For many, the smartphone is the most important everyday companion. The device must therefore be charged regularly if it is used continuously. But how expensive is that actually?
With electricity prices still high, it’s good to have an overview of the precise breakdown of costs. The big power guzzlers in the home are easy to identify: televisions, computers, but above all household electronics such as refrigerators or washing machines. However, it is less clear how much it costs to charge a smartphone.
As is well known, it is easy to save electricity by always unplugging the charger from the socket after charging the mobile phone. This is because the chargers also consume electricity even when they are on standby. The costs for several chargers add up quickly. But how much does it actually cost to fully charge a smartphone? TECHBOOK calculates it.
This is how you calculate the cost of charging your smartphone
Of course, it is not possible to say in concrete terms how high the costs for charging a specific smartphone are. That depends above all on the battery capacity of the respective device and of course also on the current electricity costs. You also have to take into account that a certain part of the energy is released into the environment when charging; this is called efficiency. However, if you add these factors together, you can determine quite precisely how expensive it really is to charge a smartphone.
The formula for this is:
Electricity price x efficiency x battery capacity = cost of charging a smartphone in cents
At the moment (April 2023), the average electricity price is 34.96 cents per kilowatt hour (kWh). To find out how much you’re paying personally, you’ll need to check with your electricity supplier. through the energy price brake the costs for private consumers are limited to 40 cents per kilowatt hour. Only those who come to more than 80 percent of the consumption expected on the basis of the previous year have to reckon with higher costs. The price brake is still valid for the whole of 2023.
So the first factor in our calculation is 34.96, so the formula is: 34.96 x efficiency x battery capacity
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Loss of energy from heat
It should be noted that electricity from the socket does not reach the smartphone 100 percent. A not inconsiderable part of the energy is lost in the form of heat. While wired charging is quite efficient – i.e. less heat is generated – things look a little different with inductive charging without a cable. On average, 20 percent of the energy is lost when charging with a cable. However, this depends heavily on the quality of the charger, because higher efficiency is definitely possible.
With wireless charging, on the other hand, the energy loss is significantly higher. The reason for this is the way inductive charging works. The charging station generates a magnetic field through a cable coil. This is picked up by another coil in the smartphone and an electrical AC circuit is created. The advantage is that this type of charging works even without direct contact of the coils and even penetrates objects such as cases or tabletops.
However, the downside is that this technology uses more energy than wired charging. The greater the distance between the coils, the more electricity is converted into heat instead of ending up in the smartphone battery. As a result, wireless charging tends to be slower as well. In addition, the higher temperatures during charging can have a negative effect on the battery. There are now a number of approaches to reducing energy loss. Apple, for example, uses magnets in its MagSafe chargers for iPhones to align the coils perfectly, thus avoiding losses due to inaccurate positioning.
While we leave wireless charging out of our calculations, you can calculate the cost by factoring in about 50 percent energy loss instead of 20 percent. In the formula, we express the 20 percent energy loss as a factor of 1.25. The calculation is now: 34.96 x 1.25 x battery capacity
You have to take this into account when calculating the battery capacity
To find out the battery capacity of your own smartphone, a look at the technical data sheet is often enough. When determining the capacity for the calculation, however, you should definitely pay attention to the unit. This is given in either watt hours (Wh) or milliampere hours (mAh). However, the statement in watt hours is necessary for the calculation, since that is also the unit for the electricity price.
Another factor plays a decisive role in the conversion from mAh to Wh – namely with which voltage (Volt, abbreviated V) the smartphone battery works. The formula for this is (mAh)*(V)/1000 = (Wh). For example, if you have a 3000 mAh battery with 5 volts, the capacity is 15 watt hours.
It should be noted that the smartphone battery does not always operate with the same voltage. The specified voltage is only the nominal value. In fact, a battery has a higher voltage when it’s full and a lower voltage when it’s running low. Therefore, to simplify the calculation, we only use the nominal voltage.
In addition, of course, how full or empty the battery actually is and how long it has to be charged accordingly also plays a role for an exact calculation. In addition, the energy consumption varies during the charging process. Initially, the consumption is higher, towards the end it decreases. So if you always unplug after the first 20 minutes and repeatedly charge in this way, you will use more electricity. Our calculation therefore refers to a full battery charge – i.e. from 0 percent to 100 percent of the capacity.
For our formula, we have to divide the watt-hour figure by 1000 to convert it back to kilowatt-hours. This brings us to: 34.96 x 1.25 x (Wh/1000). Slightly rearranged, the formula is: 34.96xWh/800.
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Calculation examples for the costs of smartphone charging
With the three factors electricity price, approximate efficiency and battery capacity, we can now calculate how much a single smartphone charge per cable costs. Simply enter the specified battery capacity in watt hours into the formula and you’re done!
Example: Apple iPhone 14 Pro Max
The iPhone has a capacity of 16.68 Wh. Put into the formula it looks like this: 34.96 x 16.68 / 800 = 0.73. A complete battery charge costs around 0.73 cents.
Example: Samsung Galaxy S23 Ultra
With 18.88 Wh battery capacity in the Galaxy S23 Ultra, our formula gives the following result: 34.96 x 18.88 / 800 = 0.82. A charge from 0 to 100 percent is 0.1 cents more expensive for the S23 Ultra than for the iPhone 14 Pro Max.
Example: Google Pixel 6
The Pixel 6 with a capacity of 17.46 Wh sits between the iPhone 14 Pro Max and the Galaxy S23 Ultra. This value gives the following result: 34.96 x 17.46 / 800 = 0.76. A full charge of the Pixel 6 costs 0.76 cents.
Individual costs for smartphone charging are low
The calculation examples show that it is very cheap to charge a smartphone. Even with the Galaxy S23 Ultra, which consumes around 0.82 cents of electricity per charging process, the annual costs are just under 3 euros – even with daily full charging, which is extremely rare.
Nevertheless, the numbers should be viewed critically. According to Statista forecasts, there will be 6.9 billion active mobile subscriptions for smartphones by 2023. This does not correspond one to one to the number of devices actually used, but at least gives us an order of magnitude. The cost of charging smartphones is therefore not an individual problem, but a societal problem.
source
- Eco test: “How much does it actually cost to charge your cell phone? 75 cents, 7.5 cents or 0.75 cents?” (accessed April 18, 2023)