It sort of depends on how much power you need (how long you need to run and how much power is needed at any particular point in time), what kind of form factor you want to use, whether you want the battery to be rechargeable (either in place, or by removing the battery, etc.).
The simplest approach is to use a cell phone charger battery that can deliver 5v via the USB cable. If you aren't going to power a lot of LEDs or motors, these batteries often can deliver 500mA of power.
Alternatively, you can use a lithium poly battery, and just connect it to ground and VIN. The li-po battery delivers 4.2-3.7v, which the Teensy will work with. If you are doing some LEDs (ws2812b/neopixels or apa102/dotstars), the 3.7v is within the lower bounds of the power needed. If you don't do any modifications to the Teensy, you have to make sure you don't connect the battery and the USB at the same time. You can cut the trace between VUSB and VIN (https://forum.pjrc.com/threads/1922...ng-VIN-from-VUSB-Teensy-3-0?p=44024#post44024) which means the Teensy has to be powered by external power. FWIW, I've run for about 24 hours from a 1200mA li-po battery, with the processor and 16 LEDs (note, power level of the LEDs was tuned down). The 1200mA battery I used (https://www.adafruit.com/products/258) is roughly Teensy sized.
Onehorse has a board you can solder underneath the Teensy (https://www.tindie.com/products/onehorse/stbc08-high-current-lipo-battery-charger/) that allows you to charge the li-po battery from USB, and if USB is not connected, it runs off of the battery (you will need to cut the VUSB/VIN trace and solder the board to the Teensy). If you don't get something like Onehorse's board, you will need to get some method of charging the li-po battery.
If you have rechargeable AA or AAA batteries lying around, you can wire up a 3 pack of AA batteries to VIN/ground. A 3 pack of batteries would deliver 5.1-3.6v.
If your batteries are variable in voltage, or you want to use different batteries at different times, you can get a buck/boost converter that will boost 3-5v up to 5v or reduct 5-12v to 5v (https://www.adafruit.com/products/2190). Note, this particular converter is better at reducing voltage than boosting it.
It sort of depends on how much power you need (how long you need to run and how much power is needed at any particular point in time), what kind of form factor you want to use, whether you want the battery to be rechargeable (either in place, or by removing the battery, etc.).
The simplest approach is to use a cell phone charger battery that can deliver 5v via the USB cable. If you aren't going to power a lot of LEDs or motors, these batteries often can deliver 500mA of power.
Alternatively, you can use a lithium poly battery, and just connect it to ground and VIN. The li-po battery delivers 4.2-3.7v, which the Teensy will work with. If you are doing some LEDs (ws2812b/neopixels or apa102/dotstars), the 3.7v is within the lower bounds of the power needed. If you don't do any modifications to the Teensy, you have to make sure you don't connect the battery and the USB at the same time. You can cut the trace between VUSB and VIN (https://forum.pjrc.com/threads/1922...ng-VIN-from-VUSB-Teensy-3-0?p=44024#post44024) which means the Teensy has to be powered by external power. FWIW, I've run for about 24 hours from a 1200mA li-po battery, with the processor and 16 LEDs (note, power level of the LEDs was tuned down). The 1200mA battery I used (https://www.adafruit.com/products/258) is roughly Teensy sized.
Onehorse has a board you can solder underneath the Teensy (https://www.tindie.com/products/onehorse/stbc08-high-current-lipo-battery-charger/) that allows you to charge the li-po battery from USB, and if USB is not connected, it runs off of the battery (you will need to cut the VUSB/VIN trace and solder the board to the Teensy). If you don't get something like Onehorse's board, you will need to get some method of charging the li-po battery.
If you have rechargeable AA or AAA batteries lying around, you can wire up a 3 pack of AA batteries to VIN/ground. A 3 pack of batteries would deliver 5.1-3.6v.
If your batteries are variable in voltage, or you want to use different batteries at different times, you can get a buck/boost converter that will boost 3-5v up to 5v or reduct 5-12v to 5v (https://www.adafruit.com/products/2190). Note, this particular converter is better at reducing voltage than boosting it.
I've used this Boost Converter successfully to run my Teensy POV Project off a LiPo battery. It may be a little over kill, but the converter gives a nice strong +5V for the APA102 LEDs and it can recharge the LiPo with a USB cable.
Perhaps not. I was answering the question in the title of this thread: "Teensy 3.2: powered by battery. How to?"Hmmm, I'm not sure if this will solve my grounding problem.