After a few teasers, here’s the first fully functional version of my USB micro-ohmmeter.

Originally designed to test contact resistances in EV charging connectors, it’s now proving to be a precise and repeatable measurement tool for shunts, cables, and low-resistance connectors of all kinds.

Key Specs

• Measurement range: 0–100 mΩ (more to be tested)
• Resolution: < 2 µΩ
• Calibrated: Using precision resistors (100 µΩ, 1 mΩ, 10 mΩ)
• Interface: USB-C with SCPI command set

The first measurement results are even better than expected — especially in terms of stability and effective resolution.
For example, the ADC output shows about 88 counts when measuring a 100 µΩ shunt, which translates to an estimated resolution of ~1.14 µΩ.

Looking for Early Testers

I’m now looking for early testers interested in trying out this first version. If you work with low-resistance measurements and would like to give feedback on performance, usability, or possible improvements, please leave a comment or send me a message.

Your input will directly shape the next revision — which I plan to release later on Tindie.

What’s Next

In the next project log, I’ll run a stability analysis and share some thoughts on calibration methods for milliohm measurements.