RTC seems to not work

[dkadish]

Not sure what the problem is, but needs to be fixed.

[dkadish]

The problem, identified by testing the differences between my board and the data logging carrier board with a multimeter, is that the positive battery terminal on the BAIT is shorted to ground. This is not true in the unpopulated boards and the connection seems to be slightly weaker on the resistor and diode terminals, so I suspect there is an accidental solder joint between the + and - terminals on the battery itself. Perhaps resoldering would fix it? I can pull off components one-at-a-time to check.

This should be added to the test regime.

[dkadish]

Can't seem to fix it with a reflow (heat and re-set) of the solder. Don't know if the issue is the battery or the soldering job. Either way, use a different battery. Possibly a proper coin cell? Or find another RTC battery

[dkadish]

Check the diodes as well

[dkadish]

Suggestion: Replace the Teensy RTC entirely with a RC-3028-C7 ultra-low power RTC.

Datasheet: RV-3028-C7_App-Manual.pdf

p 105 describes how to wire in a supercap for long term power.

[dkadish]

Sparkfun has it on a board (https://www.sparkfun.com/products/retired/15486) The guide (https://learn.sparkfun.com/tutorials/sparkfun-gatorrtc-hookup-guide/resources-and-going-further) The schematic (https://cdn.sparkfun.com/assets/7/1/6/d/8/gator_rtc_schematic.pdf?_gl=1*slh892*_ga*MTYxNTg2ODU1My4xNjk4ODI2MDcz*_ga_T369JS7J9N*MTcwNjU3MDA5Ny4zNy4xLjE3MDY1NzAxNDYuMTEuMC4w)

[dkadish]

This is a good basis with a supercap: https://core-electronics.com.au/makerverse-real-time-clock-rtc-with-supercapacitor-backup.html

Used a slightly bigger cap: https://www.digikey.se/en/products/detail/kemet/FC0H224ZFTBR24/4291007

[dkadish]

Done and added a 3v coin cell as well for double backup. Coin cell may be needed for Teensy powerup.