It is common speculation among paranormal investigators that ghost drain batteries. From my own experience, I have found it more likely that I placed a weak battery from a fresh pack. I have witnessed ghost hunters say this several times; “I just put fresh batteries in this.” Don't trust a battery all because you pulled it from a fresh package. As part of your investigation preparation, measure the voltage of all your batteries. The voltage of a new battery should be between 1.5 to 1.65 volts. You will be surprised how many weak batteries you will find when you start checking. Also, do not throw away your used batteries. If you suspect that a ghost has drained your batteries, measure their voltage. Most electric devices will cease to function if the battery voltage drops to around 1.3 volts. If the battery is completely drained, 0 volts, then suspect a ghost. If the battery voltage is around 1.3 volts, then suspect high power drain from your electronic device.
P.S. A good thing to carry in your ghost hunting kit is a battery tester. One can be purchased at Walmart for under $5.