For those who like their questions to be 100% practical and serious, please look away now.
I've just watched "Raiders of the Lost Ark", which got me speculating about how to bring the booby-trapped temple into the 20th century. I reckon the first upgrade has to be to provide electricity, but how long can a battery sit on the shelf for and still work?
The longest shelf life battery I can find is a hertz horn these have been used to provide short bursts of power to detonate sea mines. Basically they have a glass phial of acid/electrolyte which when broken open, will cover a set of dis-similar metal plates and produce a small electrical charge. There are occasional stories of these mines being detonated decades after being laid.
Can anyone give me any idea of the likely lifespan of a hertz horn? Are there any batteries with a longer shelf life?
Update - I'm aware that any such battery is a one-time only thing, I was thinking that the battery would be initiated by the heroic explorer/villainous tomb-robber by mechanical means (i.e. treading on the glass phial), the electricity generated would be reserved for powering an entertaining death machine for said hero/villain. To actually detect an intruder electronically would require a power source to continuously work (i.e. remain powered and draw current) for hundreds of years - a different question all together.