Batteries bounce when dead

Is your car battery dead?

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How to Test if 1.5v Batteries are Still Good

Testing batteries ensures they are charged and ready for use. Operating a device without knowing the batteries are charged means they may not function as expected, causing your device to fail to operate. Several simple methods are available to quickly test and determine if a battery is charged and functional.

Testing batteries ensures they are charged and ready for use. credit: Daniil Dubov/iStock/GettyImages

Use a Multimeter

The most effective means of testing a battery is with a multimeter. You can test AA batteries and other battery types and styles with the device. The meter shows the voltage output, which indicates whether the battery is weak, dead or functioning normally. Not everyone has a multimeter handy, and other methods of testing are available for AA and AAA alkaline batteries.

The familiar AA and AAA battery types are 1.5 volts, and the rechargeable versions are 1.25 volts. You might wonder at what voltage is a 1.5 V battery dead. If the battery tests at less than 1.3 volts in the multimeter, it no longer functions properly and should be replaced.

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To run the test, set the multimeter to the DCV setting and set the voltage to 20 so it can read above the battery voltage. This simply places the reading capabilities in a safe range. Touch the black clip to the positive side and the red clip to the negative side of the battery to read the voltage. A reading of 1.3 to 1.5 volts means the battery is good.

A brand new battery might show a higher voltage level. Reading at 1.6 or slightly higher is not uncommon, and this is the reason for setting the DCV to a level of 20 volts as the maximum threshold.

The Drop Test

A voltmeter or multimeter is overkill for testing a few household batteries. If one is readily available, it makes sense to use it, but otherwise, a simple drop test can reveal the condition of alkaline batteries. The chemical composition in alkaline batteries shifts when the battery is dead, and the way a battery reacts when it is dropped reveals the charge status.

Hold the battery vertically, a few inches above a hard surface and drop the battery. A good battery lands with a solid sound and stands upright. A bad battery bounces and topples over. This test is simple and quickly determines which batteries are worth keeping.

Keep in mind that this test only works for alkaline batteries. Lithium battery types require a voltmeter or a device test to determine whether they are functional. The chemical composition does not change in lithium batteries, and the bounce test is irrelevant. However, alkaline batteries are far more common in the household.

Test in a Device

The device test is worth pursuing because the batteries must function well enough to power the device. This does not, however, reveal the charge for each individual battery because some devices can power with one weak battery and a few fully charged batteries.

Load up the device with batteries and test for power. If the device operates normally, run it until the batteries require replacement. Otherwise, replace them immediately. If the device continues to fail, the batteries may not be the problem. Test them in a different device to determine if the device has issues beyond the batteries. In some cases, cleaning the contacts resolves the issue.

While the device test is not foolproof, it is easy and convenient for any type of battery. The drop test for alkaline batteries is a better route for testing individual batteries, however.

Battery bounce test often bounces off target

Don’t throw away those bouncing batteries.
Researchers at Princeton University have found that the common test of bouncing a household battery to learn if it is dead or not is not actually an effective way to check a battery’s charge.

“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.

Shoham Bhadra, a doctoral student in electrical engineering and the Andlinger Center for Energy and the Environment (left), and Daniel Steingart, an assistant professor of mechanical and aerospace engineering and the Andlinger Center, found that changes in the bounce of common batteries signal important changes that occur as the battery discharges.

Photo by Frank Wojciechowski

The battery bounce test, popularized in online videos, shows that fully charged batteries bounce very little when dropped, while those that have been used for a while bounce higher. The height of the bounce increases as the batteries discharge, and that has led to the common conclusion that internal changes related to the reduction in charge are the cause of the higher bounce.

“A year ago a buddy of mine who knows I work on this sent me this video and said did you know this happens?” Steingart said. “I didn’t. But I had a bunch of batteries on my desk and I was able to verify it.”

Steingart was intrigued by how the bouncing changed as batteries discharged — it was not a linear increase. Instead, the height rapidly increased and then leveled off. His research team has been working for some time on internal changes related to battery discharge, and he wondered whether the changing bounces reflected an important change in the batteries.

They devised a quick experiment in which they dropped a common battery through a plexiglass tube and used a computer microphone to record it striking a benchtop. The researchers were then able to use the time between bounces to determine the height of the bounce.

“What I really loved about this experiment is that the result holds a lot of scientific importance, but it is also the kind of thing I can show to someone without a scientific background and they can still get something out of it,” said Shoham Bhadra, a graduate student in electrical engineering and the Andlinger Center for Energy and the Environment and the lead author of the research paper reporting the findings.

In other research into the materials used in alkaline batteries, the team had obtained data from X-ray scans of batteries made at Brookhaven National Laboratory. They combined the results of their drop tests with the scan data to evaluate what caused the changes in bouncing.

