
CHARGING YOUR LAPTOP with a Power Bank

The ability to charge your laptop anywhere you are gives you the freedom to work and travel, without having to worry about empty batteries. Xtorm has several Power Banks that offer you just that. So what option is best for you? And how many times can they recharge your laptop?


USBC Power Delivery These days new laptops often have a USBC PD (Power Delivery) / Thunderbolt 3 port that is also used to charge the laptop. Our XB3 power banks are specifically designed to recharge your USBC PD laptop, wherever you are.
We have two XB3 power banks that can charge your laptop, with either a 45W, or 60W Power Delivery output. Which one suits you the best depends on the power requirements of your laptop. A simple way to check this is to look at the wall charger that came with your laptop.
Some laptops, like the 15” MacBook Pro, might require more than 60W of power. Our power bank will still work perfectly fine, although charging might be slower if your laptop is demanding a lot of power during a high workload.


AC Power USBC PD is great, but unfortunately not all laptops have it yet. That doesn’t mean there is no way for other laptops to be charged on the go. Xtorm offers two power banks, the AL480N and AL490, that both feature actual AC power outlets. This means you can plug in almost any device and charge it, including laptops!
The AL480N is a powerful yet relatively small power bank, which packs an 80W / 220V AC output. The AL490 features two 200W / 220V AC outputs, which is more than the AL480N has, but it’s also substantially larger in size.


How many times can I actually charge my laptop? This depends on several things, such as the capacity of the power bank, the battery size of your laptop, as well as the charging method. In order to best explain things we are going to have to get a bit more technical.
To find out how many times a power bank can recharge a laptop, you have to relate the capacity of the power bank to the battery size of a laptop. The best way to compare battery sizes is to use Wh (Watt hour).


What is Wh and why do we use it? Using Wh might seem strange, because normally when you’re shopping for power banks the capacities are often shown in mAh. This is because until recently most power banks were primarily designed to be used with smartphones, and since smartphone battery capacities are communicated in mAh it makes sense to also do this for power banks.
For example  The 2018 MacBook Pro 13” has a 5200mAh battery. When you compare this to modern day smartphones, which have capacities as high as 4500mAh, the laptop battery seems relatively small.
You might even be tricked into thinking that you could recharge that MacBook Pro almost 2x with a 10.000mAh power bank, which is not true. So why isn’t this the case for laptops as well? It has to do with the fact that the voltage of laptop batteries are a bit different than your typical smartphone battery. Using Wh solves this problem.
How can you find out what the Wh of a battery is? You can calculate it by multiplying the (m)Ah capacity of a battery with the Voltage. (Ah x V = Wh)
To make things easier Xtorm power banks mention the Wh rating on the box, as well as in the specifications. To find out the Wh capacity of your laptop’s battery you’ll have to check the manual or go online, to find the exact number


Let's get practical! So if we use the example from before – how many times could a 10.000mAh battery theoretically recharge that MacBook Pro? To do this we must find out how much Wh the power bank is.
First we need to convert the 10.000mAh to Ah for this calculation to work. The “m” in “mAh” stands for “milli”, so if we simply divide 10.000mAh by 1000 we get the correct number, which is 10Ah. The next part requires that we multiply that number with the voltage of the battery. A typical 10.000mAh power bank has a voltage of 3.7V.
This leads to the following calculation: 10Ah x 3.7V = 37Wh
If we compare this to the 58Wh battery of the MacBook Pro, it shows that the 10.000mAh power bank can only recharge the MacBook about 0.6x, so not even once! (37 devided by 58)
Luckily the batteries in our Xtorm Power Banks are much bigger. So how many times can Xtorm Power Banks recharge your laptop? Here are some examples so you can find out:

For USBC PD laptops: Take the Wh rating of the power bank, and multiply it by 0.9. (This is to correct for the 10% of power that’s lost during the charging process due to resistance. This is normal for all types of charging.) Then take that number and divide it by the Wh battery capacity of your laptop.
Quick example – The XB303 Power Bank Voyager has a capacity of 93.6Wh. You then take that number and multiply it by 0,9  so you get 93.6Wh x 0.9 = 84.24Wh.
If we compare this to the laptop we used before  the 2018 MacBook Pro 13” – it has a battery capacity of 58Wh. To find out how many times the XB303 can recharge this MacBook, simply divide the 84.24Wh by 58Wh. This shows it can recharge the MacBook Pro almost 1.5x!
Now you know how many times you can charge your laptop with the power bank.

For AC powered laptops: The method is basically the same as explained above, only now we correct the power bank Wh by multiplying it with 0,65. The reason for this is that around 35% of the energy is lost by converting battery power to 220V AC power.
So if we take a look at an example again – The AL480N Power Bank Brick has a capacity of 84Wh. If we correct this for the loss of energy during charging, we get 84Wh x 0.65 = 54.6Wh
If we use the same laptop as before  the 58Wh MacBook Pro 13”  we see that the AL480N can almost fully recharge the MacBook 1x.

It’s not something that’s very easy to understand at first, but once you do it makes navigating the battery and Power Bank landscape a whole lot easier. Now you know not to be fooled by mAh when it comes to charging your laptop!

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