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Powerbank review - 03/2020

You know the problem: on the go all day, rushing from one appointment to another and no time to recharge your smartphone - at the latest in the afternoon or evening the battery gives up. In many cases, when you need it the most. These Powerbanks can prevent this and save your day!

We have tested Powerbanks of different capacity classes for you and will tell you which ones are best suited for you.

Power Banks

Tested products

RAVPower 10000mAh	 - thumbnail Test seal: RAVPower 10000mAh	, Rating good

1st place: RAVPower 10000mAh

With the RAVPower 10.000 mAh a very good percentage of the capacity can be used. On the other hand, it is somewhat larger and heavier than its competitors. It also convinces with its short charging time and low heating. Only the workmanship of the case stands out negatively. So if you place more value on performance than on looks, this power bank is a very good choice.

read review
Anker PowerCore II 10000mAh	 - thumbnail Test seal: Anker PowerCore II 10000mAh	, Rating good

2nd place: Anker PowerCore II 10000mAh

The Anker PowerCore II is a very compact and high-quality power bank. It convinces especially by its short charging time thanks to its Quick-Charge function and is able to supply 9 V and 12 V devices. The low usable capacity as well as the lack of a possibility to be charged by itself while charging another device are negative aspects. In addition, the Anker power bank has only one output. But if that does not bother you, this product is a good power bank.

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Intenso Slim S10000 - thumbnail Test seal: Intenso Slim S10000, Rating good

3rd place: Intenso Slim S10000

The Intenso S10000 is a solid power bank with slight flaws in its workmanship. A positive aspect is the portion of usable capacity. This power bank has only one USB output, but together with the integrated micro-USB cable, two devices can be charged simultaneously. All in all, this product convinced us in our tests.

read review
Realpower PB-10000C 10000mAh	 - thumbnail Test seal: Realpower PB-10000C 10000mAh	, Rating satisfactory

4th place: Realpower PB-10000C 10000mAh

The RealPower 10.000 mAh has 3 outputs and can, therefore, load up to three devices simultaneously. It can also be charged and discharged simultaneously. However, the power bank heats up strongly during discharge and the long charging time is also noticeable negatively. Despite overload protection, this power bank allows a significantly too high output current, which can lead to long-term damage to the device. Unfortunately, this product mainly stands out negatively due to these characteristics.

read review
Winner
Our winner: RAVPower 10000mAh	Anker PowerCore II 10000mAh	 Review Intenso Slim S10000 Review Realpower PB-10000C 10000mAh	 Review

RAVPower 10000mAh

Anker PowerCore II 10000mAh

Intenso Slim S10000

Realpower PB-10000C 10000mAh

Test seal: RAVPower 10000mAh	, Rating 1.85
Test seal: Anker PowerCore II 10000mAh	, Rating 2.15
Test seal: Intenso Slim S10000, Rating 2.25
Test seal: Realpower PB-10000C 10000mAh	, Rating 3.1
  • 92% of capacity usable
  • Low heating
  • Short charging time
  • Short charging time thanks to quick-charge
  • Compact design
  • Can supply 9 V and 12 V at the output
  • Integrated charging cable
  • 87% of capacity usable
  • 3 outputs
  • Charge status is shown on the display
  • Defects in the processing of the housing
  • Heavy
  • Only one output
  • Only 78% of capacity usable
  • Strong heating during discharging
  • 2.6 A maximum current
  • Strong heating
  • Long charging time
  • Overload protection intervenes late
  • Voltage drop during discharge

High usable capacity and short charging time. However, there are minor deficiencies in its workmanship.

Compact power bank, but only one output and only 78% of the capacity usable.

Reliable power bank, but small flaws in workmanship and strong heating during discharging.

Satisfactory power bank with problems with overload protection and voltage drop during discharge.

