Why Can Laptop Batteries Never Exceed 100 Wh?

Why Can Laptop Batteries Never Exceed 100 Wh? When confronted with a salesperson, you may be surprised to learn that the battery capacity is limited to 99.9 Wh for some laptops, most common for those in the 13-inch range.

Batteries are the power behind portable electronics like laptops and smartphones. The capacity of a battery is directly related to the amount of energy it can store. Although watt-hours, typically expressed as Wh, are not the be-all and end-all for a smartphone or laptop battery. Other vital factors, such as chemistry and voltage, factor into choosing the best battery for your device.

Wh (or mAh) is essential when considering which battery pack to buy. Sometimes, you may be offered an option to buy a laptop with a larger capacity battery, but only up to 99.9 Wh. Why? Read on to find out!

If you have considered buying a laptop, you may have noticed that the size of the batteries never exceeds 99.9 Wh. Do you want to know why? In this article, you know what a Wh is, the reason for a limit, and what other considerations you should consider regarding this matter.

What are Wh or watts per hour?

The abbreviation Wh refers to the unit of measure watts per hour. It should not be confused with the watt, which measures instantaneous electrical power consumption. Instead, the watt or watt-hour is used to calculate the electrical consumption during a specific period. 

For example, if we run an appliance that is 50 watts (or 50 W) for one hour, it will have consumed 50 watts per hour (or 50 Wh). Similarly, your consumption will be 100 watts per hour (or 100 Wh) in two hours.

Taking the above as a reference, you should know that the unit chosen to measure batteries’ capacity in laptops is the watts or Wh. A mid-range device usually has about 40 Wh, while a high-end device can reach 99.9 Wh. However, no matter how much money you decide to spend on your new laptop, you can never have a computer that exceeds this figure. Why?

A safety limit

laptop batteries never exceed

The batteries included in laptops (and any other electronic or mobile device) are delicate and unstable components that can ignite and cause a severe fire. In some cases, they have even exploded. This is not something that happens frequently, and, in most cases, a laptop will never suffer this type of breakdown. However, we cannot deny that batteries always involve certain risks, mainly when used intensively and near a heat source.

Due to this, the official organization applies restrictions to transport this type of battery. Anything that exceeds 99.9 Wh is considered dangerous goods and must be transported following a special protocol.

It is necessary to understand the seriousness of the matter. Think for a moment about the problems that fire inside the cabin of an airplane would cause. Some experienced pilots claim that this is far more dangerous than an engine stalling or bursting into flames. 

This statement may seem exaggerated, but aeronautical professionals, including pilots and crew, are prepared for these inconveniences. However, a fire inside the plane behaves unpredictably and could destroy essential parts of the plane before it is possible to land safely.

Authorities prohibit exceeding

Now that you know exactly what a watt-hour is and why you can’t find laptops with a battery greater than 99.9Wh, some sources are saying about it. Thanks to this, we will establish the limitations imposed by different factors related to the world of aeronautics. In addition, it will allow you to find out if there are any other limitations related to the 100-watt hour limit.

United States Federal Aviation Administration

laptop batteries

In the United States, the United States Federal Aviation Administration, or FAA, applies Wh limitations to the following products:

  • External batteries or power banks
  • Phone battery charging cases.
  • Rechargeable and non-rechargeable lithium batteries.
  • Phone or laptop batteries.
  • Portable chargers.

Regarding these components, it mentions that “ Lithium-ion (rechargeable) batteries are limited to a rating of 100 watt-hours (Wh) per unit ” as manufacturers are aware of these limits. 

The Consumer Product Safety Commission set specific limits for the amount of lithium-ion the average person can carry. This amount is sufficient for carrying the most common types of batteries in electronic devices, like phones and laptops. Or what is the same: there is no need to worry too much because most electronic products comply with this limit.

Passengers may carry up to two spare batteries of any size up to 101-160 watt-hours (Wh) or two lithium metal batteries of no more than two grams each, only on specific occasions and with the airline’s approval. This may be necessary to include professional audio or video equipment in your luggage.

European Union Aviation Safety Agency

Another regulatory body that we should consult to know all the details about the limit of 99.9 Wh is the Europen Union Aviation Safety Agency. According to the European Union Aviation Safety Agency, passengers are advised that all portable electronic devices (PEDs, such as cameras, laptops, and cell phones) should be carried in their hand baggage and not in checked baggage. On the other hand, remember that “ under normal circumstances we can use our laptops, e-readers, tablets or MP3 players on board to work, read, listen to music or watch movies ”.

The EASA (European Union Aviation Safety Agency) notes that the battery should not exceed 100 watt-hours or 2 grams of lithium content, both for rechargeable lithium-ion batteries and lithium metal batteries. The former limit is for rechargeable batteries, and the latter is for those not.

99.9 Wh does not mean limiting the autonomy

After the analysis, it is clear that manufacturers are not interested in launching devices with batteries that exceed 99.9 Wh. Otherwise, its transportation and distribution would be considerably complicated. 

In addition, the user would hardly be able to take his laptop with him on plane or rail trips. However, this does not mean that autonomy has been eliminated. It is necessary to remember that other factors, such as the battery’s capacity, are weighed when operating under autonomous conditions.

Without going any further, the very applications running on the laptop can positively or negatively influence autonomy. The operating system itself must also be well optimized to reduce power consumption. And the same can be said of the processor. The main manufacturers are working to make their CPUs more and more efficient. Finally, it can be positive to calibrate the battery of the equipment.

Conclusion

So, the battery of a laptop can never exceed 100 Wh. An international standard imposes a limit, so it cannot be changed. 

The only way to find larger batteries would be to create a laptop much more extensive and heavier than usual. That doesn’t sound very appealing. Imagine carrying a 20 kg laptop around! Here is an example of technological innovation meeting a seemingly irrational limitation. 

While this is unfortunate for us eager consumers, it does ensure that we can take advantage of the extra space left in the battery to put in more powerful hardware. And the good news is that laptops will continue getting smaller and more powerful in the coming years!

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