How to choose a portable battery

Every mobile phone manufacturer is trying to solve an impossible task – to give their brainchild maximum memory and performance, provide it with all possible options, but at the same time make it as light and thin as possible.

Unfortunately, they often try to solve this problem due to the capacity of the battery. Many modern smartphones keep a charge literally for a day, even if only “out of the box”.

And sooner or later a moment arises when you need to make an important call, or you are waiting for an important call, or you urgently need to get important information from the Internet, or … and the phone shows 0% charge and turns off. It’s good if charging is at hand and there is a power outlet nearby, but what if not?

The lifebuoy in such a situation will be a portable battery (power bank).

The disadvantage of a portable battery is that it introduces additional difficulties into our life, which is already loaded with care for various gadgets: it must be recharged on time, do not forget to put it in a bag or backpack; it is inconvenient to carry it in your pocket – heavy, etc.

There are smartphones on sale with a large-capacity battery that can hold a charge for several days or even weeks.

But, firstly, for many smartphone models there are simply no analogues with large batteries.

Secondly, “long-lived” smartphones are heavy and bulky.

Thirdly, the presence of a large-capacity battery does not guarantee that one day you will not find yourself “in an open field” with a discharged phone in your hands. On the contrary – the long life of such models on one charge gives a false feeling of “eternal” charge and they turn off somehow quite unexpectedly.

The portable battery also has some advantages over the built-in one, in addition to the fact that it keeps the smartphone lightweight:

  • it can charge not only smartphones, but also other mobile devices powered by USB
  • some models have additional functionality: a flashlight, solar battery, card reader, etc., which greatly expands the scope of their application.

Characteristics of portable batteries

The capacity of a portable battery is its main parameter, which primarily determines its attractiveness and price. The larger the battery capacity, the more times it will be able to fully charge a smartphone or other gadget.

But, before buying a battery for several tens of thousands of mAh, you should assess whether such a capacity will really be in demand.

If the battery is needed only to be able to use a suddenly “dead” phone in a critical situation, then the minimum capacity battery will suffice – it will be easier, more convenient to use, and much cheaper.

If you plan to use the battery while traveling, it is better to take a power bank with a capacity that will be enough for several full charges of the smartphone.

And if it is planned to charge not only a smartphone with a battery, but also other gadgets – up to a laptop, then there will be no extra capacity here.

When choosing a capacity, one important point should not be overlooked: not all of the capacity of a portable battery is capable of “going” into the battery of a rechargeable gadget.

The number given on the case of the bank is the nominal value. Such a capacity will be given by its elements when they are discharged with a rated current. And in real operation, the discharge currents are much higher, plus often the discharge is performed at a voltage exceeding the nominal value of the elements from which the battery is assembled – and part of the energy is also lost during the conversion.

Plus, we must not forget that lithium-ion batteries (which make up most portable batteries) “do not like” full discharges – part of the charge should be left in the battery, otherwise it will quickly fail.

Taking into account all these features, the working capacity of the battery – the one that it can transfer to the charged devices – is 60-70% of the nominal. And the more current and voltage the charge is produced, the less this percentage.

The output voltage should be selected based on the characteristics of the device being charged.

The output voltage of 3.7 (3.8) V can be used to charge most battery cells, the nominal value of which is just 3.7 V. Moreover, the cells can be charged directly with this voltage, without a charging controller.

The advantage of power banks with an output voltage of 3.7 volts is that their efficiency is slightly higher due to the lack of conversion of the output voltage.

And the disadvantage is that their versatility is limited – the standard supply voltage at the USB connector (which most of these batteries are equipped with) is 5 V, and if you try to charge with it a device whose charging controller requires exactly 5 V, then the device will simply refuse to charge …

The 5V output voltage is the USB power standard used to charge most mobile devices today. Unsurprisingly, this output voltage is the most common on portable batteries and the most versatile. Any device with USB charging is simply required to be charged from a 5V connector.

Output voltages of 9, 12, 16, 19 and 20 V on a separate connector are designed to charge larger mobile devices, most often laptops and tablets.

Usually, the voltage at the connector is set by a button on the case of the power bank, and the connection to the charged device is made using the appropriate adapter.

Before charging devices with such a battery, you should carefully make sure that the voltage is set correctly and the adapter is installed appropriately – otherwise, damage to the charged device may occur. It is not at all superfluous for such a model to have a display on which the charging voltage is displayed.

It also happens that output voltages greater than 5 V are given in the characteristics of a battery that has only USB output connectors. The USB 3.1 standard allows a supply voltage of up to 20 V – but this voltage is set only automatically and only after the charged device “informs” the charging that it is ready to receive an increased voltage.

If the USB power supply voltage on the battery can be set manually, then it is better to refuse such a power bank – the risk of “burning” the charged device is too great.

Current strength (output). The amperage determines the suitability of the battery for charging tablets and laptops (many of them require charging currents from 2 to 4 A) and also shows how quickly the power bank can charge the phone.

A battery with a maximum output current of 0.5 A will charge the smartphone twice as long as a battery with a current of 1 A. If the smartphone is capable of charging with a current of 2 A, then the charging time (from the corresponding battery) will be halved.

At the same time, do not be afraid to “burn” the smartphone with an increased charging current – for all modern phones, the controller limits the charging current to the optimal value.

The advantage of a power bank with a low output current is one – such a discharge mode is more favorable for the battery and its working capacity will be higher than that of a power bank with a similar nominal capacity, but a high output current.

Supports fast charging. Many modern gadgets are able to speed up charging times by 40-50% by using the USB 3.1 power supply voltage and current capabilities.

In fast charging mode, the controller monitors the parameters of the battery being charged and sets the voltage and current on the connector, which are optimal for accelerating the charge. Different manufacturers use different fast charging standards, and if this feature is important to you, make sure that the battery supports the same fast charging mode as your smartphone before purchasing a battery.

Compatibility. Most portable batteries are universal and suitable for charging any gadget with the appropriate connector. But if you want to be sure that the battery has the right connector and supports all charging modes of your gadget, choose among compatible models.

Battery type. Lithium-ion (li-ion) batteries are made up of standard cells (looking like finger-type batteries), they are relatively inexpensive, but are susceptible to self-discharge and get very hot at high currents.

Lithium polymer batteries are more powerful, safer, but also more expensive.

The output connectors on the case are used to charge devices, it is advisable to choose a battery with those connectors that you may need.

Most devices, if not directly charged from USB, have an adapter for it, so the USB output connector is the most common. A miniature version of this connector, microUSB, is also common.

Recently, the USB Type-C connector has become more widespread – many devices with fast charging support have just such a charger connector.

Well, we must not forget about Apple devices, which traditionally avoid generally accepted standards: if you are the owner of an iPhone or iPad, to charge you will need a portable battery with the appropriate output connector – apple 30-pin or apple Lightning.

The input connectors on the case are used to charge the battery itself. Some batteries have their own power supply unit with a separate connector, most are charged from the same USB / microUSB.

Owners of Apple technology may find it more convenient to use a battery that uses a Lightning connector for charging – such a battery can be charged with a regular Apple charger.

The number of USB ports is more than 1, which can be useful if you plan to charge multiple devices at the same time.

But keep in mind that the battery will most likely not be able to handle the maximum output current on all connectors. The battery output current is “divided” by the connectors used: if to a battery with a maximum output current of 2 A.