Currently I use a 1000mAH 3.7v li-po li-po with my Thing Plus (SAMD51). Assuming it’s fine for the power requirements of my project, can I use a smaller battery, like a 400mAh or 110mAh 3.7v li-po?
Minimum would depend on how long you want the device to operate, it’s safe to go down to 50mAh if you wanted. The lower your capacity, the less run time you will have.
If you’re planning on charging a battery with the board, that’s where you could run into trouble. If you plan to charge batteries with the board, don’t go below 500mAh so that the charger in the board doesn’t burn up your battery.
Thanks! Yes, my concern was mostly with the charger (and/or other potential safety issues with going with a smaller battery). Sorry, I should have made that clear.