Range of functions
Size capacity ratio
Usable capacity
Workmanship
Scope of delivery Power bank, 2 x charger cables (USB to microUSB; 65 cm & 27 cm), manual, bag Charging cable ( USB -> microUSB, 60 cm), bag, manual Powerbank, manual, charging cable (USB to microUSB, 45 cm) 2 x charging cables (USB -> microUSB, USB -> USB - C; 20 cm x 20 cm), manual
Quality impression Satisfactory Very good Good Good
Inlets Micro-USB (5V/2A max) Micro-USB (5V/2A, 9V/2A) Micro-USB (5V/2,1A) 1x Micro-USB (5V/2,1A), 1x USB-C (5V/2,1A)
Outlets 2x USB (Total 5V/3.4A, each individually max. 5V/2.4A) 1x USB (5V/3A, 9V/2A, 12V/1.5A) 1x Micro-USB (5V/2,1A) with integrated cable, 1x USB (5V/2,1A) 1x USB (5V/2,1A), 1x USB(5V/1A), 1x USB-C (5V/2,1A)
Charge indicator 3 - level LED charge indicator 8 LED 4 LED - charge indicator Display - charge level indicator
Capacity (manufacturer) 10.000 mAh 10.000 mAh 10.000 mAh 10.000 mAh
Capacity (measured) 9.190 mAh 7.840 mAh 8.714 mAh 8.200 mAh
Charching time 4:30 hrs 3:30 hrs 6:34 hrs 7:40 hrs
Additional warranty 18 months 18 months 2 years 12 months
Height 11 cm 9,6 cm 13 cm 10,9 cm
Width 8 cm 6,2 cm 7 cm 7,5 cm
Depth 2,2 cm 2,2 cm 1,6 cm 2,2 cm
Weight 256 g 191 g 205 g 230 g
Simultaneous charging and discharging Yes No Yes Yes
Loading several devices in parallel Yes, 2 No Yes, 2 Yes, 3
Button Yes Yes No button Yes
Packaging Plain, made of cardboard Informative, magnetic closure Informative, magnetic closure Informative, magnetic closure
Quality of instructions Short, simple, QR Code leads to online manual Short Detailed Short, understandable
Manual language EN, GER, FR, ES, IT, JP GER, EN, FR, IT, ES, JP, RU, AR, ZH GER, EN, FR, NL, IT, ES, PT, CZ, HR, PL, SK, HU, RU GER, EN, FR
☆☆☆☆☆
★★★★★
512 reviews
☆☆☆☆☆
★★★★★
995 reviews
☆☆☆☆☆
★★★★★
8 reviews
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*All prices include VAT (if applicable, extra charge for delivery. Check the particular online shop to find information about the availability. Changes of indicated prices since the last update remain reserved.

Tested products

Intenso Powerbank PM5200 - thumbnail Test seal: Intenso Powerbank PM5200, Rating good

1st place: Intenso Powerbank PM5200

The Intenso PM 5,200 mAh convinces with its high usable capacity and low heating. With its handy design, it is well suited for travelling. However, it must be noted that the Powerbank can only deliver 1.5 A at the output.

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RAVPower 6700mAh - thumbnail Test seal: RAVPower 6700mAh, Rating good

2nd place: RAVPower 6700mAh

The RAVPower 6.700 mAh with its slim metal housing is of high-quality workmanship and fits well in your pocket. Also, the heat development during charging and discharging is very low. The long charging time and the low usable capacity are negative, though. Verdict: on the whole a solid power bank.

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Anker PowerCore 5000mAh - thumbnail Test seal: Anker PowerCore 5000mAh, Rating good

3rd place: Anker PowerCore 5000mAh

The Anker PowerCore 5000mAh convinces with its elegant design and high usable capacity. Due to its size, it is well suited for travelling and fits in your pocket. However, the strong warming of the Powerbank during charging and discharging is noticeable negatively. Conclusion: all in all a solid power bank.

read review
POWERADD Slim 2 5000mAh - thumbnail Test seal: POWERADD Slim 2 5000mAh, Rating satisfactory

4th place: POWERADD Slim 2 5000mAh

The Poweradd Slim 2 is a satisfying power bank for on the road with some processing flaws. It also stands out for its low usable capacity and noticeable warming during charging and discharging.

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RAVPower 5000mAh Powerbank - thumbnail Test seal: RAVPower 5000mAh Powerbank, Rating satisfactory

5th place: RAVPower 5000mAh Powerbank

The RAVPower 5000 mAh is well-manufactured, but because of the low usable capacity and the strong heating, this product could not convince in our test. The charging time is acceptable.

read review
POWERADD EngeryCell 5000 - thumbnail Test seal: POWERADD EngeryCell 5000, Rating satisfactory

6th place: POWERADD EngeryCell 5000

The Poweradd EnergyCell is a very slim and solidly processed power bank. The low warming under load is positively noticeable. The biggest disadvantage of this Powerbank, however, is that only 64% of the capacity is actually usable. This fact should be taken into account when deciding on a purchase.

read review
Winner
Our winner: Intenso Powerbank PM5200 RAVPower 6700mAh Review Anker PowerCore 5000mAh Review POWERADD Slim 2 5000mAh Review RAVPower 5000mAh Powerbank Review POWERADD EngeryCell 5000 Review

Intenso Powerbank PM5200

RAVPower 6700mAh

Anker PowerCore 5000mAh

POWERADD Slim 2 5000mAh

RAVPower 5000mAh Powerbank

POWERADD EngeryCell 5000

Test seal: Intenso Powerbank PM5200, Rating 2
Test seal: RAVPower 6700mAh, Rating 2.15
Test seal: Anker PowerCore 5000mAh, Rating 2.25
Test seal: POWERADD Slim 2 5000mAh, Rating 2.6
Test seal: RAVPower 5000mAh Powerbank, Rating 2.9
Test seal: POWERADD EngeryCell 5000, Rating 3.3
  • 85% of capacity usable
  • Short charging time
  • Low heat generation
  • Pass-through charge
  • Constant power
  • Low warming
  • Pass-through charge
  • Constant power
  • Short charging time
  • Constant power
  • 80% of capacity usable
  • Fast loading time
  • Pass-through charge
  • Constant power
  • Continuous charging
  • Low warming
  • Continuous charging
  • Constant power
  • Only 1.5 A at output
  • Late switch-off on overload
  • Only 72% of capacity usable
  • Long charging time
  • Strong heating during charging and discharging
  • No continuous charging
  • Poor processing
  • Only 70% of capacity usable
  • Significant warming during unloading
  • Strong warming
  • Low usable capacity
  • Power drop after 30 min
  • Very low usable capacity

Well-processed power bank with high usable capacity and low heating. But only 1.5 A at the output.

