I sometimes get severe battery drops after rebooting, but it's getting less frequent. As Hawker said, it starts rising after that and eventually catches up with the number it's meant to be.
Random reboots due to the sd card point to an incompatible sd card. What brand is it? If it's not sandisk, try a sandisk one. If it's sandisk, there's something more serious wrong.
SGS4: Stock ROM, rooted w/ CF-Root
HP Touchpad: CM9 tenderloin 28-Apr-13