The goal for this test was to verify that the overvoltage and undervoltage protection limits for the energy harvesting subsystem are hitting their intended set points. 

Result: PASS

Procedure

To simplify this test I isolated the solar harvester from the system, and provided a relatively small capacitor instead of a LIPO or LIC.

• Isolate Boost Converter: Removed R28 to disconnect the downstream boost circuitry.
• Temporary Storage: Populated a 1000uF capacitor onto the battery pins (J9/J10).
• Power Source: Connected a solar cell to J1.

Overvoltage Limit & Hysteresis

For this capture, I probed Vsolar, Vbat, and the current into Vsolar. (Schematic above)

I was hoping to catch a glimpse of the MPPT (Maximum Power Point Tracking) at work here, but no dice. I suspect with a better light source I’d be able to witness the MPPT in action.

Undervoltage Limit

Using the same setup, I moved the VSOLAR probe to VSTOR to observe the disconnect behavior.

Next Steps

Now that the limits are verified, I can move back to full-system integration and see how these limits hold up under the varied load of the H-bridge pulses. For now I'll be testing with bulk caps in place of a LIPO. In the future these limits will likely be tightened further.