Metal housing and low heating during charging and discharging. However low usable capacity and long charging time.

A handy power bank with high usable capacity. However, strong heating and no continuous charging.

Deficiencies in processing and low usable capacity. Additional significant warming during unloading.

Power bank with low usable capacity and strong heating.

Solid power bank with very low usable capacity. But very thin and low heating.

Range of functions
Size capacity ratio
Usable capacity
Workmanship
Inlets Micro-USB (5V/2A) Micro-USB (5V/2A) Micro-USB (5V/2A) Micro-USB (5V/2A) Micro-USB (5V/2A) Micro-USB (5V/2A)
Outlets USB (5V/1.5A) USB (5V/2A) USB (5V/2A) USB (5V/2.1A) USB (5V/2A) USB (5V/2A)
Capacity (manufacturer) 5.200 mAh 6.700 mAh 5.000 mAh 5.000 mAh 5.000 mAh 5.000 mAh
Capacity (measured) 4.400 mAh 4.810 mAh 4.045 mAh 3.500 mAh 3.556 mAh 3.223 mAh
Charching time 2:50 hrs 4:40 hrs 2:45 hrs 2:39 hrs 3:15 hrs 3:25 hrs
Simultaneous charging and discharging Yes Yes No Yes Yes Yes
Additional warranty 2 years 18 months 18 months with limited liability 1 year 18 months 24 months warranty
Scope of delivery Powerbank, charging cable 25 cm (USB to microUSB), manual Powerbank, charging cable 65cm (USB to microUSB), bag, manual Powerbank, charging cable 60cm (USB to microUSB), bag, manual Powerbank, manual, charging cable 30 cm (USB to microUSB) Powerbank, charging cable 65 cm (USB to microUSB), bag, manual Powerbank, charging cable, bag, operating instructions
Height 9.6 cm 8.9 cm 10.8 cm 10 cm 10.7 cm 11 cm
Width 4.2 cm 4.2 cm 3.3 cm 3.3 cm 3.4 cm 2.7 cm
Depth 2.5 cm 2.2 cm 3.3 cm 3.1 cm 3.3 cm 2.7 cm
Weight 129 g 148 g 133 g 125 g 133 g 100 g
Quality of instructions Detailed Very short, satisfactory Short, informative, sufficient Short, informative, sufficient Short, sufficient Good
Manual language GER, GB, FR, NL, IT, ES, PT, CZ, HR, PL, SK, HU, RU GER, GB, FR, ES, IT, JP GER, ES, FR, IT, JP, AR, ZH GER, FR, GB, JP GER, GB, FR, ES, IT, JP GER, GB, JP, FR, ES, IT
Quality impression Good Very good Good Satisfactory Good Very good
Packaging illustrated, informative Good, solid Cardboard, plain Cardboard, Powerbank has spce for movement in packaging Cardboard, plain Good
Button Yes Yes Yes Yes Yes Yes
Loading several devices in parallel No No No No No No
Charge indicator 4 LED - charge indicator 4 LED - charge indicator 3 LED - charge level indicator 4 LED - charge indicator 4 LED - charge indicator 4 LED - charge indicator
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*All prices include VAT (if applicable, extra charge for delivery. Check the particular online shop to find information about the availability. Changes of indicated prices since the last update remain reserved.

Tested products

RAVPower 10000mAh - thumbnail Test seal: RAVPower 10000mAh, Rating good

1st place: RAVPower 10000mAh

The RAVPower Solarpowerbank is a solid and handy powerbank with a usable capacity of 83 percent. The maximum current of 2.1 A is a bit low, but overall this device was convincing in our tests.

read review
OUTXE 20000 mAh  - thumbnail Test seal: OUTXE 20000 mAh , Rating good

2nd place: OUTXE 20000 mAh

The OUTXE 20000 mAh is a robust and high quality manufactured Powerbank. It convinces with its high usable capacity of 87 percent and an 18 W output. The maximum current is also sufficient to easily charge two devices in parallel, and the integrated flashlight is very bright. The only negative thing that stands out is that this powerbank is somewhat unwieldy due to its size.

read review
POWERADD Apollo 12000mAh - thumbnail Test seal: POWERADD Apollo 12000mAh, Rating good

3rd place: POWERADD Apollo 12000mAh

The POWERADD Apollo has some flaws in the workmanship, but otherwise it is a solid powerbank. The usable capacity of this model is 85 percent and the powerbank also has an integrated cigarette lighter and flashlight. This makes it well suited for outdoor activities. The rubber caps in front of the inlets and outlets also reliably protect the connections from water entering.

