Help with Connecting Lipo Battery and Charger to Teensy 3.2

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lerxstrulz

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Hi All,

I'm using a Teensy 3.2 with the Audio Adapter and am wanting to power it with a Lipo battery and accomplish the following:

1. Micro USB is used to program Teensy as normal
2. Micro USB is used to charge Lipo battery
3. Micro USB can still be used to power Teensy

I am piecing information together from several sources:

1. Using External Power and USB
2. Use an Adafruit LiPoly/LiIon Backpack Charger with a Teensy

Attached is a pic of how I think it needs to be connected.

Do I still need to use the diodes as described in "Using External Power and USB"?

Thank you!

teensywithlipo.jpg
 
The diodes are if you want to support power from battery or USB. In this case I think your battery charge module can already do that can't it (output 5V while charging)? So the diodes would be an extra complication and mean your 5V was actually ~4.5.

Wiring show looks right, though there are spare through holes for VUSB(to charger), and gnd, and since the audio board doesn't use 5V you could bend or removed the pin for the from charger wire. Optional but idea is to maximise the strength of the connections over just going to an surface pad that might peel off.
 
I happen to have that same LiPoly adapter.

Here is my setup:
IMG_0489.jpg

The black wire is from "G" to Teensy GND.
The red wire is from Teensy VUSB to adapter "5V".
Adapter's BAT is connected to Teensy VIN directly via the breadboard.

Note: the pinhole between AGND and the USB connector is VUSB, so you don't have to solder to the bottom pad if you don't want to.

Edit: And the underside VIN--VUSB trace is CUT, off course!

The power switch goes to the adapter, so it doesn't change any connections described above.

Also, the Audio board should not change anything, you just stack it with the Teensy.
 
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Ah, go with Pazi's answer, I misread the tabs on the PCB as a pass through charger. What happens wired like that if you pull the USB with things running? Does the boost circuit take enough time to kick in that things fall over, or does it pick up fast enough to not notice?
 
GremlinWrangler said:
What happens wired like that if you pull the USB with things running? Does the boost circuit take enough time to kick in that things fall over, or does it pick up fast enough to not notice?
Click to expand...
Just tested. You can pull the USB and plug it back, and the program just keeps running :)

However, there seems to be no boost circuit. I measured the BAT voltage. It was 3.99V when loading, and a little less when unplugged. Seems to be enough to keep T3.2 running though. Teensy should run even when it drops to 3.7V.
 
GremlinWrangler said:
The diodes are if you want to support power from battery or USB. In this case I think your battery charge module can already do that can't it (output 5V while charging)? So the diodes would be an extra complication and mean your 5V was actually ~4.5.

Wiring show looks right, though there are spare through holes for VUSB(to charger), and gnd, and since the audio board doesn't use 5V you could bend or removed the pin for the from charger wire. Optional but idea is to maximise the strength of the connections over just going to an surface pad that might peel off.
Click to expand...

Awesome thank you! And yes good idea I will try that.
 
Great guys thanks for the responses. Seems easy enough...just didn't want to fry the Teensy ;) Thanks again, going to wire it up today.
 
Some observations:

- When the load (i.e. Teensy, a display, leds etc) is in place, the indicator LED stays red and never turn green. You'll need to disconnect the load, to see if the battery is fully charged or not. (That power switch will be handy.)
- The BAT pin is directly connected to the battery, so there is no protection circuit there. So this relies on the protection circuit built in the battery itself. This should be no problem though, as long as good quality batteries are used.

Tip: if your battery is 500mAh or more, close the solder jumper to get 500mA charging current. So your battery charges quicker!
 
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