost. Imagine if you had to swap out AAA batteries in your iPhone every morning — you’d have to buy those batteries by the pallet. Thanks to Nico Verduin, fans of vintage TI calculators can now experience that same convenience with a LiPo battery upgrade.

Verduin’s work is an extension of an earlier project completed by tomcircuit, which was a LiPo battery pack for TI-58 and TI-59 calculators. But while those two models are among the most popular in Texas Instruments’ history, there are many other models still in use by collectors, enthusiasts, and the kinds of people who like saying “they don’t make ‘em like they used to.” Verduin’s project brings lithium goodness to any Texas Instruments calculator that uses a BP-7, BP-8, or BP-9 battery pack—a large swath of vintage models.

This is a self-contained battery pack, with a 9V connector on one side and a USB port on the other side. The enclosure is 3D-printable and inside is a standard 3.7V lithium-polymer battery and a custom PCB. That PCB provides the connections and also a boost converter to bring the output voltage up to the 9V required by the calculator.

Once assembled, this should fit in the same place as the original battery pack. The only downside is that the USB port isn’t accessible from outside the calculator. That means that users will have to remove it to charge it back up. But that’s a lot better than buying boxes of batteries for people that use their old TI calculators on a regular basis.