Every child who grew up in the 1980s and early 1990s remembers that distinctive, slightly sour and tingling taste on their tongue. Before the advent of rechargeable gadgets and built-in testers, checking an ordinary battery required a rather unconventional method – touching it directly to the tongue.
Although it sounds absurd and even dangerous today, for the generation of the 1980s this was a perfectly normal practice. But what was the actual reason?
The Household „Multimeter“
The main reason was purely practical. In the 1980s, almost no one had a voltmeter or a special battery tester at home. When the radio, Walkman or remote-controlled car stopped working, the only quick way to find out whether the problem was the battery was to use your tongue.
Saliva is a good conductor of electricity. When the tongue touches both terminals at the same time, a weak electrical circuit is completed. If the battery is fully charged, a small current flows, irritating the taste buds and creating the characteristic metallic tingling sensation. If you feel nothing – the battery is ready to be thrown away.
Why 9-Volt Batteries in Particular?
This „test“ worked best with square 9-volt batteries. The reason lies in their design. Unlike standard cylindrical batteries (AA or AAA), where the positive and negative terminals are located at opposite ends, the two contacts on 9-volt batteries are positioned next to each other on the top. This made touching them with the tongue extremely easy and convenient.
Curiosity and Childhood Challenges
Besides the practical side, there was also an element of play. The strange, tickling sensation was fun for children and often became a test of courage in front of friends. The newer the battery, the stronger the „sting“, which provoked laughter and grimaces.
Was It Safe?
The 9-volt voltage is too low to cause a serious electric shock in a healthy person, since dry skin has high resistance. A wet tongue, however, significantly reduces that resistance.
Although the risk of serious injury is minimal, doctors warn that this habit is not entirely harmless. Holding the battery against the tongue for too long can cause a minor burn, while older or damaged batteries pose a real risk of toxic chemicals and heavy metals leaking directly into the mouth. Today, such experiments are merely a funny nostalgic memory from a more analog childhood.