4 Signs Your Rechargeable Batteries Are No Longer Safe to Use

There is a limit to the number of times you can use rechargeable batteries before they stop working completely. After completing a certain number of charge cycles, a battery will reach a “failure point” where its health and capacity per cycle will begin to degrade much more quickly. However, just because your battery’s charging capacity is degrading doesn’t mean it’s unsafe to use, right? Well, that may be true from time to time, but there are a few tell-tale signs that your rechargeable batteries are no longer safe to use.

Faulty batteries often show signs like overheating and may not be able to power your device optimally. In extreme cases, the battery may even show physical damage or begin to emit chemical odors. A defective battery can ultimately pose a risk of damaging the device or even harming the user. There are times when it may be best to err on the side of caution by recycling that old battery early and inserting a new cell instead. But if you stay alert for these four danger signs, you can avoid disaster from faulty rechargeable batteries.

Lithium-ion batteries can heat up due to the chemical reaction that occurs when the battery charges or discharges energy. Certain actions, such as running intensive apps on a smartphone or using a device’s “quick charge” feature, can cause the battery to heat up even more. But if the device becomes abnormally hot to the point that the battery itself is too hot to touch, you could find yourself in a dangerous situation. Also pay attention to the shape of your device, as any swelling or bulges may indicate that heat has caused gas buildup. It could even indicate that your lithium-ion battery could catch fire.

This is also why lithium-ion batteries should not be thrown into a regular trash or recycling bin, especially if the battery itself is damaged or defective. Even small lithium-ion batteries have some risk of thermal runaway. Unlike traditional fires, a thermal runaway is a self-sustaining chemical fire that can escalate quickly.

Pay attention to cracks or bulges in the battery case. These are types of physical damage that you should never ignore, even if the battery still appears to be working fine. Pay close attention to battery corrosion caused by heat, pressure, or chemical reactions. If you notice a clear or white deposit on or around the battery, it probably means corrosive electrolytes are leaking. These chemicals can eat away at the metal or electrical components of a device. Worse yet, they can cause skin irritation or even vision loss if the chemicals come into contact with your eyes.

It’s not a bad idea to regularly check your battery for damage, especially if it’s getting old or if you keep a protective case on your device. If you notice a swollen battery, do not try to puncture it, as this could trigger thermal runaway. Instead, carefully dispose of your old battery and replace it with a new one immediately.

A healthy lithium-ion battery should not give off any particular odor. On the contrary, it might smell plastic or “clean” if you inspect it closely. But if you detect a sweet, pungent fruity smell coming from an electronic device, it may be coming from a rechargeable battery that is no longer safe to use. This is the chemical smell of electrolytes leaking from the battery case. It is often compared to the solvent scent of acetone found in nail polish remover.

Other odors to consider include smoky or burning smells which could indicate internal components are affected by heat damage. In fact, heat damage is more likely if there is a leak in the battery, as this means the chemical stability has been compromised and flammable gases could also escape. If you notice the smell of overheating electronics accompanied by a battery acid smell similar to acetone, stop using the device immediately.

If your battery-powered device has a flickering light, a shaking motor, or any function that isn’t working as smoothly as it should, it could be a battery problem. A faulty battery can produce inconsistent voltage, which is dangerous because voltage fluctuations can damage the device or cause dangerous overheating. This could also be a sign that the battery is degrading, which of course can lead to chemical leaks.

As a general rule, there are certain devices that you should never insert rechargeable batteries into. These include devices that you rarely use or those that you only use for very short periods of time, such as a TV remote control. This is because rechargeable batteries are constantly discharging power even when not in use and can eventually reach a “deep discharge” state that will make it difficult for the battery to properly power a device. In the worst case scenario, the constant discharge of energy can eventually cause corrosive chemicals to leak from the battery.