Nothing is more annoying than not having a charger handy or a way to plug in your laptop to recharge its battery! Well, guess what? You no longer have to worry about such an incident happening: the external battery will revolutionize your daily life!
Contrary to popular belief, an external battery isn't just for charging your mobile phone, tablet, etc., but also your laptop. So it's time to get one! The question remains: how do you choose the best one for your laptop?
Please note that for a PC external battery model to be suitable for your laptop, it must meet a series of rules:
- A compatible connector
- The same operating voltage (V)
- The power supplied must be equal to or greater than (W)
Through this guide, you will learn how to identify the external battery that best suits your laptop.
The features of your laptop charger
In order to find the perfect external battery for your laptop, you must first know its specifications.
Let's take the specifications of this portable charger as an example:
The output contains:
- Voltage: 19 V
- Current: 4.74A
- Power: 19 V x 4.74 A = 90 W
This means that this charger operates at a voltage of 19 V (volts) and provides a maximum current of 4.74 A (amperes), as well as a maximum power of 90 W.
By checking your laptop's specifications, you can avoid damaging it. Connecting it to a charger (or external battery) with a higher voltage could cause collateral damage .
The prerequisites for adapting an external battery to your PC
To replace your charger with an external battery, you should consider the following characteristics:
Charging port:
There are three different ways to power your laptop via an external battery, depending on the output port:
External battery with DC port:
When using this type of battery, please check that the external battery connector is compatible with a port on your laptop. Generally, a set of adapters is included with this type of external battery.
However, finding a suitable model for your laptop can be quite difficult. Not to mention that these batteries are bulky and require a wall outlet to recharge.
External battery with AC port:
With external batteries that include a 220V AC port, you can say goodbye to compatibility issues! You can directly connect your laptop charger to them. Simple enough, isn't it?
However, this battery is not perfect either. It has some drawbacks such as its large size, the need for an additional AC charger, and worst of all, some of the external battery's energy is lost when using the device's charger as an "intermediary".
External battery with USB-C PD port:
USB Type-C represents the future of connectivity! You can charge any device using a universal USB-C charger, without having to search for compatible connectors.
Equipped with the brand new PD (Power Delivery) technology, it also allows for powering high-power devices (Fast Charge).
If you have a latest-generation laptop, an external battery with PD is exactly what you need!
Otherwise, you will need to use a special adapter or cable with a USB-C connector (External Battery) on one end and a DC INPUT connector (Laptop) on the other.
This is why you need to be extremely careful when buying the cable, so as not to damage your PC.
Let's say we have a 20V charging laptop; it will only start charging after being connected to a 20V PD cable.
If the cable is less than 20V, the computer will not charge, and if it exceeds 20V, the computer will be irreversibly damaged.
Output voltage (V)
If you have an external battery with a DC or USB-C PD output, be sure to check that its output port has the same voltage as your laptop charger to avoid any problems.
The output voltage is usually indicated in the specifications of the external battery as "DC Output" or "USB-C Output".
What happens if my laptop is charging at a voltage of 19.5V*?
In reality, all electronic devices must withstand a voltage within +/- 10% of their nominal voltage. This means that if your laptop charges at 19.5V, it can handle a maximum voltage of 21.45V (19.5V + 1.95V), and therefore, a 20V external battery could be connected to it.
In addition to this, one must take into account the voltage drop that occurs in the cable connecting the external battery to the laptop, which varies between 0.15 V and 0.2 V for each meter of length (depending on the resistance of the cable itself).
Assuming the output voltage of the external battery is 20V, then the laptop would get a voltage of 19.8V (20V-0.2V).
There are also models with one or more DC output ports with a fixed voltage or a single multi-voltage DC port, the voltage of which can be selected to match the charging voltage of our laptop (by pressing the "power" button).
On the other hand, if you are using an external battery with an AC output, it is not necessary to check the voltage, since the charger used will be that of your laptop, which automatically transforms the 220V voltage into the computer's charging voltage.
Power supplied (W):
The final criterion to consider is the maximum power that the external battery's output port is capable of delivering:
We know that a computer needs maximum power when starting up. That said, it is recommended to use an external battery that can provide the same power as the charger or more.
But this time, in the following section, we will look at some situations in which it is possible to use a lower power model:
Guide to choosing your external battery:
First, we will see what needs to be checked depending on the type of external battery chosen to recharge our laptop:
Battery Type
External battery with DC port
- Check the voltage (V) and power (W) of the computer charger.
- Find an external battery with a DC output port, having the same voltage (V) and equal or greater power (W). You may encounter some problems:
- You may not find a model with the same voltage.
- You may also not be able to find a model with the same power, or may not want to spend a lot of money.
- Check that the external battery has a cable and/or connector compatible with the computer's charging port.
External battery with AC port
- Check the power supply (W) of the computer charger.
- Use an AC power bank with a power rating equal to or greater than that of the charger. Even then, you might not find a model with the same power rating, or you might not want to waste your money.
External battery with USB-C PD port
- Check the voltage (V) and power (W) of the computer charger.
