This instructables show how to reduce battery power usage while developing unwired ESP based IoT device.
Step 1: Where the Power Goes?
As per my previous measurement in IoT Power Consumption Concern, there are still consuming about 10 mA even ESP entered deep sleep if you are using dev board. Where that 10 mA goes?
Search all over the web you may find some reasons:
- Power regulator, the power source may be USB 5 V or Lipo 4.2 V, it require a regulator step down the voltage to 3.3 V for ESP. Some regulator may consume few mA power in this process, most articles suggest using LDO regulator to overcome this.
- USB to TTL chip always connected in the circuit even you don't need it other than programming. Since it connected the power, it always drain some power.
- Other unnecessary components, e.g. power LED
Step 2: Decouple Dev Component Design
I would like to keep the easy programming of dev board but at the same time reduce the power consumption while using it. How about decouple the dev board component from the ESP device?
Let's split dev board into 2 parts:
- Dev Dock, it include
- USB to TTL chip
- The circuit that convert RTS/DTR signal to RST/program control
- Lipo charge chip
- ESP Device, it include
- ESP board
- Lipo battery
- 3.3 V LDO regulator
While development, connect ESP Device to Dev Dock to enjoy easy programming; After that, remove ESP Device from Dev Dock to make it portable and reduce power consumption.
Step 3: What's Next?
I will squeeze all components to two 3D printed cases build a prototype, I will post the latest news at my Twitter.