The battery connector has a fet between it and... everything else, which allows you to connect USB while using a low voltage battery. You can see the circuit here: http://www.espruino.com/EspruinoBoard
You can supply power using the Bat pins, as long as the voltage on the batteries is >4.7V (at least while USB is connected), so USB won't try to charge the battery (you don't want to charge the battery this way, to be clear). Also, if you do this, you won't have the 1A self-resetting fuse protecting the Bat pins.
If that's not acceptable, and the pads for the battery connector are hopelessly munged, there are unpopulated pads for a resistor R9 (on v1.3) - the pad closest to the connectors is connected directly to the positive side of battery connector. On v1.4, there are pads for a charging IC - one of those pads is also connected to the positive side of battery.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
The battery connector has a fet between it and... everything else, which allows you to connect USB while using a low voltage battery. You can see the circuit here: http://www.espruino.com/EspruinoBoard
You can supply power using the Bat pins, as long as the voltage on the batteries is >4.7V (at least while USB is connected), so USB won't try to charge the battery (you don't want to charge the battery this way, to be clear). Also, if you do this, you won't have the 1A self-resetting fuse protecting the Bat pins.
If that's not acceptable, and the pads for the battery connector are hopelessly munged, there are unpopulated pads for a resistor R9 (on v1.3) - the pad closest to the connectors is connected directly to the positive side of battery connector. On v1.4, there are pads for a charging IC - one of those pads is also connected to the positive side of battery.