ESP8266 Community Forum

- Sun Feb 12, 2017 5:14 am #62436 I have very basic understanding of circuit design, but I would to know a simple way to open/close a circuit using a ESP-12E Node MCU board.

I've used digitalWrite to send a GPIO high and low to turn a simple led on/off but i'm not sure I'm can use the same method for higher voltages, in this case 5V solar panel.

Should i be using a relay and if so are 3.3v relay around. This is abattery powered project so i want to conserved battery life.

Thanks in advance.

- Sun Feb 12, 2017 8:48 am #62442 Have a look at this :-
http://www.ebay.co.uk/itm/3V-3-3V-Relay-High-Level-Driver-Relay-Module-for-Arduino-Optocoupler-u-/231535394504?hash=item35e895bec8:g:sAIAAOSwrklU~9TL
All it requires is 3.3v, gnd, and a control signal from your ESP.

- Sun Feb 12, 2017 9:02 am #62443 Since this is a battery powered project you would probably be better off with a semiconductor switch rather than a coil driven relay. A relay consumes more power.

My first choice would be to use a mosfet to switch the power. I would need more details about what you want to do in order to give you a better answer.

- Tue Feb 14, 2017 2:18 am #62542

Since this is a battery powered project you would probably be better off with a semiconductor switch rather than a coil driven relay. A relay consumes more power.

My first choice would be to use a mosfet to switch the power. I would need more details about what you want to do in order to give you a better answer.

I have the esp8266 monitoring the battery SOC with a LTC4150. This will be be connected to TP4506 that has the lipo and solar cell connected to it. I'd like keep the circuit for the solar cell disconnected until the SOC reaches a defined level to ensure the lipo decent discharge before recharge