When should I replace my mobile battery?

How to extend the battery life of smartphones and notebooks

Andreas Hitzig

We show you how you can maintain the service life of your battery, regenerate ailing batteries and save electricity.

EnlargeWe'll tell you the best tricks to save the battery and to get power even in emergency situations.
© Oleksiy Mark @ fotolia.de

Does the battery of your notebook or smartphone always run out too quickly? With our tips, your battery will last longer. First, we will provide you with tips on how to extend the battery life of smartphones. Then from the section "Part 2: How to extend the battery life of notebooks", there are many tips that will help you to work longer with your laptop while on the move.

Why is the capacity of your battery decreasing more and more?

The battery in notebooks and smartphones is subject to wear and tear: the longer it is in use, the less energy it can absorb, store and then transfer back to the mobile device. Batteries with lithium-ion technology, as they are currently used in almost all mobile devices, lose around half their capacity in around two years of operation. The battery life of the device is reduced accordingly. You cannot stop this aging process of the battery, but you can slow it down significantly with the right care measures.

When does the battery become a warranty claim? The battery is usually covered by a shorter warranty than the notebook or smartphone itself. A 12-month battery warranty with a device warranty of 24 months is normal. When a warranty claim occurs within this period differs from manufacturer to manufacturer: Apple guarantees, for example, with the iPhone that the battery capacity does not fall below 80 percent after 500 complete charging cycles, as does Samsung with the Galaxy smartphones. Often, however, there is no clear information about the capacity limits from which the battery guarantee applies.

Many manufacturers supply battery check tools that can check the battery status: only if they display an error within the warranty period, the battery is considered damaged and will be replaced free of charge.

Does a replacement battery have to come from the device manufacturer? You do not have to buy the new battery from the manufacturer - however, in the event of a complaint you have a better chance than from a third-party supplier. In addition, with a third-party battery you have to be sure that it actually fits your notebook, as described, because there are no public lists of the laptop manufacturers for the tested batteries for a specific model. In any case, you should exercise caution with conspicuously cheap offers, because there are always reports of counterfeit and inferior batteries that are sold as official spare parts by third parties.

How do you recognize the loss of capacity of your battery? First, charge the battery to 100 percent. Then install the free Passmark Batterymon tool. After starting the tool, click on the third icon from the left "Battery Information" and pay attention to the information in the lines "Design Capacity" and "Full Charge Capacity". The first indicates how large the capacity of the battery should be in milliwatt hours (mWh) according to the manufacturer, the second how high its current capacity is when fully charged. The difference is the loss of capacity. The battery capacity can also be checked with a Windows standard tool: Start the command prompt (e.g. via the Windows start menu) and enter the command powercfg / batteryreport in the command line. After pressing Enter, Windows will show you where it saved the “Battery Life Report” that you requested with this command. Open the HTML file with a double click: The relevant information is also available here under “Design Capacity” or “Full Charge Capacity”.

Tip:The best apps for your smartphone battery

1. How to extend the battery life of smartphones

Do you still remember the "memory effect" with nickel-cadmium batteries? He made sure that a few years ago there was only one rule for batteries: Always discharge the battery completely before charging, otherwise the battery will remember the status and no longer charge completely. This rule is now a thing of the past, and researchers have found that the opposite is true for the battery. On the next few pages we explain everything you need to know about battery care.

It helps to know the technical data of the battery. You can find them as a label or label directly on the device, such as "3.8 V Li-ion battery", "5.70 Wh" and "4.35 V". In our case, the lithium-ion battery has a nominal voltage of 3.8 volts, a capacity of 5.70 watt hours and an end-of-charge voltage of 4.35 volts. So you can charge the battery with a charger that provides between 3.8 and 4.35 volts.

In addition, its electrical charge in milliampere hours (mAh) is printed on a battery. It indicates, so to speak, the amount of electricity that can be drawn from the battery per hour. In practice, both this and the watt-hour value are referred to as "capacity".

1.1 General battery tips

One of two battery technologies is usually used in modern smartphones: lithium-ion or lithium-polymer. The difference lies in the electrolyte, which is liquid in lithium-ion batteries and consists of a gel-like polymer-based film in lithium-polymer versions. This means that lithium-polymer batteries are possible in various designs, even angled or bent. But no matter which battery powers your mobile device - there are a few basic rules that you should follow when using it.

