Need clarification on the two 3.3V power output ports and the Vin port

[teensy_teen]

Hi, according to the Welcome to Teensy 4.1 card that came with the board, there are two 3.3V. The one above A10 on the left is 3.3V while the one above A9 on the right is 3.3V (250 mA max). For the one on the left, what is the maximum current that it can provide to breakout boards? Is it better to use this one than the one on the right as it probably can offer more current? As for the Vin port, what is the recommended and maximum allowable current input in mA if I use 3.7V LIPO battery?

 

[grease_lighting]

If the T4.x series is anything like the T3.x series, then those pins marked 3.3v are common (the same). They supply up to 250mA total current (I1 + I2). Check the schematic on the website. https://www.pjrc.com/teensy/schematic.html

You will also see on the schematic that the USB & Vin input is fused for 500mA. That would be the maximum allowed input current, although electronics only takes what it needs which is usually less. That would depend on how much additional circuitry is added to it.

Also if you are using a LiPo battery then you would need a means to charge it properly. Many such devices are available on Tindie and AdaFruit.