ESP8266 Community Forum

- Wed Jan 20, 2016 2:52 am #39280 Hi,
I am trying to make a temperature monitor unit using ESP-12 and DHT11. Module is powered using 2xAA batteries (Energizer with 2500 maH) and programmed to send the temperature measurement in every 30 minutes to the server. I am using deepsleep to save the battery power. Unit is working perfectly.

But battery power lasts only for 8 to 9 days and the unit is not working after that. As per my calculation based on power consumption, the module should run for 50 days)
How i can further increase the battery life like 3 to 4 months. (Even without DHT module also, the battery power drains after 9 days)

Or anybody tried any circuit with ESP using battery which works more than 3 months ( using 2xAA batteries or any other type).

Any reply is appreciated.

- Thu Jan 21, 2016 6:11 am #39353 Hi !

two month ago I've launched two boards (ESP12 + DS18B20 + LifePo4 1500mAH battery)

The first , still running, sends temperature and battery voltage to ThingSpeak, intervall = 6 minutes.
The second (more than 6 months expected, including battery's self-discharge !!) sends same datas with 1 hour interval.

LifePo4 (3.2V) battery allows direct powering and good current pulses feeding + no regulator needed.
Strong pull-ups added to have 100% wake-up from deep-sleep
Time out added to skip data sending (return to deep-sleep) if AP or ThingSpeak server not answering after 30 seconds.

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- Thu Jan 21, 2016 8:42 am #39359

Hi !

two month ago I've launched two boards (ESP12 + DS18B20 + LifePo4 1500mAH battery)

The first , still running, sends temperature and battery voltage to ThingSpeak, intervall = 6 minutes.
The second (more than 6 months expected, including battery's self-discharge !!) sends same datas with 1 hour interval.

LifePo4 (3.2V) battery allows direct powering and good current pulses feeding + no regulator needed.
Strong pull-ups added to have 100% wake-up from deep-sleep
Time out added to skip data sending (return to deep-sleep) if AP or ThingSpeak server not answering after 30 seconds.

Thanks for your response. I will try with the LiFePO battery and check the life.
I was using Energizer E91 2XAA battery which has 2500maH. Not sure why it is not running for longer. Did you try with such Alkaline batteries earlier.

- Thu Jan 21, 2016 9:52 am #39363 I'll try good alkaline when one of my boards will stop (later is better !)

Made some previous (less intereresting) tests with some Lipos (from phones or cameras) and several regulators (LDO, buck , buck/boost)

Have you some 'big' and good capacitor (low ESR) between Vss and Gnd ?
Did you try lower TX Power ?

In my case Vss brownout (caused by strong Tx pulses) caused sometimes ESP82266 'bad awake', letting the chip 'warm' in so callled 'zombie mode' , and then short battery life.