1.2 Charge level and storage of the battery

Since a battery ages the faster the higher its cell voltage, you should not keep the power supply of your smartphone at 100 percent charge capacity all the time. In general, a 55 to 75 percent charge is believed to be optimal. In addition, you should keep the battery as cool as possible at 10 to 15 degrees. For comparison: at room temperature (around 20 degrees) a battery loses around 3 percent of its charge per month.

1.3 Charge your smartphone properly overnight

Many people hang their smartphone on the charger before going to bed so that it is available the next morning with a fully charged battery. Doing this can damage the battery. When your battery is fully charged during the night, the phone switches to mains operation. The background activities cost electricity, the battery level drops by a few percent, and the charger starts working again. These short charging cycles damage the battery and reduce its performance. To ensure a long battery life, you should therefore switch off the smartphone before charging.

If you use your smartphone as an alarm clock, this is of course not possible. In this case, it is best to charge the device to around 90 percent before you go to bed. Then put your phone in airplane mode. This will reliably wake you up the next day, but the battery level has only dropped slightly.

1.4 Charging the battery via USB or mains plug?

There are basically two classic methods of charging the smartphone: with the included USB cable via the USB socket on the PC or directly at the socket via a charging adapter and a USB cable or a charger. However, there are some key differences in terms of the charging speed: You can charge the fastest directly from the socket, or more precisely, about three times as fast as when charging via the USB port of the computer.

The reason: A USB 2.0 connection only delivers a maximum of 500 mA. Therefore, charging takes a correspondingly long time because the capacity of current smartphone batteries is much higher. With USB 3.0, the current has been increased to 900 mA, which means that you can charge the device slightly faster.

You should bear this in mind when charging: The optimal charging voltage for lithium-ion batteries is 4.2 volts. Most chargers with a charging voltage of around 5 volts are still within the tolerance range, which means that the batteries are not damaged. In addition, they usually pass a current between 700 and 1000 mA.

The charging current should also be approximately 0.6 to 1 times the battery capacity in mAh. Higher currents can reduce the service life of the battery, lower currents can overheat the charger.

1.5 How much do fast-charging technologies load the battery?

In the case of smartphones in particular, manufacturers often advertise fast charging techniques such as Fast Charging or Quick Charge, which are supposed to charge the battery in the shortest possible time. Basically, charging at high voltages and temperatures puts a strain on the battery. The smartphone manufacturers, on the other hand, point out that during fast charging they can regulate the voltage and current flow in such a way that no harmful temperatures arise for the battery. In addition, the battery is only charged very quickly up to a certain level, for example up to around 60 percent, so as not to burden the battery for a long time. However, the battery and charger must be suitable for the corresponding fast charging process.

EnlargeThe Sunnybag Powertab offers a practical solution for charging the smartphone battery. The A4 solar panel that can be set up with a 6000 mAh battery has a built-in reading lamp as a bonus.

1.6 Deep discharge - what to do?

Every battery has a so-called end-of-discharge voltage, i.e. a defined voltage at which the battery is automatically discharged. With lithium-ion batteries, the end-of-discharge voltage is usually around 2.50 volts, with lithium-polymer batteries it is 3.30 volts. However, since the value is specified by the manufacturer, it can also be different.

If the voltage falls below this value, one speaks of deep discharge. This condition can permanently damage the battery because it can cause copper bridges to form in the battery, which may cause a short circuit as soon as you want to recharge the battery.

Reasons for deep discharge can be a faulty charger or an outdated battery. However, it can also happen that the “automatic switch-off” of the battery does not work properly. If you want to put a deeply discharged battery back into operation, you should work extremely carefully for the reasons mentioned in order to avoid damage.

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Panasonic has developed a battery that is only 0.45mm thick and also bendable. This makes it suitable for flexible devices with bendable displays. So far, however, the capacity is still relatively low. Mass production is scheduled to start in 2018.

1.7 Correct handling of batteries in winter

The battery life is reduced at low temperatures. In order to keep the battery consumption of your mobile device as low as possible, it is worth checking the energy options of the smartphone and adjusting them if necessary. Then all unnecessary functions such as WLAN and Bluetooth are switched off, which unnecessarily shorten the battery life.

You can also increase battery life by putting your smartphone in a case with an extra battery. For example, there is the Mophie Juice Pack for the Samsung Galaxy S4, S6, S6 and the S6 Edge in different colors. Cost: between 100 and 110 euros. IPower is a special feature for some Samsung mobile devices