read review
AKEEM 24000 mAh - thumbnail Test seal: AKEEM 24000 mAh, Rating satisfactory

4th place: AKEEM 24000 mAh

The biggest disadvantage of the AKEEM 24.000 mAh Powerbank is the very low usable capacity of only 58 percent. Although the device has three outputs, these cannot be used in parallel in practice due to the low maximum current. The charging time is okay, but overall this powerbank couldn't convince us in our tests.

read review
RLERON 25000mAh - thumbnail Test seal: RLERON 25000mAh, Rating satisfactory

5th place: RLERON 25000mAh

The biggest criticism of the RLERON Solarpowerbank is the disappointing usable capacity of only 58 percent. Although the device has three outputs, these cannot be used in parallel in practice due to the low maximum current. The good workmanship andthe bright flashlight stand out positively. Overall, this power bank wasn't convincing in our tests, though.

read review
Winner
Our winner: RAVPower 10000mAh OUTXE 20000 mAh  Review POWERADD Apollo 12000mAh Review AKEEM 24000 mAh Review RLERON 25000mAh Review

RAVPower 10000mAh

OUTXE 20000 mAh

POWERADD Apollo 12000mAh

AKEEM 24000 mAh

RLERON 25000mAh

Test seal: RAVPower 10000mAh, Rating 1.85
Test seal: OUTXE 20000 mAh , Rating 1.9
Test seal: POWERADD Apollo 12000mAh, Rating 2.2
Test seal: AKEEM 24000 mAh, Rating 3.15
Test seal: RLERON 25000mAh, Rating 3.3
  • High usable capacity
  • Loading time
  • Handy design
  • 87 percent of capacity usable
  • High maximum current
  • Waterproof
  • 85 percent of capacity usable
  • Waterproof
  • Integrated cigarette lighter
  • 3 outputs
  • 3 outputs
  • Bright flashlight
  • Low maximum current
  • Long charging time
  • Bulky
  • Long charging time
  • Poor processing
  • Only 58 percent of capacity usable
  • Low maximum current
  • Charge level display unintuitive
  • Only 57 percent of capacity usable
  • Low maximum current
  • Long charging time

Good powerbank with high usable capacity.

Good outdoor power bank with high usable capacity.

Good outdoor power bank with high usable capacity and integrated cigarette lighter.

Disappointing powerbank with very low usable capacity.

Well made powerbank with very disappointing usable capacity.

Workmanship
Range of functions
Size capacity ratio
Usable capacity
Scope of delivery Powerbank, 2x charging cable (Mirco-USB), operating instructions Powerbank, 2x charging cable (USB and USB-C), 2x carabiner, 2x loop, safety instructions (English) Powerbank, charging cable (Micro-USB), carabiner, operating instructions Powerbank, charging cable, manual Powerbank, charging cable (Micro-USB), manual
Inlets Micro-USB (5 V / 2.1 A) 1x USB-C (5 V / 3 A), 1x Micro-USB (5 V / 2 A) Micro-USB (5 V / 2 A) 1x Micro-USB (5 V / 2.1 A), 1x Iphone (5 V / 2.1 A) Micro-USB (5V / 2.4 A), USB-C (5V / 2.4 A)
Outlets 2x USB (je 5 V / 2.1 A) 1x USB (5 V / 3 A, 9 V / 2 A, 12 V / 1.5 A), 1x USB (5 V / 2.4 A) 2x USB (je 5 V / 2.4 A) 3x USB (je 5 V / 2.4 A) 3x USB (je 5 V / 2.4 A)
Capacity (manufacturer) 10,000 mAh 20,000 mAh 12,000 mAh 24,000 mAh 25,000 mAh
Capacity (measured) 8,324 mAh 17,495 mAh 10,176 mAh 13,990 mAh 14,210 mAh
Power consumption solar 1 W 2 W 1.65 W 1 W 1 W
Simultaneous charging and discharging Yes Yes No Yes Yes
Charching time 5:20 hours 10:00 hours 7:00 hours 8:30 hours 9:10 hours
Loading several devices in parallel Yes, 2 Yes, 2 Yes, 2 Yes, 3 Yes, 3
Solar cell size 12.5 x 6 cm 15 x 6.5 cm 12.5 x 6 cm 14 x 6.5 cm 12.5 x 6.5 cm
Button Yes Yes Yes (extra button for flashlight) Yes Yes
Flashlight Yes Yes, 3 modes (normal, dimmed, SOS) Yes, 3 modes (normal, SOS, flashing) No Yes
Waterproof No Yes, IP66 Yes, IPX7 No No
Height 17 cm 17 cm 17.6 cm 16 cm 16 cm
Width 8.6 cm 8.6 cm 11.2 cm 8 cm 8 cm
Depth 1.7 cm 3 cm 2.5 cm 2 cm 2 cm
Weight 278 g 549 g 340 g 377 g 362 g
Quality impression Good Excellent Good Satisfactory Good
Additional warranty 18 months 18-months warranty 24 months 24 months 24 months
Packaging Excellent Satisfactory Satisfactory Good Good
Quality of instructions Good Excellent Satisfactory Good Satisfactory
Charge indicator 4 LED charge level display 6 LED charge level display 4 LED charge level display LED strip Graphical display
Manual language GER, EN, FR, ES, IT, JP GER, EN, IT, JP GER, EN, JP, FR, ES, IT GER, EN, JP GER, EN, FR, IT, ES, JP
- - - - -
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*All prices include VAT (if applicable, extra charge for delivery. Check the particular online shop to find information about the availability. Changes of indicated prices since the last update remain reserved.

