Realtime Clock in Arduino: Difference between revisions

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Power draw for Arduino on standby on 3.7V is about 20ma. So uses about 1.5Whr every 24 hours.
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.
See more about [[Relay#Power Draw]]
 
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 07:13, 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.

See more about Relay#Power Draw

External

Module is cheap - [1]