Spinning a cell phone battery means it's overcharged

My mom was told today that if a cell phone battery spins, it means it is over-charged and because it is over-charged, it has expanded causing the phone to use more battery power causing the battery to drain faster. But this only applies to new batteries–not older ones.

I could not find any evidence of this when I tried googling it. Anyone know?

Spins? Like, you take the battery out and set it on the table and flick it and see if it spins? Or…something else?

Yeah, like spin the bottle. She removed it from the phone, set on the counter, and gave it a spin.

I think there’s been a miscommunication. If you can spin an egg, it’s been boiled (or is possibly rotten). A fresh uncooked egg will quickly wobble to a stop.

I’ve been dealing with two-way radios and cell phones for almost 20 years. There is nothing in a battery that will change so much that you could detect the change by spinning it.

And there is no such thing as an overcharged live battery. There’s a battery that needs to be charged, a battery that is fully charged, and a battery with burned out cells (i.e. dead) from keeping it on the charger for too long (say two weeks or so…).

So a good way to find out if a battery has been “overcharged” is to see if it’s still working. If it’s dead, it’s been “overcharged.”

The egg test is thus: You spin an egg on a tabletop. Then you quickly stop it with the palm of your hand, then lift your hand. If the egg starts to spin again, then its liquid insides are still in motion, and it’s thus a raw egg. But if it stays stopped, then it’s a hard-boiled egg.

No no, you break the egg open. If it’s all liquid and gooey inside then it’s raw. If it’s solid white with a yellow center, it’s been boiled.


That makes sense, but from experience I can tell you that the above-described way works fine. Uncooked eggs just won’t spin very well.


I think I know what’s going on. I have several battery packs that have bowed at the sides due to heat during charging. Rapid chargers cause the batteries to get pretty warm…hot even.

That said, I’ve never known lithium-ion batteries, used in cell phones, to get nearly as hot as the Saber batteries during rapid charge. Further, most cellular batteries are already somewhat contoured and may spin anyway.

I have to disagree with this. Particularly with the older rechargeable chemistries, like NiCd and NiMH, it is possible to overcharge them. In this sense, it means that the battery is fully charged–that is the chemistry that drives it has been fully reversed–but the charger continues to push the charging current through it. At this point, the current finds other work to do, such as heating the battery even more or electrolyzing the water. This begins to break down the electrolyte, in particular by drying it out. Now, the battery may still “work”, but you’ll almost certainly start noticing a decrease in use time especially after this has happened a few times.

NiCds are more susceptible to this kind of thing, and so-called rapid chargers were the biggest culprits back when the NiCd chemistry was popular. You could get 5-7 years out of a set if you were very rigorous with proper care and feeding of your NiCds, but most people didn’t charge and discharge them properly and the typical lifespan was about 2-3 years. The chargers are smarter now, incorporating ciruitry to detect the battery’s state of charge, and the chemistries are more forgiving of slight abuse, so I think that’s helped things.

A little clarification here:

Quickly charging a nickel-based battery is actually good for it during the first half of the charging cycle. A good charger will automatically cut back on current during the second half. And that’s the problem… a lot of cheap “rapid chargers” do not do an adequate job of cutting back on the current during the second half of the charging cycle.

Yes, all well and good - but I’ve heard you can get a cell phone battery to stand on its edge on the first day of Spring (the Vernal Equinox). :smiley:
Any truth to this?

Normally cell phone batteries are flat rectagular prisms, right? I bet jnglmassiv is right and whoever told the OP’s mom that an overcharged battery spins is referring to the bulging out of the sides of the battery after it has overheated. Two of my (pretty modern chemistry – lithium ion) cell phone batteries have bulged out after about 1.5 years of use.

I don’t know, but I’ve heard that fresh cell phone batteries will sink if placed in a pot of water, and overcharged ones will float.

I believe this is only true if the battery is installed in the phone at the time.