I'm planning to connect raspberry pi to DAGU mini driver, just as shown here. I have a question regarding the minidriver drawing current from the Pi USB port. As far as I know if there is no battery connected, then it draws current from USB connection and that wouldn't be nice for a Pi with its weak USB power. However, when the battery is in, can it be considered safe? And if so, can it still be safe if for example, battery connector suddenly plug off leaving minidriver only connected to a Pi (and the minidriver could be then trying to drive motors)?