Despite some criticism and certain aspects that you should consider when buying solar powerbanks, there are quite a few areas of application where these chargers can be quite useful. For example, if you leave your battery unused but charged for a long time, it is likely that it will lose its stored energy.

This can lead to the battery not being ready for use when you really need it. However, if the battery is equipped with some solar cells, then you can extend the storage time considerably, as you will simply have to place the device in the sun again and again to recover energy. This way the battery will always remain fully charged and is ready to be used at any time.

It is also highly recommended that you buy a solar power bank if the electronic devices you want to charge with it require very little power. A smartphone usually requires too much energy for the sun to charge it in a short time alone. However, if you only need a solar power bank for electronic devices that require very little power to charge, such as iPods, this strategy can work very well.

Fully charging with the solar panel is extremely time consuming, but charged solar power banks can hold their charge very well during longer storage periods.

As mentioned above, a solar powerbank can be especially suitable for people who often worry and want to be prepared in case of an emergency. If you need the solar powerbank only in an extreme emergency and it is not used otherwise, this can be a good protection. So you can make an emergency call in an emergency situation, when the battery is already dead.

Also solar chargers are not only suitable for travelling. If you are an environmentally conscious person and you are concerned about saving electricity, then a solar charger is not only suitable for you outside when you are on the move. Although you cannot generate large amounts of electricity with it.

But it's a start on how you can protect the environment and your wallet. If you have bought a solar charger, you should not hesitate to use it at home. This way, you can always supply your mobile phone with solar energy free of charge.

However, you will need to find a place for the solar charger where it gets plenty of sunshine so that it can supply a lot of power. Because without sun, even the best and largest solar charger cannot collect energy. It is therefore important that you place the device in the sunniest place.

You do not need to know much about the function to use these devices. The principle of a solar powerbank remains the same as with a conventional powerbank. You charge it to be able to benefit from it later on the road and to extend the battery life of your devices.

Solarpowerbanks have solar cells on their surface. These ensure that the sun's rays are transformed into electricity for you. These solar chargers also usually have an integrated battery to store the energy.

So you can use them at a later time to charge your electronic devices. In theory, this should also be possible with other light sources. For example, you should be able to charge solar power banks with LEDs.

However, this usually takes much longer than putting the Powerbank in the sun. Therefore you should always charge a solar powerbank with solar energy.

Basically solar chargers can be divided into two different categories. There are pure solar chargers and solar chargers with rechargeable battery.

Pure solar chargers draw their power solely from solar energy by converting the sun's rays into electricity and then feeding it into the smartphone. So you can use these devices to charge your smartphone or tablet anytime, anywhere, without the need for a power outlet.

All you need is a little bit of sun. This gives you much more flexibility and means you don't always have to rely on power sockets. But also in times of climate and environmental protection, these devices are very suitable to fill up with energy for the electrical system.

In addition, solar chargers without rechargeable batteries with identical performance and number of solar cells are usually a little smaller and not as heavy as solar chargers with rechargeable batteries. This is because the battery contributes a lot to the weight. In addition, pure solar chargers are also cheaper than those with built-in rechargeable batteries.

However, there is no alternative method of charging energy for these devices. They only charge electricity when they are in the sun. If the sun is not shining so strongly or not at all (for example at night), there is no other way to charge the battery of a smartphone or tablet.

In contrast, solar chargers with a built-in battery solve this problem. The electricity that is generated from the sun's energy every time it shines can be stored in the battery and saved for later. At another time, you can then connect your smartphone and it will be charged. When the sun is shining, you can unpack the charger and start collecting power for bad times.

Solar chargers with rechargeable battery have a big advantage. You can use the charger during the day when the sun is shining and save power for the evening. Most of the time you charge your smartphone or tablet overnight, because you have used it all day. This is where the battery comes in and supplies the stored energy.

However, there is also an alternative possibility. For example, if you already have a normal power bank, you can combine it with a pure solar charger. This way you can plug the Powerbank into the solar charger during the day. This charges the solar energy and the Powerbank then functions as a battery. In the evening you can easily recharge your smartphone, camera or tablet using the energy stored in the Powerbank.

This procedure, the combination of pure solar charger and Powerbank, offers two advantages. This is because it can take a long time to recharge from solar energy using a pure solar charger. Sometimes such a charger needs up to 24 hours to be fully charged and to supply the electrical devices with power.

