hello, I’m a little confused on the usage of LiPo batteries and I want to ask if I can use a LiPo of 3.7 V of 500 mAh on the Seeeduino Xiao, I read that it used 3.3V or 5V but I’m not sure if need to use a resistance to drop the 3.7V to 3.3V, also I don’t know which tags to use.
The VIN pad on the bottom of the XIAO is connected to the input of the voltage regulator. The regulator is an LDO regulator with a minimum differential of 250mv so you can use a LiPo battery down to ~3.5 volts. Obviously not a complete discharge but depending on your application (i.e. are you using sleep) it could last a long time. Removing the power LED (can make it last a really long time). Obviously you will need a battery charger. Incidentally this is exactly what I will be doing for a kitchen timer that will be sleeping most of the time and awakened with a button.
If you connect the USB cable while the battery is connected to the VIN, the battery will be charged without current control, so you should be careful.
I’m trying to accomplish something similar, would you care to explain a bit more?
Do you mean the battery would get charged over capacity? Is this still true if I use the contact pads on the bottom of the device?
A VIN pad and a VCC pin are connected inside a XIAO, and 5V supplied from PC’s USB port is directly output. Connecting a battery directly here is dangerous because a XIAO does not control charging. There is a possibility that a large charging current will flow, causing the temperature to rise or a battery to be charged above 4.2V.
Cheers for steering me in the right direction.
For anyone wondering I got this working with a TP4056 by wiring the 5v and GND pins out to the VIN and GND respectively on the TP4056 then wiring the OUT+ side to a simple on/off switch and then from there to the 3v3 on the board, and likewise the OUT- to the GND pin on the Xaio. B+ and B- go to your battery connector. Makes for a really handy “safe” rechargeable lipo circuit on one USB port. The on/off switch is optional and the battery will still charge when the Xaio is plugged in via USB. You can also accomplish this without the 5v to the VIN on the TP4056 if you don’t mind using a different port for charging/programming, personally, I just removed the USB port on the TP4056 to save space in my enclosure.
hey defroh, this sounds really awesome and I’m interested in trying to incorporate this also, is there any chance you have a circuit diagram you could share to help us plebes?
EDIT: Perhaps I’m also confused, but when I look at the schematic for the BLE Sense, it seems it already comes with a LiPo battery charging chip:
I’m pretty new to this stuff so any help would be very appreciated.