DIY Lithium Battery Upgrade for Uni-T UT33D Multimeter

If you're into DIY lithium battery projects, this article is worth a read. We've covered many lithium battery DIYs before, and this time, we're upgrading the Uni-T UT33D multimeter with a lithium battery.

This compact and budget-friendly multimeter has one major downside—it lacks an auto power-off function. Forget to turn it off, and by the next day, you'll need a new battery. Not exactly convenient. So, what’s the solution? Follow these steps to DIY a lithium battery upgrade.

You'll need a soldering iron, hot glue gun, double-sided adhesive, Teflon wires, a TP4056 charging module, a 9V boost module, and a lithium battery.

The lithium battery will be paired with a TP4056 charging module to ensure safe charging. 

You'll also need a small DC-DC boost module, which supports 5V/8V/9V/12V output and measures just 22×11×3.6mm—perfect for this project.

With some basic soldering, plus double-sided adhesive for securing the components, everything comes together. 

You can use a soldering iron to make two small holes for wiring. 

Then, fix the charging module in place with hot glue and cut a small opening in the battery compartment for the wires to pass through.

Once assembled, the boost module fits perfectly and even has a soft blue indicator light when in operation. 

Finally, reattach the back cover, tighten the screws, and you're all set.

Now, with the boost module's indicator showing available power, you won't have to keep replacing batteries. Job done!