While lithium-ion batteries are extremely efficient, and not too hazardous to the environment, the simple fact is that they can become dangerously unstable if they happen to be over-discharged. And when I mean dangerously unstable, I mean that they can cause fires and destroy equipment.

There's no need to worry, though, as there are protective circuits inside lithium-ion batteries that shut down the battery if the charge ever falls this low.

However, while this protects your equipment, it also results in a very dead battery that responds to no form of treatment whatsoever if it happens to get seriously discharged.

But, how does such a 'fatal' discharge occur?
It happens when a lithium-ion battery is stored in a completely discharged state. You realize, of course, that this so-called completely discharged state is not actually fully discharged. But when the battery is left in storage, the charge continues to deplete slowly, until it ultimately falls below the safety threshold, and once that happens, the protective circuit kicks in and terminates the battery.

So, what do you do with a lithium-ion battery that has 'died' in this fashion?
You usually throw it away. However, it is not necessary to do so, as there are now ways to restore or recondition that battery and bring it back into working order.

One of the easiest ways to recondition lithium-ion batteries that have died due to their protective circuit activating is to buy one of the modern chargers that have an awakening feature.

These chargers have a 'boost' function that continuously puts a very minimal charge into the battery that slowly raises the charge in the cell. There is a good chance that if the charge in the cell can be raised above the level of the failsafe circuit, that the cell will then begin to charge normally, and return to full function.

However, there are certain safety criteria that have to be met while you are doing this.
If you put your lithium-ion battery into such a charger and apply the 'boost' function to the battery, you must wait no more than a minute before stopping the charging process. This is because a battery can get quite unstable when its residual charge is this low, and you really don't want accidents.

As a general rule, you should not attempt to recondition lithium-ion batteries that have remained in a dead state for more than a week.

This is because alterations may have occurred in the internal structure of the battery that would cause it to short-circuit when you plug it in, and this is something that you definitely do not want.

Another thing that you need to be very careful of when reconditioning a lithium-ion battery is that you do not reverse the polarity of the battery when putting it into the charger.

A good charger will refuse to function if the battery has been inserted in it with the poles reversed.
Please note that if you switch on a charger when the battery has been inserted in it with the poles reversed (and if the charger does not have its own protective circuits), it could result in your battery being permanently damaged.