How to choose a good USB data and charging cable for your mobile phone

Most of us will have a few USB data and charging cables for our mobile phone, i.e. one at home, one in office, one carrying together with our laptop, etc.

Do you encounter the problem of slow charging, or worst still, unable to charge with the additional USB cable that you bought? Perhaps you can find the solution after reading this.

First of all, although most of the USB cables look alike from their external appearance, they might be different inside the cable, and probably that is the ready why certain USB cable unable to charge your mobile phone, certain can charge but at a very slow rate, certain just work as fine as the original USB cable that come with your phone, and certain even can charge faster than the original cable.

There are 5 wires inside the USB 1 and USB 2 cables, and there are more inside USB 3.0 cable. Since most of the mobile phones nowadays are using USB 2.0 connector, so USB 3.0 is out of our topic here.

The 5 wires are:

• 2x 28 AWG data lines
• 2x 20-28 AWG power conductors
• 1x drain wire

and those 5 wires are connected to the 5 pins in your micro-USB connector.

In fact, there are two kinds of USB cable: fully-rated and sub-channel. The main difference between them is that fully-rated cable can be used for typical peripherals operating at the rate of 480 Mbps (high speed) signalling, while the sub-channel one at the rate of 1.5 Mbps (standard speed) signalling. The construction inside the cable fully-rated and sub-channel cable is different.

As you can see from the diagram above, the fully-rated USB cable is shielded by braid and aluminium foil.

You can probably see some printed codes on the good quality USB cable, including something like this: "28AWG/2C and 24AWG/2C" or "28AWG/1P + 24AWG/2C".

The first code is normally the specification of the data signal pair, which is normally 28AWG. "2C" means 2 conductors, and "1P" or "1Pr" means 1 pair. "2C" and "1P" are basically the same.

The important part is the second code, which is the specification of the power distribution pair. The minimum requirement is 28AWG, and the lower the AWG number the better. This is because lower AWG wire is thinker, and therefore the electrical resistant is lower.

Therefore, charging with a "28AWG/1P + 28AWG/2C" USB cable is normally slower than a "28AWG/1P + 24AWG/2C" cable.

Certain USB cable comes with a ferrite bead at one end, which function is to filter high frequency noise to improve signal transfer.

As a conclusion, when you buy additional USB cable to charge your mobile phone, you should look for:

• USB 2.0 support
• High speed 480 Mbps data transfer rate
• The packaging mentions it is a "charging" cable and not only a "data" cable
• Power conductors of 24AWG/2C or better (for faster charging speed)
• (optionally) the ferrite bead

Remember not to only look for the information on the packaging of the cable. Sometimes you will find the specification printed on the cable is different from that mentioned on the packaging.

Beware of dishonest cheap power bank claimed to have high mAh capacity

One of the key issue of mobile phones, particularly smartphones, is that they are power hungry causing their battery doesn't last long. As a result, mobile power bank comes into the market as portable external power source to supplement the internal battery of the mobile phone or mobile device.

While most of the modern mobile devices nowadays are using Li-Polymer battery (鋰聚合物電池) as their power source, a lot of mobile power banks are using the cylindrical or prismatic Li-Ion battery (鋰離子電池).

The major problem or hazard of Li-Ion battery and Li-Polymer battery is that, they will overheat when 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. If the IC is malfunctioned, the battery might caught fire or explode when overcharged. (Note: the original article mentioned Li-Polymer will not explode due to overcharge, which I think is not true.)

Another disadvantage of Li-Ion battery is their lifespan will greatly reduced if they are operating in high temperature of 45°C and above. Li-Polymer battery, on the other hand, has higher endurance to high temperature, and can still operate over 4 hours in 85°C without much problem.

Nowadays, you can find a lot of power banks claimed to have charge capacity as high as 12000mAh, 18000mAh, 20000mAh, or even higher, selling at the Internet stores. If they are unbranded and selling at a very cheap price, you need to be alerted before placing your order.

The shorter power bank in the picture above consists of 4 Li-Ion 18650 batteries, while the longer one consists of 6 Li-Ion 18650 batteries. The size of the cylindrical Li-Ion battery in used is 18.25x65mm, and their manufacturing part number is normally in the form of XXX18650-XX.

