Today, I'm going to show you an ESP32 that comes with a battery holder. This works as an energy source for a microcontroller during a power outage. I really enjoy this tool, called in English a “battery holder.” This ESP32 model has load management, which means it has a chip inside it that manages the loading. Therefore, in the moment when the energy source stops, this chip directs the power supply to the battery. See the video:

Step 1: Specifications:

Operating voltage: 2.2 to 3.6 VDC

Built-in antenna

Ultra low-power consumption

Hardware battery charge management

32 GPIO: ADC (16), SPI (2), I2C (1), UART (1), PWM (32), SDIO (50 Mhz)

520 KB SRAM

16 MB Flash

WiFi 802.11BGN Transceiver maximum data rate: 150Mbps

Battery Support 18650

Step 2: Pinning

Here, we have the pin map diagram of an ESP32, and a photo of a Wemos ESP32.

Step 3: ESP32 on the Battery Side

This image shows the bottom of the battery. I placed the four screws in the corners so the assembly looks like a small table, causing it to stand. This wouldn’t be possible without the legs of the screws due to the battery shape.

Step 4: Where Can We Use This?

From another angle, we see a normal ESP. The difference is that it has an on and off button, which is an extra feature that draws attention to this hardware.

Step 5: Application Example for the Wemos ESP31 Battery Holder

Telemetry with ESP32 and DHT22

In this part, I bring up an example application for this device: the telemetry with ESP32 and DHT22. In the case, I have the following situation: the other day a friend wanted to monitor data from a CPD (Data Processing Center), as extreme temperatures in this type of place are capable of causing damage, perhaps burnt out equipment in some situations. So he wanted his ESP to send a warning to him in case of situations that involve a faulty air conditioner or heater, or a power outage.

To not depend on a router or WiFi in such situations, it is best to use an ESP32 with battery support and record your data in the memory of the device. When the server connection is reestablished, this data (taken by the ESP) will be directed to the CPD again.