What Happens When A Laptop Battery Runs Out?

You may have heard conflicting suggestions about what happens if you let the laptop battery run out. Some may say it’s advisable and you should do it once in a while, while others maintain that it can be harmful and make the battery deteriorate with time. So, what really happens when your laptop battery runs out?

When a laptop battery runs out, it goes into a deep discharge state, where chemical reactions change, reducing its longevity. You should not let lithium-ion batteries discharge completely. However, older laptop batteries need to drain fully to last longer because of the memory effect.

If you want to know more, read the rest of this article. I will explain what happens when you let the laptop battery drain and how it can affect the battery and your laptop.

Moreover, I will cover some other important aspects of this topic, such as how a laptop battery works, signs that tell you the battery is dying, and how to ensure it lasts longer.

A laptop charger is being plugged into a fully drained laptop.

How Letting Your Battery Drain Completely Affects Your Laptop and Its Battery

Whenever you get a new laptop, you get all sorts of advice about keeping the battery healthy for as long as possible.

However, this advice is often contradictory, especially when it comes to letting your laptop battery drain completely.

Letting the battery run out completely will affect your laptop and its battery adversely in most cases.

You may not notice a difference if you let the battery run out once or twice, but if you do it constantly, you’ll see that it will become much weaker as time passes and might soon need to be replaced.

What Is the Deep Discharge State?

When you let the battery go to 0%, your laptop will shut down, and the battery will go into a deep discharge state.

In this state, the battery cell voltage drops below the recommended limit, which can be fatal to the battery, not to mention a safety risk.

While in the deep discharge state, specific chemical reactions happen inside the battery, damaging it considerably. You may be able to recover from this state, but your laptop battery won’t be the same. 

Moreover, these chemical reactions may cause the battery to swell noticeably. A swollen battery is a fire and explosion hazard, and it means you should immediately stop using your laptop and disconnect it from power.

So how come some people still recommend letting the battery drain when it’s obviously harmful and even dangerous?

While this is true for most laptop batteries nowadays, it was the opposite for earlier laptops. See the types of laptop batteries below to learn more.

Types of Laptop Batteries and How Draining Affects Them

The main reason why you get contradicting points of view about draining your laptop battery is that some earlier laptop batteries actually benefit from total discharging.

There are various types of laptop batteries out there, with different needs. 

Some of the advice you hear refers to older types of batteries that are very rare nowadays. The components of laptop batteries have evolved with time, and so have their needs. 

However, some people might not realize that what used to apply to previous generations of laptop batteries does not apply to the new ones. Consequently, you may get inaccurate information about the battery life of your laptop.

To make sure you’re taking care of your laptop battery the right way, you need to know what kind of battery you have and how to care for it specifically.

Let’s see the different types of batteries and what you need to do to keep each of them healthy.

Nickel-Cadmium (NiCad) Batteries

An older laptop battery.

The earlier types of laptops used nickel-cadmium batteries, which are no longer used because cadmium is highly toxic.

These batteries were affected by the way the laptop was charged, thanks to the memory effect. The memory effect caused the battery to deteriorate much faster if it was not fully discharged before being plugged into a charger.

Nickel-cadmium batteries require you to let the battery drain completely before recharging it before using your laptop; otherwise, the battery will be damaged.

For instance, if you let the battery go to 30% and then plug it in, you would cause the battery to “memorize” the shorter operating cycle, causing it to last significantly less next time.

As I mentioned above, cadmium is very toxic and harmful to your health, which has led to it being banned in battery manufacturing.

As a result, very few, if any, laptops nowadays have this type of battery, so you won’t have to worry about this battery and its effects.

Nickel-Metal-Hydride (NiMH) Batteries

As a result of the Cadmium ban, laptop battery manufacturers came up with another type, nickel-metal-hydride (NiMH) batteries.

Even though they were made of different materials compared to the Nickel Cadmium ones, these batteries were still subject to the memory effect.

NiMH batteries feature several improvements compared to their predecessors, but unfortunately, they had issues regarding their longevity.

Although these batteries were not as affected by the memory issue, they still required a full discharge and recharge.

These batteries are still used in different applications but are not commonly used for laptops anymore. The short lifespan makes them unsuitable for laptop use, which is why manufacturers have developed a better alternative.

Lithium-Ion Batteries

A modern laptop battery is being held at its ends.

The most commonly used laptop batteries nowadays are lithium-ion batteries. These batteries outperform NiMH batteries in several areas, including longevity.

They are more powerful and more environmentally friendly than both of their predecessors.

Most importantly, as far as laptop batteries are concerned, lithium-ion batteries are not subject to the memory effect.

They don’t need to be fully drained to last longer. In reality, the opposite is true. Fully draining them can be detrimental to the battery life, as I explained at the beginning.

Most laptops nowadays use lithium-ion batteries, so you should not consider the memory effect for your laptop.

It’s recommended to keep these batteries at a charging level of between 20 and 80 percent and not let them drain under any circumstances. 