So it is better to store electricity whenever possible. It also allows you to charge your smartphone or tablet at night with solar energy and use your electrical devices during the day without any restrictions.

  • To extend the life of Powerbanks, extreme temperatures should be avoided.
  • Some Powerbanks can be charged while supplying power to another device.
  • Normally, the higher the capacity, the larger and heavier the Powerbank.
  • If two devices are charged at the same time, the charging time of both devices can be extended.
 

Test procedure

In the run-up to the test, we defined practical requirements and the following test criteria:

  • Usable capacity
  • Functional scope
  • Workmanship
  • Size to capacity

In order to evaluate these criteria, we have defined several tests for the Powerbanks. First, the scope of delivery and the connections are checked. A measuring device is used to check the actual usable capacity of the devices.

The Powerbanks are completely discharged and the time required for charging is then measured. During discharging and charging, the temperature development is also recorded with a thermal imaging camera.

Setup of the capacity measurement
Setup of the capacity measurement

As the test progresses, the devices are intentionally short-circuited and overloaded to test how the Powerbanks react in such a case and whether they are still functional afterwards.

Finally, a drop test is performed from a height of one meter to see if the devices are still working properly. If, according to the manufacturer, the devices are protected from water and dust, this is checked in separate procedures.

In order to exclude mistakes and to ensure the load by the everyday use, each test takes place in several rounds.

The test criteria are given percentages depending on their importance. The final score is then objectively calculated from the test criteria using an algorithm.

Product selection

Our product selection is based on observation of the current market. In addition to popular branded products, we also include insider tips in our selection. Criteria such as price and range of functions are an important factor to us. The test field is also determined by analysis and evaluation of customer reviews and external tests (e.g. Stiftung Warentest).

The devices are purchased anonymously or lent to us by the manufacturer. Dealers and manufacturers have no influence on the tests and our evaluation.

As soon as new relevant products come onto the market, our test field is extended by these. The new products go through the same test as the already tested devices.

The word "Powerbank" can be interpreted as "energy storage". "Energy storage" is a good description because this is exactly what a Powerbank does: store energy. And, of course, releasing it again. To our smartphone or other mobile devices, for example. A Powerbank is therefore a mobile charging station. So far, so good.

How is a Powerbank structured?
A Powerbank has a simple structure and usually consists of the following components:

  • Housing
  • Load input (Input)
  • USB ports for charging devices (output)
  • Control for charging and discharging the battery (which prevents short circuits and overcharging)
  • and of course a rechargeable battery (mostly in the form of lithium polymer or lithium ion batteries).

Most Powerbanks are used to charge smartphones, tablets and other small mobile devices. However, there are also larger Powerbanks that are capable of supplying power to a laptop, for example. And that is basically what a Powerbank is. Quite simple.

How Powerbanks work
You may be wondering how exactly a power bank stores the power that it later delivers. Put simply, it's like this:

Step 1: The Powerbank is connected to the socket via a charging cable.

Step 2: The power from the socket - electrical energy - is converted by the Powerbank to chemical energy, which the Powerbank can store in the built-in battery.

Step 3: This chemical energy can now be stored over a longer period of time - with losses occurring over time (usually between 2 and 20% within a few months). Cold and heat can also lead to loss of capacity, as you can read below.

Step 4: If necessary, compatible devices can now be charged via the Powerbank.

The capacity of Powerbanks - and batteries in general - is given in mAh. "mAh" stands for "milliampere-hours". Ampere is a unit for current and "milli" means "one thousandth" (one ampere is exactly 1000 milliamperes). "1000 milliampere hours" means that a battery can constantly deliver 1 milliampere per hour to a device to be charged for 1000 hours. Or 1000 milliamperes in one hour (i.e. 1 ampere per hour).

"Volt" is the unit in which the potential is indicated - i.e. the "pressure" with which the current flows through the conductor (e.g. a cable).

The power can be calculated by specifying amperes and volts. The unit for the electrical power is "Watt". In watt hours (Wh) or kilowatt hours (kWh) the electricity consumption is indicated. "Kilo" here means "thousand" - 2000 watt hours are thus 2 kilowatt hours. If a device - for example a microwave - has a power consumption of 2 kilowatt hours, this means that the device consumes 2 kilowatt of power per hour. The formula to calculate the power using voltage and current is as follows:
Power = Voltage * Current

Are you sitting in the office all day and just want to spend the last few hours of the day comfortably on the couch with your mobile phone and Powerbank? Instead of being near a power outlet in a crippled position?
Then, of course, you don't need the same Powerbank that an adventurer who wanders the wilderness for two weeks needs to power his cell phone and other important devices. Makes sense, doesn't it? Some possible uses are:

  • A small ultra-mobile power bank for everyday use with the smartphone to bridge the last few hours.
  • A medium-sized Powerbank for day trips or when several devices are charged with the Powerbank
  • A great power bank for travel and events
  • If you often work on your laptop on the go, special Powerbanks are available with an ordinary power outlet.

