I’d like to use two xiao nrf52840’s to power a wireless split keyboard. Someone suggested using HAC-006 lion’s to power the boards. (3.7V 525mAh 1.9W). can I simply solder the batteries to the + and - battery spots on the back of the xiao and will the xiao then recharge the batteries if I plug them in to usb? I got a little nervous when I saw a note about batteries/charging/burning out the board.
I’m only using the gpio pins in digital mode to read the keyboard matrix.
The Xiao nRF52840 board does not have built-in battery charging circuitry, so you cannot directly connect the batteries to the + and - battery spots on the back of the board for recharging. Doing so could potentially damage the board or the batteries. You will need a separate battery charging module.
Doesn’t the xiao nrf’s web page says it does battery charging.
Elaborate Power Design: Provide ultra-low power consumption as 5 μA in deep sleep mode while supporting lithium battery charge management
Can anyone else speak to this?
From the Web site,
Features
Versatile Microcontroller: Incorporate the Nordic nRF52840 chip with FPU, operating up to 64 MHz, mounted multiple development ports, supported by Arduino / CircuitPython
Wireless Capabilities: Implement Bluetooth 5.0, BLE functions with onboard antenna, also provide NFC connectivity
Elaborate Power Design: Provide ultra-low power consumption as 5 μA in deep sleep mode while **supporting lithium battery charge management**
Thumb-sized Design: 21 x 17.5mm, Seeed Studio XIAO series classic form-factor, suitable for wearable devices
Perfect for Production: Breadboard-friendly & SMD design, no components on the back
Seeed Studio XIAO nRF52840 has an ultra-low power consumption of only 5 μA in the deep sleep mode, **the embedded BQ25101 chip supports battery charge management** which prolongs its use time. Moreover, Seeed Studio XIAO nRF52840 supports the USB Type-C interface which can supply power and download code. It also has rich On-chip Memory of 1 MB flash and 256 kB RAM, and an Onboard Memory of 2 MB QSPI flash. There are 11 digital i/o that can be used as PWM pins and 6 analog i/o that can be used as ADC pins. It supports UART, IIC, and SPI all three common serial ports. 1 Reset button, 1 3-in-one LED, 1 Charge LED, and 1 Bluetooth antenna are on board, allowing developers to debug their code very easily.
and here is the link to the charge controller[Preformatted text](https://files.seeedstudio.com/wiki/XIAO-BLE/BQ25101.pdf) chip.
HTH
GL 
PJ
No , I believe he is saying that type of battery maybe won’t work in present form?
He can comment , I’ve been using 3.85 LIPO connected without issue for months. Recharging from USB-C power bricks and Charge adapters. No issue’s I monitored it the first time with a USB amp meter and watched as it topped up and didn’t over charge. (pic’s are on here)
HTH
GL
PJ
