Every flash cart i've had on the ds has drained the battery quickly in stand-by mode.
my theory is that the flash cart draws more power than a stock cart due to the microSD card. *shrug*
I just today got my DSTT from DX (to upgrade form my r4). Seems to have all the same markings as a fake - however i cannot stress this enough - it did not arrive in this new packaging shown on the DSTT site.