You can tell whether the battery is new by dropping it

It is said that there is a simple test method to determine whether a battery has power: drop the battery on the ground, and the dead battery will bounce up. But this method has always been somewhat skeptical, and many people believe that it has no scientific basis. Now, a study by researchers at Princeton University in the United States has finally put the matter to rest. The research report has been published in the British Journal of Materials Chemistry.

The study proved that the more power a battery uses, the higher it can jump. During the measurement, the researchers dropped the batteries from a plexiglass tube and recorded the height they bounced. After half of the battery's power was used up, the bounce height tended to stabilize.

Most disposable batteries consist of two parts: a negative electrode containing manganese dioxide, and a positive electrode containing gelatinous zinc and some potassium hydroxide—the same alkali that gives standard, non-rechargeable alkaline batteries their name.

When the battery's two terminals are connected, the zinc reacts with the hydroxide at the positive electrode, releasing electrons that flow to the manganese dioxide at the negative electrode, thereby generating electricity. During this process, various chemicals react to form zinc oxide and another form of manganese oxide. After all the zinc has reacted, there is nothing left to generate electricity, and the battery is dead.

The gelatinous material in the battery slowly hardens as zinc oxide forms around the zinc particles. The material starts out as tightly packed particles, but the oxidation process forms tiny bridges between the particles, creating a material that acts like a set of connected springs, allowing it to bounce.

However, the battery reaches its "maximum bounce height" when half of its charge is used up - even though more zinc oxide is still forming in the battery, its bounce height has stabilized.

Therefore, the bounce test method can only prove whether the battery is new, but it cannot indicate whether the battery is completely discharged.

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.