Chat freely about anything...

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By liderbug
#71691 A project - rural mailbox - when the door is opened (mail's here) gpio pin X goes high, 8266 sends sms to phone.
A. How much solar panel is needed to keep ~3.3v battery (5v+3.3reg)? (I hate reinventing the wheel...).
B. What is the range of a 8266? 50ft? 100? 500?
a. can an external antenna be attached?

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By rudy
#71701 Also consider that if using up all the battery's charge (deep discharge) as a normal situation it will shorten the battery's life.
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By schufti
#71711 a) you don't have to be allways-on.
just start the ESP when mail "drops-in", connect to wifi, send your msg, power off
either via "latching" logic on CHPD pin or "deep sleep and rst"
b) use an LiFePO4 cell, it can directly be connected to ESP as the nominal voltage ~3.3V (3.6-3.0V), is the specified operating range of esp. Charging of LiFePO4 ist quite simple and not critical. For solar panel a typical "crow bar" regulator (@~3.45V) by-passing the excess energy will do.
With only few events a day even a Lithium primary cell will suffice for > 1year.
c) depending on the material of your PB you may find external antenna necessary
d) use some module without on board usb/serial and 3.3V regulator chip. They usually are cheap and eat away on your battery even if cpu is in standby.