The battery bounce test, popularized in online videos, has led to the common conclusion that a high bounce means a dead battery. But researchers at Princeton University have found that bouncing is not actually an effective way to check a battery’s charge. Video courtesy of Shoham Bhadra, electrical engineering and the Andlinger Center for Energy and the Environment, and Daniel Steingart, mechanical and aerospace engineering and the Andlinger Center

They found out it had to do with the way the batteries produce power. Electricity is generated by a chemical reaction inside the batteries as zinc changes to zinc oxide. Initially, a layer of zinc surrounds a brass core in the battery like a donut around a hole. As the battery discharges, the zinc donut gradually changes to zinc oxide.

“The zinc oxide begins to form on the outside and it pushes its way to the core,” Steingart said. “As you get more and more zinc oxide, and the zinc oxide begins to appear everywhere in the zinc layer, the battery gets bouncier and bouncier.”

In an article published March 13 in the online version of The Journal of Materials Chemistry A, the researchers conclude that the bounces increase because the zinc oxide forms tiny bridges within the zinc material, which decreases the mechanical damping of the battery.

“The zinc starts out as a packed bed of particles that all move very nicely past each other,” Steingart said. “When you oxidize the zinc, it makes bridges between the particles and makes it more like a network of springs. That is what gives the battery its bounce. ”

Steingart said that is not too surprising, as zinc oxide is listed as a component to add bounce to golf balls in many patents.

But the formation of the bridges reaches a maximum “bounce level” well before the oxidation of the zinc is complete. That means that the bounce will reach a peak and level off well before the battery is dead.

“While this test seems a parlor trick, the way in which the coefficient of restitution changes provides startling insight to not only what reaction is occurring into the battery, but where the reaction is occurring as a function of state of charge,” Steingart said.

In addition to Steingart and Bhadra, the researchers on the project include Benjamin Hertzberg and Andrew Hsieh, postdoctoral researchers in mechanical and aerospace engineering at Princeton and at the Andlinger Center for Energy and the Environment; Mark Croft of Rutgers University; Joshua Gallaway of City University of New York; Barry Van Tassell of City College of New York; Mylad Chamoun, Can Erdonmez and Zhong Zhong of Brookhaven National Laboratory; and Tal Sholklapper of Voltaiq.

Support for the project was provided in part by the National Science Foundation, the U.S. Department of Energy and Brookhaven National Laboratory.

Do dead batteries really bounce?

You’ve probably heard of the bounce test for dead batteries- simply drop a battery, and if it bounces, it’s dead. It turns out that this isn’t completely true. Conventional batteries have an outer layer made of zinc, which once hooked into a circuit, is slowly converted to zinc oxide, while releasing electrons and allowing them to flow, thereby creating electricity. Before a battery has been hooked into a circuit, the zinc molecules aren’t aligned in any particular way. This means that when dropped, these molecules can move slightly, and absorb the kinetic energy. However, once a circuit is made with the battery, the molecules are aligned, and the kinetic energy from a dropped battery can’t simply go into the molecules, but instead transfers into the bonds between molecules, causing a recoil, or bounce action. So while it’s true that dead batteries bounce, so do half full batteries, and even 99% full batteries. All this test can really tell you is whether a battery is brand new or not.

@AdaMcVean

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Even though most camera bodies these days use some sort of Lithium-ion battery, chances are there’s still some gear in your bag that still runs off alkaline batteries. If you’ve ever found yourself in need of checking the charge on those batteries but you happen to leave your volt meter at home (I know … what were you thinking!?) here’s a cool little life hack that’ll give you the info your need.

The test comes to us courtesy of life hacker and how-to guy Kipkay. All you need to perform the test and check if your alkaline batteries are juiced is a hard surface.

Drop each battery (with the flat, negative end down) from a couple of inches up. If the battery is charged, it should make a solid thud and most likely stay standing. If, however, the battery is dead, it will bounce and fall over immediately.

Unfortunately, this will only work with alkaline batteries, so don’t go dropping your Lithium-ion rechargeables. The reason this works is that, as alkaline batteries discharge, the chemistry inside changes and produces Hydrogen gas, creating pressure and making it easier for the battery to bounce and topple.

Chances are you’re already familiar with this “out-gassing” as it’s called. It’s the same force that often causes the insulating seals and/or battery canister to crack open and leak.

For more neat life hacks, be sure to pay Kipkay’s website and/or YouTube channel a visit.

(via Gizmodo)

Update: Here’s a second video by bajarider1000 demonstrating the exact same trick:

Update: It appears that the drop test differences seen in the videos above may have more to do with the brand of battery than the batteries’ level of charge. Consider this test “probably bogus.”