When shopping for power banks in South Africa, you should be wary of fake products which have far less capacity than they claim on their packaging.
There are a number of suspicious power banks listed for sale in South Africa, usually boasting very high capacities and surprisingly cheap price tags.
To determine whether these products are legitimate, we purchased a number of power banks with the objective of taking them apart and determining their real capacities.
Abu-Huraira Abdalla, director of Mañana Technologies, contacted MyBroadband about this issue and worked with us to test the power banks and identify the actual lithium-ion cells in the products.
Mañana Technologies is an ICT consulting company which provides expert technical advisory to prominent companies in South Africa.
Before we get into the results of the battery test, it is important to understand how battery capacity is measured, and why milliamp-hours (mAh) is not necessarily an accurate reflection of capacity.
Why mAh can be misleading
In Europe, the United States, and many other countries, power bank manufacturers are required to print the device’s capacity in watt-hours (Wh) on their packaging in addition to mAh.
Laptops also comply with this standard, listing Wh when stating battery capacity and never just mAh alone.
This is because the mAh measurement is dependent on the voltage of the power draw, while the Wh reading is an accurate measurement of capacity at any voltage.
For example, when capacity is stated in mAh on power banks and other devices, the standard used is usually 3.7V. This means that a 10,000mAh power bank will be able to provide 1A (1,000mAh) over a period of 10 hours at 3.7V.
However, at higher voltages, this “capacity” measurement would decrease. At 5V, the same power bank would only provide 7,400mAh.
The accurate capacity measurement for this power bank would be 37Wh, as this number reflected the actual energy capacity of the cell, instead of the time it can supply current at a certain voltage.
Watt-hours (Wh) is equal to amp-hours (Ah) multiplied by voltage (V). Using this formula, the Wh capacity of the 10,000mAh power bank mentioned earlier is 37Wh.
This figure will not change, no matter the voltage at which the mAh is calculated, as it reflects the number of hours the power bank can provide 1W of energy.
In other important energy measurements, such as the calculation of your electricity bill, Wh is used as an accurate measurement.
Power banks in South Africa and a number of other countries prefer to use mAh, however, operating under the assumption of compliance to an industry standard of 3.7V for calculating capacity, as this is the de-facto voltage standard for most mobile phones and tablets.
To determine the real capacity of several suspicious power banks, we ordered a number of products through local online retailers which seemed especially cheap considering their capacities.
We disassembled the battery banks and inspected the cells to determine their real capacities.
The capacity of each cell in the power bank was then added together to calculate the real total capacity of the power bank, which we measured in Wh and in mAh at 3.7V.
During these tests, we encountered unlabelled 18650 lithium-ion cells which weighed much less than a 2,000mAh (7.4Wh) labelled cell (37g vs 43g).
We ran depletion tests on these cells and found them to last only around a third of the time as the 2,000mAh cell at the same voltage drain, and we generously estimated their capacity to be a maximum of 1,000mAh.
This estimate was reached following the conduction of depletion tests and the consultation of weight discrepancies in fake cells recorded by many other battery tests.
Below are the results for the power banks we tested.
|Brand||Stated Capacity||Cells||Real Capacity|
|Energizer||5,000mAh||2 x 18650 2,500mAh||5,000mAh|
|Fonsi||10,000mAh||1x 606090 4,000mAh||4,000mAh|
|Fonsi||30,000mAh||8x 18650 2,000mAh||16,000mAh|
|Viaking||12,800mAh||5x 18650 1,000mAh*||5,000mAh|
|Sinye Tech||26,800mAh||8x 18650 1,000mAh*||8,000mAh|
As can be seen from the tests above, there are a number of cheaper power banks for sale in South Africa which are dishonest about their capacity.
Whether they have calculated their mAh using a voltage which is lower than the 3.7V or have simply misstated the capacity, it is important to beware of equating these power banks with those labelled correctly.
Judging from our tests above, you should avoid “no name-brand” devices which are significantly cheaper than the competition, as well as cheaper power banks from Fonsi, Viaking, and Sinye Tech. If it seems too cheap to be true, it usually is.
It is important to note that the branded power banks which were found to have incorrect capacities were not listed under their brand names at retailers – the brand names only appeared on their packaging once they were shipped.
MyBroadband reached out to OneDayOnly and various other retailers who sell or have previously sold these power banks in an effort to contact the suppliers of the products.
Unfortunately, none of the retailers we contacted who stocked these devices were able to provide their suppliers’ names or contact details.
“Unfortunately, our policy is not to divulge who our suppliers are,” OneDayOnly said.
Below are images of the lithium-ion cells encountered during the disassembly of the power banks.