The mAh competition
Power banks, or mobile battery packs / chargers, as they are alternatively known are popular with the mobile crowd. Given our obsession with facebook and youtube on the go, energy hungry tablets and mobiles drain out their batteries quickly. For busy executives on the go, the biggest nightmare would be that it's not even midday and you have a flat battery. In such situations, powerbanks can be a real life saver. They have also increasingly been popular as a gifts for children going to college or as a corporate gift.
There has been a flood of new entrants into an already crowded market given popularity of the devices. Powerbanks have increasingly been marketed with ever higher capacities, or mAh. 5600mAh, 1200mAh, to even an incredible 50000mAh! Meanwhile, crazily low prices have been bandied around to entice consumers.
Logically, it would feel like something is wrong. So where is the catch?
Given that the iPAD has battery capacity of 11666mAh and the Samsung Galaxy S4 has a capacity of 2600mAh, it confounds me why do we even need such high capacity powerbanks.
One of the most common, and hard to detect, practice among unscrupulous manufacturers is to falsify the declared capacity of the cell.
I've met this Chinese manufacturer at a China trade fair peddling power banks for an incredible price. Curious, I questioned the sales person in greater detail about the product. With some probing, I realized that the reason why the price was so cheap was because they were cutting corners on the product. I was shocked that they openly admitted that the industry standard was to use a 1800mAh cell into the product and pass it off as 2400mAh cell. Upon a closer comparison with a host of other manufacturers at the same fair, it seemed to confirm my suspicious. Each of them carried a similar design of the product, however, the capacities ranged from 2200, 2400, 2600 and 2800 to even 3200mAh.
Even more suspicious were products being marketed as 6000mAh or higher but seemed impossibly light to carry. I cringe each time i come across online buyers who commented that their 30000mAh powerbank was great because it was so light. In reality, the only reason why a powerbank is light is because the manufacturer cheated on the number of cells within.
Larger capacities are achieved by lining up various cells (generally Li-polymer or Li-ion 18650 cells) in a series. Inside that pretty casing, powerbanks function pretty much like the AA batteries that we are familiar with. Therefore, the only reason why your so-called 30000mAh is so light is because it's probably missing a fair number of cells.
Even if it feels that the weight is right, it still may not be. One famous photo (from lowyat.net) circulating around the net proves the point succinctly. A nice case advertised for some huge capacity at an impossibly attractive price. Open it up and you get 1 cell, and a lot of sand.
As the capacity of the battery is hard to test, most resellers and retailers don't know any better.
2800mAh, 2600mAh, 1800mAh, so which is the real product?
Naturally there are many grades of batteries being produced, similar to any product such as fruit or airline seats. There are the grade A all the way to the rejects. The best quality cells almost never get onto the market to 3rd party manufacturers. Large factories producing for Sony or Samsung for example would naturally draw upon the best Grade A batteries for their own product labels. These cells are excellent and normally come with 1 year warranty. The next tier would be for the mid range labels and so on and so forth.
Hence, that brandless cheap powerbank probably is using a poor grade cell. No only does it hold charge poorly, there is also poor charge transmission. So that 30000mAh battery pack that you bought may not even manage a 5000mAh charge in reality!
In addition, the risk is of batteries that are not of the same batch. We know that battery makers always advise against mixing different brands of batteries, or even different batches of batteries. The same theory holds here for power banks. Mixing different batches causes unstable current or may result in charging / discharging issues that may damage your electronics!
Cells from a different batch
While most of the modern mobile devices nowadays are using Li-Polymer battery as their power source, most of the cheap products on the market are using the cylindrical or prismatic Li-Ion battery.
The major problem or hazard of Li-Ion batteries and Li-Polymer battery is that, they will overheat when it is charged for long time. There is an overcharge prevention IC on its circuit board to cut off the charging when the battery is fully charged. However, in a poorly manufactured cell, if the IC is faulty, the battery might caught fire or explode when overcharged. This is a real risk as most users tend to charge their powerbanks at night while they are sleeping. Similar to power banks, there have been occurrences of cell phone batteries made in China exploding. A quick check on the net would bring up incidents of people being killed due to battery explosions. In a recent case 2013, a Samsung S4 Galaxy battery caught fire and burnt down an apartment in China.
All this is due to the overheating of batteries and faulty IC on the product. With cheap manufacturers, the last thing on their minds is your safety.
What can you do?
So what can you as consumers do?
It's notoriously hard to test for the reliability of a powerbank.
Some points, well which are really common sense.
- Be suspicious of powerbanks that sound too cheap to be true. Often it always is.
- Go for products from well known brands. Generally they would have a higher level of quality control as they are concerned about their brand image and reputation.
- Do your research. Read customers' reviews.
- Do not leave your powerbank to charge overnight.
- Choose Li-polymer cells over Li-ion where possible.
- Choose a smaller capacity if possible so that the risk of fire / fault is lower. You only need the powerbank to get you to a power main don't you? So why do you need a 50000mAh product to last you 5 charges?
- Six Terrible Corporate Gifts
What better way to destroy your standing with your customers than to present them with awful corporate gifts. You might as well not give them anything!
James on November 18, 2016:
While this article is largely accurate in it's assessment of the situation, some key details simply wrong.
The article mentions that the cells are placed in "series", however this is not the case, they are actually in "parallel". It also states that manufacturers mix cells of different batches or brands and this could cause "unstable current" or damage electronics. This is not the case! While it may still be indicative of a poor quality process, or the use of reclaimed cells... the actual act of placing different types of 18650 cells in "parallel" does not in itself cause any issues (manufacturers warnings against mixing cells of different types apply to cells in "series", not "parallel"... and regular alkaline or NiMh / NiCd cells cannot be used in parallel like LiIon/LiPo cells can).
Also, cells used in this type of electronics are "unprotected", (do not contain a protection IC), because the charge circuit on the PCB is supposed to manage the charge voltage.... overcharging is possible, but most failures are caused by faulty or damaged cells shorting out internally.