Here are a few more details for each scenario:

Ultra-mobile Powerbank for everyday use with the smartphone
As a rule, these Powerbanks only have a capacity of 2,000 to 4,000 mAh. With such Powerbanks, your smartphone can only be fully charged by approx. 30 to 70%.
However, this is more than enough, since our goal is only to use our mobile phone for a few more hours.

For example, if you're on your way home after work and notice that your smartphone is almost empty. Instead of looking bored out of the window, you unpack your little powerbank and watch some videos on your phone or check your messages.
For this scenario it is important that the Powerbank doesn't weigh too much. We don't want to feel like we're carrying a brick around all the time.

Often these Powerbanks are just a little bigger than a lipstick. So these Powerbanks are ideal to always have them with you in your trouser, jacket or handbag. The compact shape also makes it easy to charge your smartphone while it's in your pocket with the Powerbank. Very convenient, isn't it?

Another useful option are mobile phone cases with a built-in Powerbank. You don't have to worry about anything. The Powerbank merges with the mobile phone and you still only have one item in your pocket. The disadvantage is that the mobile phone becomes heavier. For many, however, this is no problem after a familiarization period.

Medium-sized power bank for day trips or to charge several devices
Are you often on the go for a whole day? Or do you want to charge more than one device during travels? In this case, a larger power bank is recommended. Our ultra-mobile Powerbank is no longer enough.

Ideally, the capacity is not too large and not too small. 5,000 to 10,000 mAh are perfect in most cases. For safety's sake, just calculate your needs. This only takes a few minutes and may save you a nasty awakening.

A great power bank for travel and events
If you regularly travel or attend events, you may need an even bigger Powerbank. Here Powerbanks with 10,000 to 40,000 mAh come in handy.

But attention: At latest 20'000 mAh become very heavy. To carry such Powerbanks around in your handbag - let alone in your trouser pocket - is not very comfortable. So plan to take a backpack with you.

Powerbanks for laptops and other devices
These Powerbanks usually start at 20'000 mAh. So they are already big. Since a backpack is necessary for the laptop anyway, this is not a big problem. Especially if we compare the advantages to this small disadvantage.

It should be noted here whether the Powerbank comes with a full power socket or only with adapters for the most common laptops. In the second case, we have to make sure that the adapter that fits our laptop is also included. Otherwise we can usually buy a suitable adapter. The advantage of a fully-fledged power socket is of course that you can also use other devices with this Powerbank. For example the fan at a picnic. Or a small mixer for the delicious smoothie on the way.

The required capacity of your Powerbank depends on which devices you want to charge and how often you want to charge them. With the following information you can estimate the ideal capacity for your Powerbank.

Battery capacities of popular smartphones

In addition, we look at the battery capacity of some popular smartphones (as of March, 2019). Our choice is the iPhone XS and some popular Android smartphones:

  • Apple iPhone XS - 2,716 mAh
  • Huawei Mate 20 - 4,000 mAh
  • Huawei Mate 20 Pro - 4,200 mAh
  • Samsung Galaxy S9 - 3,000 mAh
  • Samsung Galaxy S9 Plus - 3,500 mAh

As a rule of thumb, the capacity of batteries ranges from 3,000 to 4,000 mAh. With this information it is now easy for us to answer our original question:

How to calculate the ideal capacity for your needs

As mentioned above, the ideal capacity depends on your application. For example, if you want your Powerbank to be able to fully charge a 3,500 mAh smartphone, the Powerbank's capacity must be at least the same.

Typically, the higher the capacity, the bigger and heavier the Powerbank.

To be on the safe side, however, you should add another 40% to this value. Because if a Powerbank has a capacity of 3,500 mAh, then these 3,500 mAh are not completely available for charging devices. During charging, about 30 to 40% of the energy is lost.

For this reason, we add 40% to our 3,500 mAh and get 4,900 mAh. So your ideal power bank has a capacity of about 5,000 mAh.
In this way you can easily calculate the ideal capacity of your power bank.

The capacity of rechargeable batteries (and therefore of Powerbanks) decreases rapidly if used incorrectly. Here are some general tips to extend the life of your Powerbank:

Avoid extreme temperatures

Batteries lose capacity when exposed to extreme temperatures. So ideally don't leave your Powerbank on the dashboard under the windshield in the blazing sun in midsummer.

Extreme heat can destroy the interior of batteries. To be more precise, heat can cause some of the liquid in the batteries to evaporate. This causes the battery to lose capacity.

To extend the life of power banks, extreme temperatures should be avoided.

Low temperatures cause the Powerbank to discharge faster. So if you spend a lot of time outdoors in winter, your Powerbank will have a lower capacity than in spring, for example.

The ideal temperature for batteries is 5 to 25° Celsius. Avoid temperatures below -10 and above 40° Celsius. Ideally, keep your Powerbank in your pocket, handbag or backpack. It should neither be too hot in summer nor too cold in winter.

