I have a Schecter Stage-5 that I love and although I haven't had any trouble with it "eating batteries," reading this got my attention. So, I decided to test mine to know for sure if it was a potential problem or not.
Here is what I found. The Stage 5 uses the battery whenever a guitar cord (2 conductor/tip-sleeve/unbalanced) is plugged into it, thereby making a connection to the battery through the "ring" and "sleeve" connections in the jack. Pulling the Volume knob up for the Passive mode does NOT disconnect the battery.
Back to the life of the battery--I measured the voltage drop every 30 minutes with a cord plugged in and the volume turned all the way up (worst case scenario as I would never use it that way due to the extremely hot output). The two new alkaline batteries each started at 9.6 volts and the voltage dropped by 0.02 (two hundredths) of a volt/battery every 30 minutes for the 5 hours that tested it.
I did not drain the batteries to the point of failure; so, I don't know exactly how long that would take. And, the brand/type of battery may yield differing results. However, on the conservative side, assuming that it should be good for at least a 1 volt drop to 8.6 volts (or probably even lower), the battery under maximum usage conditions should last for at least 25 continuous hours.
That is probably less than a lot of other basses; but, considering the powerful preamp, it may not be too bad and I can live with it for the quality of the sound. I will also be unplugging the cord from the bass whenever it is not being used.
I would appreciate any other input that others may have based on their experience.