Scientific tests confirm batteries bounce when low on charge

But despite initial claims that a bouncy battery is ‘dead’ and should be thrown away, scientists have discovered this isn’t exactly the case.Using a combination of X-rays and lab experiments, engineers confirmed batteries do indeed bounce as they lose charge – but the highest bounce occurs when the battery is half full. Using a combination […]

But despite initial claims that a bouncy battery is ‘dead’ and should be thrown away, scientists have discovered this isn’t exactly the case.
Using a combination of X-rays and lab experiments, engineers confirmed batteries do indeed bounce as they lose charge – but the highest bounce occurs when the battery is half full.
Using a combination of X-rays and lab experiments, engineers confirmed batteries bounce as they lose charge due to zinc oxidisation. But, the ‘maximum bounce’ occurs when the battery is around half full (shown) meaning the test doesn’t tell you if a battery is dead, it just tells you whether the battery is fresh
‘The bounce does not tell you whether the battery is dead or not, it just tells you whether the battery is fresh,’ said Daniel Steingart, an assistant professor of mechanical and aerospace engineering and the Andlinger Center for Energy and the Environment from Princeton University.
The battery bounce test became popular when Cincinnati-based electrical engineer Lee Hite posted a video demonstrating the theory.
In Mr Hite’s tests, he dropped ‘good’ and ‘bad’ batteries – charged and empty – through a tube to test their bounciness before opening them to discover how they differed inside.
He conclude that good batteries don’t bounce because of the anti-bounce theory.
This theory states the gel-like substance in a good battery creates a downward force, keeping it flush with the floor when dropped.
Professor Steingart, along with his colleague Shoham Bhadra, were inspired by this, and similar videos, to put these claims to the test.
The height of the bounce increases as the batteries discharge, and this has led to the common conclusion that internal changes related to the reduction in charge cause of the higher bounce.
But Professor Steingart was intrigued by this discharging, because it is not linear.
Instead, the height rapidly increases and then levels off – a discovery Professor Steingart and his team had made previously in their work into the internal changes related to battery discharge.
So they dropped batteries through plexiglass tubes, and used a computer microphone to record them striking a benchtop. The researchers were then able to use the time between bounces to determine the height of the bounce.