Avoid overheating when loading

In addition to overheating caused by an environment that is too hot, there is another cause for overheating batteries: overheating caused by charging the batteries.

Or more precisely, overheating because the power bank is not disconnected from the power supply when it is fully charged. This can cause the batteries to overheat. Therefore, it is recommended that Powerbanks and other devices with rechargeable batteries should not be supplied with electricity after they have been fully charged.

High-quality Powerbanks, however, usually have an overcharge protection built in that prevents the Powerbank from overcharging.

Avoid overheating during discharge

If your Powerbank overheats when charging from your smartphone (or other device), this may be because the Powerbank is not suitable for your smartphone. For example, because the charge current is too high.

In the worst case, overheating can cause the Powerbank to spontaneously ignite or explode. Therefore, make sure that the Powerbank and your mobile phone are compatible to each other.

Avoid deep discharge
What is a deep discharge? This means that the battery is completely discharged. The state of charge is 0%. Why is this bad? Depending on the type of battery, a single deep discharge can destroy the battery. In other cases the battery loses capacity.

High-quality Powerbanks usually have a deep discharge protection built in to prevent a deep discharge. To be on the safe side, your Powerbank will never discharge more than 80% (so that your Powerbank remains 20% charged).

Avoid shocks
Compared to smartphones and other devices, Powerbanks are very robust. Therefore, they are often treated rather carelessly by users. Shocks, however, can lead to dangerous defects and should therefore be avoided.

Ideally, you should keep your Powerbank in a protective case, which will protect your Powerbank in case it falls down, for example.

Special care should be taken if you notice an unusual change in temperature after your Powerbank has dropped. For example when loading or unloading the Powerbank. In this case it is advisable to dispose of the Powerbank.

Are there any safety risks associated with Powerbanks?
Usually, not really. However, since there is a lot at stake on a flight, even the smallest possible safety risks are taken extremely seriously. To be precise, a short circuit can occur in a Powerbank, causing the Powerbank to ignite itself (or even explode). This happens very, very rarely - but you can read about it in newspapers from time to time.

In any case, fire in an airplane can have fatal consequences. And that's why there are strict guidelines for Powerbanks and other battery-powered devices.

For example, batteries are not allowed in checked luggage. Why? Because there's nobody in your bag who will notice when your Powerbank suddenly starts to burn. You can usually carry Powerbanks and other battery-powered devices in your hand luggage.

However, there are guidelines here as well. The bigger the battery, the more likely it is that the battery will short-circuit and start to burn. For this reason, the International Air Transport Association (IATA) has set an upper limit for allowed batteries.

At the moment this is 100 watt hours. You can usually find the number of watt hours on the website of the manufacturer of your Powerbank. The problem is that not all airlines adhere to this policy. Many airlines have even stricter guidelines. So check with your airline about the exact policy, in order to be safe.

The selection of Powerbanks is large. The question is what to consider when making your selection. In this section you will find some tips for choosing the perfect Powerbank.

Capacity

First of all, you need to think about what capacity your Powerbank should have. The ideal capacity depends on your usage. For more information, see "Which powerbank suites me best?".

Form factor

The next criterion is the form factor.
Generally, flat Powerbanks are to be preferred before round Powerbanks. They fit into pockets more easily. This is especially important for small ultra-mobile Powerbanks.

A flat Powerbank can easily be placed together with the mobile phone in the trouser or jacket pocket and used at the same time. But even with larger Powerbanks, a flat design is often more practical and easier to accommodate.

Fast Charging / Quick Charging

If your smartphone supports Fast Charging or Quick Charging, then it makes sense to choose a Powerbank that supports this as well, so that your phone hangs on your Powerbank for as short a time as possible.

It's also handy if the Powerbank itself supports Fast Charging or Quick Charging and can be recharged quickly. It often makes sense to spend a little more to benefit from this useful feature.

Ports and Accessories

Also make sure your Powerbank comes with the right port and accessories. For example, if you want to charge more than one device at a time you should also buy a powerbank with the right number of ports.

Some Powerbanks can be charged while powering another device.

And the right kind of port. USB-C, micro USB, mini USB, etc. Or a Lightning port for the iPhone. You may have to buy a suitable adapter. A short USB cable is often useful for mobile use.

Another option is wireless charging. If your smartphone supports inductive charging, you could choose a powerbank that enables this. However, this is usually less convenient if you want to charge your phone on the go. This way of charging your phone is also relatively slow.

Charge Meter

An important function of every power bank is the charge level indicator. This is the display that shows you how full your Powerbank is. There are several options:

  • A single LED. Mainly used for small Powerbanks. Shows only if the Powerbank is full or almost empty.
  • Multiple LEDs. Indicates approximately how loaded the power bank is.
  • A small display with a percentage display

This feature is especially useful after the Powerbank has been unused for a long time. After a long time a Powerbank will discharge a bit (or more if the quality of the Powerbank is bad). The charge level indicator makes it easy to check if the Powerbank still has enough power. At least with the last two options.

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