Realtime Clock in Arduino: Difference between revisions
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A solid state relay will draw .1W on the driving side, but the load side loses significant power (1V drop). 20W loss when running a 20A load - significant through the day. | A solid state relay will draw .1W on the driving side, but the load side loses significant power (1V drop). 20W loss when running a 20A load - significant through the day. | ||
May want a mechanical relay. | May want a mechanical relay. Sainsmart relay is 15-20mA at 5v to energize. And no voltage drop on the power side, as it's not going through a transistor like in a solid state relay. | ||
=External= | =External= | ||
Revision as of 06:52, 19 March 2021
Internal
Arduino has an internal clock. Is shut down if Arduino loses power. Can use 3.7 battery for power. Library is RTC.h.
https://www.arduino.cc/en/Reference/RTC
Power draw for Arduino on standby on 3.7V is about 20ma. So uses about 1.5Whr every 24 hours.
A solid state relay will draw .1W on the driving side, but the load side loses significant power (1V drop). 20W loss when running a 20A load - significant through the day.
May want a mechanical relay. Sainsmart relay is 15-20mA at 5v to energize. And no voltage drop on the power side, as it's not going through a transistor like in a solid state relay.
External
Module is cheap - [1]