- Find an external battery with a USB Type-C output port, a Power Delivery (PD) of the same voltage (V), and an equal or greater power output (W). Possible problems:
- Could not find a model with the same voltage.
- Not being able to find a model with the same power, or not wanting to waste your money.
What power output is needed from an external battery to charge a laptop?
Depending on the laptop model, your charger will be designed to provide a maximum power of 45W, 65W, 90W, 130W…
However, you may not be able to find a power bank with the same or greater power output as your charger, or you may simply want to save some money. In this case, you can buy a less powerful power bank, but under certain conditions:
Battery removal
Removing the laptop battery:
When the laptop battery is removed, the power required by the external battery becomes less than that supplied by its charger, since the energy needed to recharge its battery is no longer required.
Keep in mind that the power required to start a computer is always greater than the average working power, due to the current peak produced.
A trick to avoid the power surge at startup is to activate sleep mode as soon as your computer indicates a low battery. Then, connect and remove the external battery from your laptop. If you then deactivate sleep mode, you'll be able to use the external battery's power without experiencing that power spike at startup.
If you follow these usage guidelines, you can use an external battery with a lower power output than your charger, provided it delivers at least 70% of the charger's power. In other words, if your charger is 65W, the external battery must have a power output of at least 45W.
Recharging PC when off
Charging the battery with the laptop turned off:
An alternative would be to keep the laptop powered off by charging it.
This means that you will only need the power necessary to recharge the laptop battery, this power being the same as in the previous condition (45W) (at least 70% of the power of your laptop charger).
Recharge while the power is on
Charging the laptop and using it at the same time:
If you are not satisfied with the previously mentioned options, you can also use a lower capacity external battery before the computer battery is completely discharged (generally less charging power is required from 50% battery).
Therefore, when you connect the external battery while the computer battery is still not depleted, you avoid excessive power at the initial peak.
You absolutely need to know the starting peak of your laptop, as well as the power it needs to recharge its battery (while it is still half charged).
After reading these 3 tabs, we recommend, if possible, that you use an external battery with the same or higher power output as your laptop charger, while respecting the conditions of use.
How many hours can I use a laptop with an external battery?
Are you already thinking about buying an external battery for your laptop? Well, before anything else, ask yourself the following questions:
- What tasks do you typically use your laptop for with an external battery? Surfing the internet, office work, playing games, watching Netflix…? You will need to determine your computer's average power consumption.
- For the type of task chosen, how many hours does your laptop last with a 100% charged battery?
- What type of external PC battery will you use? With a DC, AC, or USB-C power supply port?
Calculating the average power consumption of a laptop
Don't panic! You don't necessarily need advanced knowledge or specialized equipment to know how much power your PC consumes when you use it daily; you can find out by taking a closer look:
- The energy stored in your laptop's battery.
- The estimated duration of tasks you typically perform with your laptop.
The battery specifications will indicate the energy stored in the laptop battery, measured in watt-hours (Wh). Alternatively, you can calculate it by multiplying the voltage (V) by the battery capacity (mAh) (image on the left: 15V x 2950mAh): 44Wh
Remember that a laptop battery degrades with use: its capacity gradually decreases over time. That said, it's highly likely that the battery's stored energy is less than its specifications indicate, especially if your computer is several years old and you've never replaced the battery.
If you want to know the battery health of your laptop, be aware that there are many applications on Windows 10 made specifically for this purpose.
Once you have determined the battery power of your laptop, you simply need to divide it by the duration (in hours) of your laptop when fully charged (100%):
Average power consumption (W) = battery energy (Wh) / usage time (h)
In our theoretical case, the battery of an Acer laptop is 44Wh and its charging time under normal daily use is typically 3.5 hours. Therefore, the average power consumption of our laptop will be:
Average Acer power consumption = 44 Wh / 3.5 h = 12.8 W (watts)
In addition
It's clear that our laptop's power consumption and battery life vary depending on the tasks being performed. For example, browsing the internet is nothing compared to playing a game that uses both the CPU and GPU of our PC to run at full capacity!
Computer battery life with an external battery:
Now that you have chosen your external battery, it's time to calculate approximately the theoretical time you will use your computer for a certain typical activity, whether it's watching series, office work, surfing the internet, playing online games… and also depending on the charging method: battery removed, computer turned off, or while using it at the same time:
Calculate the average power consumption of a laptop
- Check the average battery life (in hours) of the laptop with a fully charged battery, depending on the type of activity usually performed.
- Check the laptop battery power (Wh).
- Apply the formula: Average consumption (W) = battery energy (Wh) / usage time (h)
Calculate the usable energy of the external battery
- Check the energy (Wh) of the external battery.
- Calculate the energy required to use the computer and/or to recharge its battery, depending on the type of external battery:
- External DC or USB-C PD battery: Usable energy = External battery energy x 0.7225
- AC power bank: Useful energy = Power bank energy x 0.6141
Calculate the laptop's battery life
- Laptop battery removed:
- Usage time (h) = useful energy (Wh) / average consumption (W)
- Recharging the battery with the laptop turned off:
- Number of charges = useful energy (Wh) / PC battery energy (Wh)
