Xiao BLE Sense with Li Ion 18650

tinkerwin · October 9, 2022, 8:42am

Hi,

I am using Xiao BLE Sense board with 1x Li Ion 18650 but the board is not power up. I am connecting battery from BAT+/- pin. The unit is fine with USB power. Does anyone has an issue with it or I am doing something wrong? Thanks in advance.

Best regards,

Kyi Zaw Win

Adrian · October 9, 2022, 4:27pm

I think that’s a 3.6 to 3.7 V cell. The XIAO gets 5V from the USB which it converts to 3.3V on board. But the on board converter needs some voltage “headroom” - I think it’s okay with down to about 4.0V but not less.

I wouldn’t connect the 3.7V directly to the 3,3V pin as you might blow it, but I think you could try connecting it via a silicon diode as it probably can run at 3.0V.

You might want to wait for someone who has tried this before and knows the answer for sure!

PJ_Glasso · October 9, 2022, 5:57pm

Hi There, Yes I have used both and they work no issues here.

HTH
GL

msfujino · October 9, 2022, 10:30pm

Kyi Zaw Win,
Have you measured the voltage between BAT+/BAT- when connected to USB and when not connected to USB?

PJ_Glasso · October 10, 2022, 4:19am

Here is what I have when connected and charging the Batt and when the usb is disconnected. I use these 3.7 to 3.85 v batteries 450mah-1100mha. They work perfectly and I recharges very fast.

Typically its 4.08 vdc when plugged in and charging it 4.1 thats with a BLE connected and functioning. Plugging in and unplugging doesn’t drop the connection either.
HTH
GL

tinkerwin · October 10, 2022, 5:56am

Thanks for the prompt reply. I just realized that powering from BAT+/- will have no 5V which make kinda sense that there is no DC-DC converter onboard. The chip is running. Thanks!