If anyone advises you differently, know they’re probably talking about the previous two types of batteries, even though they might not know.

How To Tell if Your Laptop Battery Is Dying

Like everything else, laptop batteries deteriorate with time, making them inefficient and unable to maintain the laptop working for a long enough time.

When a laptop battery dies, you may need to replace it or replace the whole laptop. But are there any signs that would tell you that the laptop battery is on its way out before it dies on you suddenly?

Fortunately, the laptop battery gives several different signs that can help you realize that something is wrong and that you need to think of a replacement:

  • The battery doesn’t last long. Even after fully charging it, the battery lasts only a couple hours or even less before needing recharging. A good laptop battery should exceed 6 hours of use.
  • Takes a long time to recharge. If it takes your laptop several hours to fully charge, the battery might be on its way out, and you need to replace it. It should only take 3 to 4 hours tops to charge fully from around 15%.
  • The battery never gets fully charged, even after several hours. If you have a Windows laptop, you may click on the battery icon on the lower right part of the screen. If it says “Plugged in, Not charging”, even after a long time, it means that the battery should be replaced.
  • The laptop turns off by itself out of nowhere. Your laptop powering off while you’re using it is a sign of trouble. There’s no reason for your computer to turn off without warning unless the battery is almost dead. Replace the battery as soon as you can. 

What To Do if the Laptop Battery Is Dead

If you don’t know what signs to look for or cannot notice, the laptop battery may die seemingly out of nowhere, leaving you to scramble for a solution. What can you do in this case?

Naturally, one solution would be to replace the battery, but that’s not always an option. You have a few ways of reviving the battery for some time.

However, these temporary solutions don’t guarantee much more time; you can have enough time to finish your work and back up important data.

Reviving NiCad or NiMH Batteries

If you have an old laptop with a NiCad or NiMH battery, you can try to chill it by simply putting it in the freezer. Yes, as weird as it sounds, freezing might work with the memory effect batteries. 

To try this method, follow these steps:

  1. Remove the battery from the laptop; if it’s not removable, don’t try putting the whole laptop in the freezer.
  2. Wrap the battery tightly with a dry and clean cloth.
  3. Put the wrapped battery in a Ziploc bag
  4. Place the battery in the freezer.
  5. Leave it for around 12 hours.
  6. After 12 hours, remove the battery from the freezer and let it come to room temperature.
  7. Re-insert the battery into your laptop.
  8. Turn on the laptop and see if it works.

Remember, this method only applies to earlier laptop batteries; don’t try this with lithium-ion batteries because you might destroy them completely.

Reviving Lithium-Ion Batteries

The Lithium element is listed on the periodic chart.

If you have lithium-ion batteries, your battery is not as likely to die on you suddenly, but if it’s an old battery, it can stop working at some point.

You can try reviving it by cooling it off; turn the laptop off immediately and move it away from a hot environment. A cooling pad can help your laptop battery avoid too high temperatures.

You could also revive the battery using a charger that has the revive function. These chargers can be found online or in electronics stores and can recharge the battery even if it’s in deep discharge mode.

Another way is to remove the battery and use an external source to revive it.

For this method, you need to have a basic knowledge of electronics and certain tools that can help you, like crocodile clips and a multimeter.

Important: Do not attempt this method unless you know what you’re doing.

Should I Keep My Laptop Constantly Plugged Into an Outlet?

A charger is plugged into the back of a laptop.

You may have heard that leaving the laptop plugged into the charger all the time is a good idea, given that you’ll never risk running out of battery power at the worst possible moment.

Your laptop running on AC might also be better for battery health, right?

Unfortunately, there’s no satisfying answer to the “battery or AC” question.

Different laptop manufacturers give various suggestions, and the results in practice are not conclusive one way or the other in the short term.

However, keeping your laptop constantly plugged into a charger will indeed cause the battery to heat up more and, as a result, deteriorate more quickly. In the long term, running the laptop on AC may do more harm than good.

On the other hand, continuously letting the battery almost run out is also harmful. As I explained above, the battery may get damaged when you’re not using the charger and you let the battery drain completely.

Only using your laptop when unplugged can shorten the battery’s lifespan.

Laptop manufacturers are divided on this topic. Some companies recommend using the laptop while plugged in, and some say there’s no difference.

Others recommend doing a combination of the two, only letting the battery drain up to a certain point once in a while. You can try whichever method you like and see how your laptop’s battery reacts.


Letting the battery of your laptop drain entirely is not a good idea for most laptop batteries nowadays.

Lithium-ion batteries don’t last long if you let them drain and recharge completely, so you need to make sure to keep the battery between 20 and 80 percent.

Older laptops with NiMH or NiCad batteries do need to drain completely to last longer because of the memory effect.

If these laptop batteries die, you can try detaching them and freezing them. If your lithium-ion battery dies, try cooling it, using a revive charger, or charging with an external source.