One universal phenomenon observed by ghost hunters is the weird behavior of technology in the presence of the paranormal. Batteries drain and go dead. Audio recorders fail and equipment malfunctions. In a practical sense, this means backup batteries and equipment are always needed to ensure that the phenomena that causes the equipment to fail can be recorded in some way.

If we accept at face value the statement that paranormal activity causes equipment failure, we then have to come up with a hypothesis as to what is actually going on. It also means that you should always bring along some sort of nontechnological means of seeing in the dark, even if it is something as low-tech as matches and candles.

There have been countless reports of appliances, televisions, and computers being turned on by unseen hands, sometimes even when they are unplugged. But sometimes there is a simple explanation for this, as walkie-talkies have been known to act like remote controls and turn on televisions.

Grant Wilson from TAPS explained his theory about all this in one episode of Ghost Hunters. When the paranormal activity at a site is really hot, the entities who are trying to manifest will draw energy from the air around them, causing sudden temperature drops or drained batteries. Sometimes the people in the vicinity will also be overcome with great fatigue and tiredness, as if something is draining them.

Another theory goes that increased electromagnetic field activity and positive ionization (static electricity) are present at most active paranormal sites. Most of today's digital devices use nickel-cadmium rechargeable batteries, and the battery manufacturers warn that these batteries are extremely susceptible to both electromagnetic fields and static electricity.

Occasionally, there have also been odd reports of batteries operating for far longer than they should or even cases of electrical meters running backward. These may be instances of entities trying to give energy back rather than take it.

It isn't only battery drain that stops investigators' work. Occasionally, cameras will work, but a strange blurry effect makes all the images look surreal. This is puzzling to experience, especially to seasoned photographers who know what to expect from their cameras under all sorts of lighting conditions.