Hello!
After some days of operation my CR2032 battery (which was included) explodes. It was not dangerous, because battery case designed to this, but it makes loud click.
After this, I made some investigations:
- module is designed to work only with LIR2032 (rechargeable battery)
- LIR2032 nominal voltage is 3,6V, minimum safe voltage 3V, charging current is 20mA, maximum charging voltage is 4,2V 10mA
- voltage divider is to protect DS1307 Vbatt input from over-voltage. In my version R6/R4 = 510k / 1.5M. Which gives you 2,3V from 3V and 3,15 from 4,2 V.
- fast fix to use CR2032 (not rechargeable) is to cut track in charging circuit (between D1 and R6). But voltage divider will be sucking 1,5 uA current from battery, so divider should be also removed (remove R4 and short R6).
Tiny RTC.pdf (53.4 KB)
