The 175 year old battery that is still going … and going …

How long did your last disposable battery last? “Not long enough” is probably your answer. So what would you say if you knew that tucked away in a British University, covered by two glass domes to muffle its incessant ringing, is a bell that has been chiming since 1840 … and its battery has never been replaced?

Everlasting power forged in the Victorian age?

The Oxford Bell
The Oxford Bell has chimed over 10 billion times and its battery has never been changed.

The entire contraption was built around 1840 (some say earlier ) by the London based firm Watkins and Hill. One of the partners, Francis Watkins, had developed a keen interest in the new inventions of electricity and magnetism that were revolutionizing the industrial age and came up with the design as part of his own experiments.

40 years earlier Alessandro Volta had invented the first battery by placing copper and zinc discs on top of each other and separating each pair with a brine soaked piece of cloth. Despite being a major breakthrough in creating portable power as a concept it was weak, lasted less than an hour and leaked messy and damaging liquids.

Francis Watkins was one of many inventors in an age of industrious Victorians searching to perfect and improve Volta’s work.

This said, there is plenty to suggest that Watkins regarded his own endeavors  as little more than a hobby with his company listing itself as ‘ Opticians and Philosophical Instrument Makers’. Optical products were their main line of business while other contraptions were, well, philosophical concepts to toy with.

Around 1850 Robert Walker, a Physics Professor at Oxford University purchased the battery powered bell from Watkins and Hill. He wrote ‘Set up in 1840’ on a small piece of card as a reminder and placed it with the device. It remains there to this day.

Robert Walker died in 1865, but the bell rang on and still does so, clocking up 10 billion chimes and growing.  It now holds the Guinness Book of Records title for ‘most durable battery’.

How does it work?

The Oxford Bell is actually two brass bells, each with a battery above them. In between the bells hangs a metal spherical clapper four millimeters in diameter. As the clapper makes contact with a bell the battery above gives off a small electrical charge repulsing it and pushing it towards the opposite brass dome.

The actual movement of the clapper is tiny as can be seen in the video below, even in the close up that starts at 0:23 it is not always obvious to see the clapper in motion.

Despite the small amount of power needed to achieve this, it is still impressive as no other battery has ever been able to power anything for so long. Batteries, even when not in use, slowly discharge and most will have completely drained themselves within a few decades, some within a matter of years.

The batteries that power the Oxford Bell on the other hand have been in almost non-stop operation for nearly two centuries.

Why don’t we use this technology?

Unfortunately Francis Watkins did not leave any documents revealing how his batteries were constructed. At the same time scientists are reluctant to touch it until the bells stop ringing. They want what Mental Floss has dubbed ‘The World’s Longest Running Experiment’ to reach a natural conclusion before opening up the structures.

The only fact that is known for certain is the sulfur outer coating material, popular in the early 1800’s as a method to stop electrolyte leaking or evaporating.

Beyond this there is just speculation. Some believe each one is made up from thousands of discs of tin foil glued to paper (the separator) coated in manganese dioxide and with just enough water to provide a working electrolyte solution.

These discs were piled on top of each other to create column like structures. The sulfur coating stopped the water from leaking or evaporating and so, unlike Volta’s original design, it is referred to as ‘dry pile’.

But such guesswork is simply based on how other batteries of the time were made, especially a popular ‘dry pile’ version invented by Giuseppe Zamboni in 1812.

It’s an educated guess although at around the same period people were also experimenting with all sorts of other materials including piles made up of walnut wood, beetroot slices and radishes to name but a few of the more bizarre combinations.

No other dry pile battery has ever lasted this long, so Watkins must have added a twist to Zamboni’s design, even if he didn’t realize it at the time.

Will we ever discover the Oxford Bell’s secret?

The Oxford Bell is open to public view in the foyer of the Clarendon Laboratory at Oxford University and has become somewhat of a tourist attraction, so if you do drop in to get a photo, expect to find a bit of a line.

With no end in sight, some enthusiasts have even set up new experiments such as the one below which was started in 2014. However, If these are any where near as successful as the original, they will easily outlast their inventors.

When it comes to uncovering the mystery of what truly powers the Oxford Bell, it looks like we will just have to wait until the batteries are exhausted or the clapper wears out (which some think more likely).

Further reading and sources

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