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Can Lithium-Ion Batteries Be Overcharged?
You may have seen reviews of lithium-ion batteries stating that the batteries cannot be overcharged. That makes the battery safer, according to the reviewer. On the other hand, there have been plenty of stories detailing how fires were started by overcharged lithium-ion batteries. So which is it? Can they be overcharged or not?
Salt Lake City’s Pale Blue Earth, makers of high-tech USB rechargeable batteries, says the answer to the question is both ‘yes’ and ‘no’. Whether or not lithium-ion batteries can be overcharged depends on their design and construction. When designed properly, the chances of overcharging are slim to none. When designed improperly, all bets are off.
High Density and Flammable
Lithium-ion batteries are preferred over NiCad and NiMH rechargeables because of their exceptionally high power density. Lithium-ion’s higher density allows batteries to store more energy without having to increase their size. That is why a typical rechargeable li-ion battery lasts longer than a NiCad or NiMH unit.
Unfortunately, lithium-ion batteries are also highly flammable. This is where structure fires come into play. Take the case of a recent house fire outside of Knoxville, Tennessee. It did pretty significant damage to the home’s garage. Fire investigators determined the incident was caused by overcharged lithium-ion batteries in the garage. The batteries overheated and burst into flames, followed by the flames spreading throughout the space.
Lithium-ion batteries are so flammable that the Post Office and most delivery companies are very strict about shipping them. When they are shipped via air or rail, they have to be packed in a certain way so as to prevent them from overheating. Any lithium-ion battery that overheats could potentially combust.
Overcharging a lithium-ion battery could cause it to overheat. So how do companies like Pale Blue Earth prevent it? By building protective circuits into their products. A protective circuit monitors the battery’s charge and, when full, cuts off the incoming current.
Protective circuits in Pale Blue Earth batteries are built into the actual casing. As such, you can see them. But the protective circuits in your laptop are different. They are generally not built into the batteries themselves. Rather, they are mounted in the laptop case.
Where protective circuits are located varies from one battery design to the next. The one thing they all have in common is that they prevent overcharging, overheating, and fires – which leads to yet another question: what about lithium-ion batteries that do start burning?
Absent or Damaged Circuits
When batteries equipped with protective circuits still overheat and burn, the likely cause is defective circuitry. Either the circuitry was defective from the start or it was somehow damaged after the fact. It either doesn’t properly measure the battery’s charge or it is unable to cut off current when charging is complete.
Unfortunately, it is not unheard of for battery manufacturers to not including protective circuits. These types of batteries are generally cheap batteries made in some countries where regulations are not as stringent.
Also, consider the fact that lithium-ion batteries can combust even when not overcharged. Simply exposing them to high temperatures can do the trick. That is why so many car fires related to e-cigarettes were reported in the early days of the e-cig revolution. People were leaving their e-cig batteries in hot cars for hours on end.
So now you know. It is possible for lithium-ion batteries to be overcharged. And when it happens, they are at greater risk of overheating and combusting. Your best bet for avoiding the risks is to only purchase your lithium-ion batteries from reputable manufacturers. And if they ever show signs of defect, stop using them right away.