ESP8266 Thing Hookup Guide
jimblom 
Powering the Thing
The Thing provides for two methods of power delivery: USB or LiPo. The USB connector on the Thing is of the Micro-B variety. A micro-B cable plugged into either a computer USB port or a 5V USB Wall Wart can power the Thing.
Any of our single-cell LiPo batteries will also work to power the Thing -- they all have the same 2-pin JST connector.
If both USB and LiPo are connected to the Thing, it'll take power from the USB port and charge the LiPo battery at up to 500mA.
Electrical Characteristics
The ESP8266's maximum voltage is 3.6V, so the Thing has an onboard 3.3V regulator to deliver a safe, consistent voltage to the IC. That means the ESP8266's I/O pins also run at 3.3V, you'll need to level shift any 5V signals running into the IC.
The input to this regulator can either be delivered by USB, LiPo battery, or through the VIN pin.
Alternatively, if you have an external, regulated, supply you'd like to deliver directly to the ESP8266, you can supply that voltage through the 3V3 pin (on the I2C header). While this voltage doesn't have to be 3.3V, it must be within the range of 1.7-3.6V.
Current Ratings
On average, the Thing pulls about 80mA. WiFi transmits and receives can momentarily increase that draw. Here's a table, transcribed from the ESP8266 datasheet, with some of the more common current characteristics.
| Parameter | Typical | Max | Unit |
|---|---|---|---|
| Transmit 802.11b (1 Mbps) | 215 | mA | |
| Transmit 802.11b (11 Mbps) | 197 | mA | |
| Transmit 802.11g (54 Mbps) | 145 | mA | |
| Transmit 802.11n | 135 | mA | |
| Receive 802.11b | 60 | mA | |
| Receive 802.11g | 60 | mA | |
| Receive 802.11n | 62 | mA | |
| Standby | 0.9 | mA | |
| Deep Sleep | 10 | µA | |
| Maximum I/O Pin Drive Capability | 12 | mA |
If your application requires maximum battery life, you'll likely need to make liberal use of the ESP8266's deep sleep functionality. That'll be covered later in this tutorial.