The quality of Li-Ion battery differs.

Branded made-in-Japan (eg. Sanyo, Panasonic) one normally has capacity of at least 3100mAh, and comes with 1 year warranty. They have higher price too and won't be chosen to make the cheap power bank selling in the Internet stores.

Branded made-in-Korea (eg. Samsung) one is quite reliable too. Part number could be ICR18650-30A, ICR18650-28A, ICR18650-26F, ICR18650-26D, ICR18650-24E, ICR18650-24F, ICE18650-22F, etc. 30F means capacity is 3000mAh, 22F means capacity is 2200mAh, and so on.

Samsung OEM made-in-China Li-Ion battery has 4 grades. The highest A01 grade normally reserved for Samsung own use, while A02, A03 and A04 are made available for customers. Part number could be ICR18650-20, ICR18650-22, ICR18650-24, ICR18650-26, etc. If a power bank claimed to use Samsung batteries, the batteries inside are probably the A02~A04 type.

Certain unbranded made-in-china battery were found to have only 1600-1800mAh but also put in the 18650 code and claimed to have 3000mAh. The cheap power banks probably are using this kind of Li-Ion battery.

For the power bank with 12000mAh capacity above, its capacity is calculated like this:

3000mAh x 4 = 12000mAh

However, if the real capacity of the batteries inside is only 2200mAh, you can only get 2200mAh x 4 = 8800mAh.

For the power bank with 18000mAh capacity above, its capacity is calculated like this:

3000mAh x 6 = 18000mAh

However, if the real capacity of the batteries inside is only 2200mAh, you can only get 2200mAh x 6 = 13200mAh.

Beside the possible short-change in real capacity, since the size of the Li-Ion batteries are the same, some dishonest power bank might even use recycled batteries!

 

The picture above is said to be taken from a newly purchased cheap power bank, opened up for inspection. Note that the colour of the 6 Li-Ion batteries are all different, which is very unlikely if they are manufactured from the same batch.

 



Also note that the soldering point is rusted and shows sign of multiple re-soldering. There is also leftover glue on the surface.

Worse still, what if the cheap dishonest power bank does not have a properly functioning overcharge / over-discharge circuit?

And even more ridiculous case, you probably get only a single Li-Ion battery with 2 bags of sand.

So, better be cautious when you buy power bank either from Internet or shop, especially when the product is unbranded and the price is cheap.

Note: The above article is excerpted and translated from its original source posted in Chinese by a Taiwanese called 曾家辉 in his Facebook page. The photos above are taken from his original article.

Malaysia Interbank GIRO money transfer cost to reduce to 10 sen, cheque will be charged processing fee on top of stamp duty

Bank Negara Malaysia (BNM) plans to encourage paperless electronic money transfer by greatly reduce the charge of Interbank GIRO (IBG) money transfer with Internet banking or mobile banking, and at the same time greatly increase the cost of cheque transaction by charging processing fee on top of the existing stamp duty of each cheque issued out by the consumer.

Effective 2 May 2013, bank charge for IBG transaction performed online via internet banking or mobile banking will be reduced to RM0.10 only, compared to the current rate of between RM1-RM4.

On the other hand, from April 2014 onwards, the a processing fee of RM0.50 per cheque transaction will be charged, on top of the existing RM0.15 stamp duty, making the transaction per cheque to cost RM0.65. The processing fee will gradually increase to the level of RM3 in the future.

Note that before 2010, outstation cheques were charged RM0.50 by the bank for clearing. That charge was waived since the implementation of Cheque Truncation and Cheque Conversion System (CTCS) in Malaysia. Now it seems that the RM0.50 cost will be added back in the form of processing fee, and this time, is regardless the cheque is local or outstation.

It is a good news for online banking users to be able to transfer money electronically at a much lower cost in the near future.

However, as far as we know, transferring of money via online banking is capped to RM5,000 per day or so. Unless the banks revise this limit, it will bring inconvenient to us. In certain occasions, writing cheque is still the more preferred way, especially when the amount of money is large, such as buying a car, buying a house, paying lawyer fee, etc.

It is also a more common practice for companies to make payment in cheques.

I hope that BNM will really think through carefully before enforcing the "discouraging mechanism" of using cheque in order to get people to use electronic money transfer.