ESP8266 Community Forum

- Sun Jul 05, 2015 11:00 am #22487 This youtube video showed an application an Arduino can run for more than a year (mostly sleeping):
https://www.youtube.com/watch?v=TEr-ora ... 5atfch3zdy

It seems that using D mono cells it could run for more than 4 years (see comment).

How long could such a project based on ESP8266 instead of Arduino run?

Hermann.

- Sun Jul 05, 2015 1:42 pm #22503 Depends on your application. You must account for ESP and the sensor current to arrive at the duration. Some sensors like MQ135 needs heating time @ 150mA to sense the air quality before it provides a decent reading. While others like BMP180 are instantaneous. I connect one of the GPIO pin as power supply to sensor, set it HIGH, take reading and put the node to deep sleep. Once an important event is observed (or sufficient data points are collected), I upload the data to a server.

You can refer to my earlier post viewtopic.php?f=13&t=3875 for some typical use-cases. You can then postulate the duration based on battery capacity.

FYI, in one of my autonomous garden watering application I use 12V 10A (UPS) battery with a high efficiency 5V buck converter for 5V circuitry and the usual LM1117 3.3V for the uC. The water pump comes on every alternate day for a minute or so. I haven't touched it for 3 months now. I am hoping an years worth of service, provided the flipping wasps stop constructing their nests in the circuit box

In short, unless you apply smart sleep/wake strategy your batteries wont last long.

- Sun Jul 05, 2015 7:05 pm #22532

the usual LM1117

There is no such "usual" thing. I have some '1117's that leak 3mA while others take as low as 50uA. One needs to carefully select the LDO.

And when we talk "years" we need to account for the battery self discharge, which can be very high for some types.

- Mon Jul 06, 2015 10:00 pm #22650 The lowest current LDO that I've found is the Microchip MCP1700/1702 series. They only use about 1uA when idle and can deliver 250mA from a TO-92 package. I use them to supply 3.3V to a board with an XBee radio, ATtiny84 controller, and CHIPCAP2 temp/humidity sensor. The entire board only uses 18uA when the XBee, ATtiny, and sensor are sleeping. Powered by three Energizer Ultimate Lithium AA batteries, which have a shelf life of 20 years!

-Jeff

TempHumiditySensor_BatteryBox3.jpg

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