Feeding power back into a PowerBoost

[tangrs]

Is the PowerBoost designed to have power fed back from the USB output?

I am planning to connect a LiPoly battery through a PowerBoost via jumper cables directly to the 5V rail on a Raspberry Pi and was wondering if there would be any damage if the user decides to plug in a USB charger and potentially feed current backwards into the PowerBoost.

[adafruit_support_bill]

No that is not a good idea: https://learn.adafruit.com/adafruit-powerboost/pinouts

5V - this is the boosted output. When the board is running, the voltage will be 5.2V approximately. It may dip down to 5V as the current draw starts to go up (over 500mA). When the board is disabled, this output is 'floating' but you should still try not to apply a voltage to it while the board is disabled. There's a green LED connected to this pin which will let you know when there's power output

[zener]

The issue is the TI part can only take 7V "ABSOLUTE MAXIMUM" on that pin. Since you probably can't guarantee various USB devices might not go over that, that is the reason. If you go over that it could be "hasta la vista baby."